1.0.1.RELEASE-hadoop21
Table of Contents
- Preface
- I. Introduction
- II. Spring and Hadoop
- 3. Hadoop Configuration, MapReduce, and Distributed Cache
- 4. Working with the Hadoop File System
- 5. Working with HBase
- 6. Hive integration
- 7. Pig support
- 8. Cascading integration
- 9. Using the runner classes
- 10. Security Support
- III. Developing Spring for Apache Hadoop Applications
- IV. Spring for Apache Hadoop sample applications
- V. Other Resources
- VI. Appendices
Spring for Apache Hadoop provides extensions to Spring, Spring Batch, and Spring Integration to build manageable and robust pipeline solutions around Hadoop.
Spring for Apache Hadoop supports reading from and writing to HDFS, running various types of Hadoop jobs (Java MapReduce, Streaming), scripting and HBase, Hive and Pig interactions. An important goal is to provide excellent support for non-Java based developers to be productive using Spring for Apache Hadoop and not have to write any Java code to use the core feature set.
Spring for Apache Hadoop also applies the familiar Spring programming model to Java MapReduce jobs by providing support for dependency injection of simple jobs as well as a POJO based MapReduce programming model that decouples your MapReduce classes from Hadoop specific details such as base classes and data types.
This document assumes the reader already has a basic familiarity with the Spring Framework and Hadoop concepts and APIs.
While every effort has been made to ensure that this documentation is comprehensive and there are no errors, nevertheless some topics might require more explanation and some typos might have crept in. If you do spot any mistakes or even more serious errors and you can spare a few cycles during lunch, please do bring the error to the attention of the Spring for Apache Hadoop team by raising an issue. Thank you.
Spring for Apache Hadoop provides integration with the Spring Framework to create and run Hadoop MapReduce, Hive, and Pig jobs as well as work with HDFS and HBase. If you have simple needs to work with Hadoop, including basic scheduling, you can add the Spring for Apache Hadoop namespace to your Spring based project and get going quickly using Hadoop. As the complexity of your Hadoop application increases, you may want to use Spring Batch and Spring Integration to regain on the complexity of developing a large Hadoop application.
This document is the reference guide for Spring for Apache Hadoop project (SHDP). It explains the relationship between the Spring framework and Hadoop as well as related projects such as Spring Batch and Spring Integration. The first part describes the integration with the Spring framework to define the base concepts and semantics of the integration and how they can be used effectively. The second part describes how you can build upon these base concepts and create workflow based solutions provided by the integration with Spring Batch.
Spring for Apache Hadoop requires JDK level 6.0 (just like Hadoop) and above, Spring Framework 3.0 (3.2 recommended) and above and is built against Apache Hadoop 1.2.1. SHDP supports and is tested daily against Apache Hadoop 1.2.1 and also against 1.0.4 and 1.1.2 as well as against various Hadoop distributions:
-
Cloudera CDH3 (cdh3u5), CDH4 (cdh4.1.3 MRv1) distributions
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Hortonworks Data Platform 1.3
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Greenplum HD (1.2)
Any distro compatible with Apache Hadoop 1.x should be supported.
We have recently added support to allow 2.0.x based distributions to be used with the current functionality. We are running test builds against Apache Hadoop 2.0.5-alpha, Pivotal HD 1.0 and Hortonworks Data Platform 2.0.
![[Note]](images/note.png) | Note |
|---|---|
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Hadoop YARN support is only available in Spring for Apache Hadoop version 2.0 and later. |
Spring Data Hadoop is provided out of the box and it is certified to work on Greenplum and Pivotal HD distributions.
Instructions for setting up project builds using various supported distributions are provided on the Spring for Apache Hadoop wiki -http://cascading.org/http://hbase.apache.org/http://hive.apache.org/ https://github.com/SpringSource/spring-hadoop/wiki
Regarding Hadoop-related projects, SDHP supports Cascading 2.1, HBase 0.90.x, Hive 0.8.x and Pig 0.9.x and above. As a rule of thumb, when using Hadoop-related projects, such as Hive or Pig, use the required Hadoop version as a basis for discovering the supported versions.
Spring for Apache Hadoop also requires a Hadoop installation up and running. If you don't already have a Hadoop cluster up and running in your environment, a good first step is to create a single-node cluster. To install Hadoop 1.2.1, the "Getting Started" page from the official Apache documentation is a good general guide. If you are running on Ubuntu, the tutorial from Michael G. Noll, "Running Hadoop On Ubuntu Linux (Single-Node Cluster)" provides more details. It is also convenient to download a Virtual Machine where Hadoop is setup and ready to go. Cloudera, Hortonworks and Pivotal all provide virtual machines and provide VM downloads on their product pages. Additionally, the appendix provides information on how to use Spring for Apache Hadoop and setup Hadoop with cloud providers, such as Amazon Web Services.
While this documentation acts as a reference for Spring for Hadoop project, there are number of resources that, while optional, complement this document by providing additional background and code samples for the reader to try and experiment with:
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Spring for Apache Hadoop samples https://github.com/SpringSource/spring-hadoop-samples/. Official repository full of SHDP samples demonstrating the various project features.
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Spring Data Book http://shop.oreilly.com/product/0636920024767.do. Guide to Spring Data projects, written by the committers behind them. Covers Spring Data Hadoop stand-alone but in tandem with its siblings projects. All author royalties from book sales are donated to Creative Commons organization.
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Spring Data Book Hadoop examples https://github.com/SpringSource/spring-data-book/tree/master/hadoop. Complete running samples for the Spring Data book. Note that some of them are available inside Spring for Apache Hadoop samples as well.
This part of the reference documentation explains the core functionality that Spring for Apache Hadoop (SHDP) provides to any Spring based application.
Chapter 3, Hadoop Configuration, MapReduce, and Distributed Cache describes the Spring support for bootstrapping, initializing and working with core Hadoop.
Chapter 4, Working with the Hadoop File System describes the Spring support for interacting with the Hadoop file system.
Chapter 5, Working with HBase describes the Spring support for HBase.
Chapter 6, Hive integration describes the Hive integration in SHDP.
Chapter 7, Pig support describes the Pig support in Spring for Apache Hadoop.
Chapter 8, Cascading integration describes the Cascading integration in Spring for Apache Hadoop.
Chapter 10, Security Support describes how to configure and interact with Hadoop in a secure environment.
One of the common tasks when using Hadoop is interacting with its runtime - whether it is a local setup or a remote cluster, one needs to properly configure and bootstrap Hadoop in order to submit the required jobs. This chapter will focus on how Spring for Apache Hadoop (SHDP) leverages Spring's lightweight IoC container to simplify the interaction with Hadoop and make deployment, testing and provisioning easier and more manageable.
To simplify configuration, SHDP provides a dedicated namespace for
most of its components. However, one can opt to configure the beans
directly through the usual <bean> definition. For
more information about XML Schema-based configuration in Spring, see
this
appendix in the Spring Framework reference documentation.
To use the SHDP namespace, one just needs to import it inside the configuration:
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:hdp="
http://www.springframework.org/schema/hadoop" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/hadoop http://www.springframework.org/schema/hadoop/spring-hadoop.xsd
"> <bean id ... >
<hdp:configuration ...> </beans>
|
Spring for Apache Hadoop namespace prefix. Any name can do but
throughout the reference documentation, |
|
The namespace URI. |
|
The namespace URI location. Note that even though the location points to an external address (which exists and is valid), Spring will resolve the schema locally as it is included in the Spring for Apache Hadoop library. |
|
Declaration example for the Hadoop namespace. Notice the prefix usage. |
Once imported, the namespace elements can be declared simply by
using the aforementioned prefix. Note that is possible to change the
default namespace, for example from <beans> to
<hdp>. This is useful for configuration composed
mainly of Hadoop components as it avoids declaring the prefix. To achieve
this, simply swap the namespace prefix declarations above:
<?xml version="1.0" encoding="UTF-8"?> <beans:beans xmlns="http://www.springframework.org/schema/hadoop"
|
The default namespace declaration for this XML file points to the Spring for Apache Hadoop namespace. |
|
The beans namespace prefix declaration. |
|
Bean declaration using the |
|
Bean declaration using the |
For the remainder of this doc, to improve readability, the XML
examples may simply refer to the <hdp> namespace
without the namespace declaration, where possible.
In order to use Hadoop, one needs to first configure it namely by
creating a Configuration object. The configuration
holds information about the job tracker, the input, output format and the
various other parameters of the map reduce job.
In its simplest form, the configuration definition is a one liner:
<hdp:configuration />
The declaration above defines a Configuration
bean (to be precise a factory bean of type
ConfigurationFactoryBean) named, by default,
hadoopConfiguration. The default name is used, by
conventions, by the other elements that require a configuration - this
leads to simple and very concise configurations as the main components can
automatically wire themselves up without requiring any specific
configuration.
For scenarios where the defaults need to be tweaked, one can pass in additional configuration files:
<hdp:configuration resources="classpath:/custom-site.xml, classpath:/hq-site.xml">
In this example, two additional Hadoop configuration resources are added to the configuration.
| Note |
|---|---|
|
Note that the configuration makes use of Spring's
|
In addition to referencing configuration resources, one can tweak
Hadoop settings directly through Java Properties.
This can be quite handy when just a few options need to be changed:
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:hdp="http://www.springframework.org/schema/hadoop" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/hadoop http://www.springframework.org/schema/hadoop/spring-hadoop.xsd"> <hdp:configuration> fs.default.name=hdfs://localhost:9000 hadoop.tmp.dir=/tmp/hadoop electric=sea </hdp:configuration> </beans>
One can further customize the settings by avoiding the so called hard-coded values by externalizing them so they can be replaced at runtime, based on the existing environment without touching the configuration:
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:hdp="http://www.springframework.org/schema/hadoop" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/hadoop http://www.springframework.org/schema/hadoop/spring-hadoop.xsd"> <hdp:configuration> fs.default.name=${hd.fs} hadoop.tmp.dir=file://${java.io.tmpdir} hangar=${number:18} </hdp:configuration> <context:property-placeholder location="classpath:hadoop.properties" /> </beans>
Through Spring's property placeholder support,
SpEL
and the environment
abstraction (available in Spring 3.1). one can externalize
environment specific properties from the main code base easing the
deployment across multiple machines. In the example above, the default
file system is replaced based on the properties available in
hadoop.properties while the temp dir is determined
dynamically through SpEL. Both approaches offer a lot
of flexbility in adapting to the running environment - in fact we use this
approach extensivly in the Spring for Apache Hadoop test suite to cope
with the differences between the different development boxes and the CI
server.
Additionally, external
Properties files can be loaded,
Properties beans (typically declared through Spring's
util
namespace). Along with the nested properties declaration,
this allows customized configurations to be easily declared:
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:hdp="http://www.springframework.org/schema/hadoop" xmlns:context="http://www.springframework.org/schema/context" xmlns:util="http://www.springframework.org/schema/util" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util.xsd http://www.springframework.org/schema/hadoop http://www.springframework.org/schema/hadoop/spring-hadoop.xsd"> <!-- merge the local properties, the props bean and the two properties files --> <hdp:configuration properties-ref="props" properties-location="cfg-1.properties, cfg-2.properties"> star=chasing captain=eo </hdp:configuration> <util:properties id="props" location="props.properties"/> </beans>
When merging several properties, ones defined locally win. In the
example above the configuration properties are the primary source,
followed by the props bean followed by the external
properties file based on their defined order. While it's not typical for a
configuration to refer to so many properties, the example showcases the
various options available.
| Note |
|---|---|
For more properties utilities, including
using the System as a source or fallback, or control over the merging
order, consider using Spring's
PropertiesFactoryBean
(which is what Spring for Apache Hadoop and
util:properties use underneath). |
It is possible to create
configurations based on existing ones - this allows one to create
dedicated configurations, slightly different from the main ones, usable
for certain jobs (such as streaming - more on that below). Simply use the
configuration-ref attribute to refer to the
parent configuration - all its properties will be
inherited and overridden as specified by the child:
<!-- default name is 'hadoopConfiguration' --> <hdp:configuration> fs.default.name=${hd.fs} hadoop.tmp.dir=file://${java.io.tmpdir} </hdp:configuration> <hdp:configuration id="custom" configuration-ref="hadoopConfiguration"> fs.default.name=${custom.hd.fs} </hdp:configuration> ...
Make sure though that you specify a different name since otherwise, because both definitions will have the same name, the Spring container will interpret this as being the same definition (and will usually consider the last one found).
Another option worth mentioning is
register-url-handler which, as the name implies,
automatically registers an URL handler in the running VM. This allows urls
referrencing hdfs resource (by using the
hdfs prefix) to be properly resolved - if the handler
is not registered, such an URL will throw an exception since the VM does
not know what hdfs means.
| Note |
|---|---|
|
Since only one URL handler can be registered per VM, at most once,
this option is turned off by default. Due to the reasons mentioned
before, once enabled if it fails, it will log the error but will not
throw an exception. If your |
Last but not least a reminder that one can mix and match all these options to her preference. In general, consider externalizing Hadoop configuration since it allows easier updates without interfering with the application configuration. When dealing with multiple, similar configurations use configuration composition as it tends to keep the definitions concise, in sync and easy to update.
Once the Hadoop configuration is taken care of, one needs to actually submit some work to it. SHDP makes it easy to configure and run Hadoop jobs whether they are vanilla map-reduce type or streaming. Let us start with an example:
<hdp:job id="mr-job" input-path="/input/" output-path="/ouput/" mapper="org.apache.hadoop.examples.WordCount.TokenizerMapper" reducer="org.apache.hadoop.examples.WordCount.IntSumReducer"/>
The declaration above creates a typical Hadoop
Job: specifies its input and output, the mapper and the
reducer classes. Notice that there is no reference to the Hadoop
configuration above - that's because, if not specified, the default naming
convention (hadoopConfiguration) will be used instead.
Neither is there to the key or value types - these two are automatically
determined through a best-effort attempt by analyzing the class
information of the mapper and the reducer. Of course, these settings can
be overridden: the former through the configuration-ref
element, the latter through key and
value attributes. There are plenty of options available
not shown in the example (for simplicity) such as the jar (specified
directly or by class), sort or group comparator, the combiner, the
partitioner, the codecs to use or the input/output format just to name a
few - they are supported, just take a look at the SHDP schema (Appendix C, Spring for Apache Hadoop Schema) or simply trigger auto-completion (usually
CTRL+SPACE) in your IDE; if it supports XML namespaces
and is properly configured it will display the available elements.
Additionally one can extend the default Hadoop configuration object and
add any special properties not available in the namespace or its backing
bean (JobFactoryBean).
It is worth pointing out that per-job specific configurations are supported by specifying the custom properties directly or referring to them (more information on the pattern is available here):
<hdp:job id="mr-job" input-path="/input/" output-path="/ouput/" mapper="mapper class" reducer="reducer class" jar-by-class="class used for jar detection" properties-location="classpath:special-job.properties"> electric=sea </hdp:job>
<hdp:job> provides additional properties,
such as the generic options,
however one that is worth mentioning is jar which
allows a job (and its dependencies) to be loaded entirely from a specified
jar. This is useful for isolating jobs and avoiding classpath and
versioning collisions. Note that provisioning of the jar into the cluster
still depends on the target environment - see the aforementioned section for more info (such as
libs).
Hadoop Streaming
job (or in short streaming), is a popular feature of Hadoop as it allows
the creation of Map/Reduce jobs with any executable or script (the
equivalent of using the previous counting words example is to use
cat
and
wc
commands). While it is rather easy to start up streaming from
the command line, doing so programatically, such as from a Java
environment, can be challenging due to the various number of parameters
(and their ordering) that need to be parsed. SHDP simplifies such a task
- it's as easy and straightforward as declaring a job
from the previous section; in fact most of the attributes will be the
same:
<hdp:streaming id="streaming" input-path="/input/" output-path="/ouput/" mapper="${path.cat}" reducer="${path.wc}"/>
Existing users might be wondering how they can pass the command
line arguments (such as -D or
-cmdenv). While the former customize the Hadoop
configuration (which has been convered in the previous section), the latter are supported
through the cmd-env element:
<hdp:streaming id="streaming-env" input-path="/input/" output-path="/ouput/" mapper="${path.cat}" reducer="${path.wc}"> <hdp:cmd-env> EXAMPLE_DIR=/home/example/dictionaries/ ... </hdp:cmd-env> </hdp:streaming>
Just like job, streaming
supports the generic
options; follow the link for more information.
The jobs, after being created and configured, need to be submitted
for execution to a Hadoop cluster. For non-trivial cases, a coordinating,
workflow solution such as Spring Batch is recommended . However for basic
job submission SHDP provides the job-runner element
(backed by JobRunner class) which submits several
jobs sequentially (and waits by default for their completion):
<hdp:job-runner id="myjob-runner" pre-action="cleanup-script" post-action="export-results" job-ref="myjob" run-at-startup="true"/> <hdp:job id="myjob" input-path="/input/" output-path="/output/" mapper="org.apache.hadoop.examples.WordCount.TokenizerMapper" reducer="org.apache.hadoop.examples.WordCount.IntSumReducer" />
Multiple jobs can be specified and even nested if they are not used outside the runner:
<hdp:job-runner id="myjobs-runner" pre-action="cleanup-script" job-ref="myjob1, myjob2" run-at-startup="true"/> <hdp:job id="myjob1" ... /> <hdp:streaming id="myjob2" ... />
One or multiple Map-Reduce jobs can be specified through the
job attribute in the order of the execution. The runner
will trigger the execution during the application start-up (notice the
run-at-startup flag which is by default
false). Do note that the runner will not run unless
triggered manually or if run-at-startup is set to
true. Additionally the runner (as in fact do all runners in SHDP) allows one or multiple
pre and post actions to be specified
to be executed before and after each run. Typically other runners (such as
other jobs or scripts) can be specified but any JDK
Callable can be passed in. For more information on
runners, see the dedicated chapter.
| Note |
|---|---|
As the Hadoop job submission and execution (when
wait-for-completion is true) is
blocking, JobRunner uses a JDK
Executor to start (or stop) a job. The default
implementation, SyncTaskExecutor uses the calling
thread to execute the job, mimicking the hadoop command line behaviour.
However, as the hadoop jobs are time-consuming, in some cases this can
lead to “application freeze”, preventing normal operations or
even application shutdown from occuring properly. Before going into
production, it is recommended to double-check whether this strategy is
suitable or whether a throttled or pooled implementation is better. One
can customize the behaviour through the executor-ref
parameter. |
The job runner also allows running jobs to be cancelled (or killed)
at shutdown. This applies only to jobs that the runner waits for
(wait-for-completion is true) using
a different executor then the default - that is, using a different thread
then the calling one (since otherwise the calling thread has to wait for
the job to finish first before executing the next task). To customize this
behaviour, one should set the kill-job-at-shutdown
attribute to false and/or change the
executor-ref implementation.
For Spring Batch environments, SHDP provides a dedicated tasklet to execute Hadoop jobs as a step in a Spring Batch workflow. An example declaration is shown below:
<hdp:job-tasklet id="hadoop-tasklet" job-ref="mr-job" wait-for-completion="true" />
The tasklet above references a Hadoop job definition named
"mr-job". By default, wait-for-completion is true so
that the tasklet will wait for the job to complete when it executes.
Setting wait-for-completion to
false will submit the job to the Hadoop cluster but
not wait for it to complete.
It is common for Hadoop utilities and libraries to be started from
the command-line (ex: hadoop jar
some.jar). SHDP offers generic support for such cases
provided that the packages in question are built on top of Hadoop standard
infrastructure, namely Tool and
ToolRunner classes. As opposed to the command-line
usage, Tool instances benefit from Spring's
IoC features; they can be parameterized, created and destroyed on demand
and have their properties (such as the Hadoop configuration)
injected.
Consider the typical jar example - invoking a
class with some (two in this case) arguments (notice that the Hadoop
configuration properties are passed as well):
bin/hadoop jar -conf hadoop-site.xml -jt darwin:50020 -Dproperty=value someJar.jar org.foo.SomeTool data/in.txt data/out.txt
Since SHDP has first-class support for configuring Hadoop, the so called
generic options aren't needed any more, even more so
since typically there is only one Hadoop configuration per application.
Through tool-runner element (and its backing
ToolRunner class) one typically just needs to specify
the Tool implementation and its arguments:
<hdp:tool-runner id="someTool" tool-class="org.foo.SomeTool" run-at-startup="true"> <hdp:arg value="data/in.txt"/> <hdp:arg value="data/out.txt"/> property=value </hdp:tool-runner>
Additionally the runner (just like the job runner) allows one or
multiple pre and post actions to be
specified to be executed before and after each run. Typically other
runners (such as other jobs or scripts) can be specified but any JDK
Callable can be passed in. Do note that the runner will
not run unless triggered manually or if run-at-startup
is set to true. For more information on runners, see
the dedicated chapter.
The previous example assumes the Tool
dependencies (such as its class) are available in the classpath. If that
is not the case, tool-runner allows a jar to be
specified:
<hdp:tool-runner ... jar="myTool.jar"> ... </hdp:tool-runner>
The jar is used to instantiate and start the tool - in fact all its
dependencies are loaded from the jar meaning they no longer need to be
part of the classpath. This mechanism provides proper isolation between
tools as each of them might depend on certain libraries with different
versions; rather then adding them all into the same app (which might be
impossible due to versioning conflicts), one can simply point to the
different jars and be on her way. Note that when using a jar, if the main
class (as specified by the Main-Class
entry) is the target Tool, one can skip specifying
the tool as it will picked up automatically.
Like the rest of the SHDP elements, tool-runner
allows the passed Hadoop configuration (by default
hadoopConfiguration but specified in the example for
clarity) to be customized
accordingly; the snippet only highlights the property initialization for
simplicity but more options are available. Since usually the
Tool implementation has a default argument, one can use
the tool-class attribute. However it is possible to
refer to another Tool instance or declare a nested
one:
<hdp:tool-runner id="someTool" run-at-startup="true"> <hdp:tool> <bean class="org.foo.AnotherTool" p:input="data/in.txt" p:output="data/out.txt"/> </hdp:tool> </hdp:tool-runner>
This is quite convenient if the Tool class
provides setters or richer constructors. Note that by default the
tool-runner does not execute the
Tool until its definition is actually called - this
behavior can be changed through the run-at-startup
attribute above.
tool-runner is a nice way for migrating series
or shell invocations or scripts into fully wired, managed Java objects.
Consider the following shell script:
hadoop jar job1.jar -files fullpath:props.properties -Dconfig=config.properties ... hadoop jar job2.jar arg1 arg2... ... hadoop jar job10.jar ...
Each job is fully contained in the specified jar, including all the dependencies (which might conflict with the ones from other jobs). Additionally each invocation might provide some generic options or arguments but for the most part all will share the same configuration (as they will execute against the same cluster).
The script can be fully ported to SHDP, through the
tool-runner element:
<hdp:tool-runner id="job1" tool-class="job1.Tool" jar="job1.jar" files="fullpath:props.properties" properties-location="config.properties"/> <hdp:tool-runner id="job2" jar="job2.jar"> <hdp:arg value="arg1"/> <hdp:arg value="arg2"/> </hdp:tool-runner> <hdp:tool-runner id="job3" jar="job3.jar"/> ...
All the features have been explained in the previous sections but
let us review what happens here. As mentioned before, each tool gets
autowired with the hadoopConfiguration;
job1 goes beyond this and uses its own properties
instead. For the first jar, the Tool class is
specified, however the rest assume the jar
Main-Classes implement the
Tool interface; the namespace will
discover them automatically and use them accordingly. When needed (such
as with job1), additional files or libs are
provisioned in the cluster. Same thing with the job arguments.
However more things that go beyond scripting, can be applied to
this configuration - each job can have multiple properties loaded or
declared inlined - not just from the local file system, but also from
the classpath or any url for that matter. In fact, the whole
configuration can be externalized and parameterized (through Spring's
property
placeholder and/or Environment
abstraction). Moreover, each job can be ran by itself (through
the JobRunner) or as part of a workflow - either
through Spring's depends-on or the much more powerful
Spring Batch and tool-tasklet.
For Spring Batch environments, SHDP provides a dedicated tasklet
to execute Hadoop tasks as a step in a Spring Batch workflow. The
tasklet element supports the same configuration options as tool-runner except for
run-at-startup (which does not apply for a
workflow):
<hdp:tool-tasklet id="tool-tasklet" tool-ref="some-tool" />
SHDP also provides support for executing vanilla Hadoop jars. Thus the famous WordCount example:
bin/hadoop jar hadoop-examples.jar wordcount /wordcount/input /wordcount/output
becomes
<hdp:jar-runner id="wordcount" jar="hadoop-examples.jar" run-at-startup="true"> <hdp:arg value="wordcount"/> <hdp:arg value="/wordcount/input"/> <hdp:arg value="/wordcount/output"/> </hdp:jar-runner>
| Note |
|---|---|
Just like the hadoop jar command, by default the
jar support reads the jar's Main-Class if none is
specified. This can be customized through the
main-class attribute. |
Additionally the runner (just like the job runner) allows one or
multiple pre and post actions to be
specified to be executed before and after each run. Typically other
runners (such as other jobs or scripts) can be specified but any JDK
Callable can be passed in. Do note that the runner will
not run unless triggered manually or if run-at-startup
is set to true. For more information on runners, see
the dedicated chapter.
The jar support provides a nice and easy
migration path from jar invocations from the command-line to SHDP (note
that Hadoop generic options
are also supported). Especially since SHDP enables Hadoop
Configuration objects, created during the jar
execution, to automatically inherit the context Hadoop configuration. In
fact, just like other SHDP elements, the jar element
allows configurations
properties to be declared locally, just for the jar run. So for
example, if one would use the following declaration:
<hdp:jar-runner id="wordcount" jar="hadoop-examples.jar" run-at-startup="true"> <hdp:arg value="wordcount"/> ... speed=fast </hdp:jar-runner>
inside the jar code, one could do the following:
assert "fast".equals(new Configuration().get("speed"));
This enabled basic Hadoop jars to use, without changes, the enclosing application Hadoop configuration.
And while we think it is a useful feature (that is why we added it in the first place), we strongly recommend using the tool support instead or migrate to it; there are several reasons for this mainly because there are no contracts to use, leading to very poor embeddability caused by:
-
No standard
ConfigurationinjectionWhile SHDP does a best effort to pass the Hadoop configuration to the jar, there is no guarantee the jar itself does not use a special initialization mechanism, ignoring the passed properties. After all, a vanilla
Configurationis not very useful so applications tend to provide custom code to address this. -
System.exit()callsMost jar examples out there (including
WordCount) assume they are started from the command line and among other things, callSystem.exit, to shut down the JVM, whether the code is succesful or not. SHDP prevents this from happening (otherwise the entire application context would shutdown abruptly) but it is a clear sign of poor code collaboration.
SHDP tries to use sensible defaults to provide the best
integration experience possible but at the end of the day, without any
contract in place, there are no guarantees. Hence using the
Tool interface is a much better alternative.
Like for the rest of its tasks, for Spring Batch environments,
SHDP provides a dedicated tasklet to execute Hadoop jars as a step in a
Spring Batch workflow. The tasklet element supports the same
configuration options as jar-runner except for
run-at-startup (which does not apply for a
workflow):
<hdp:jar-tasklet id="jar-tasklet" jar="some-jar.jar" />
DistributedCache
is a Hadoop facility for distributing application-specific, large,
read-only files (text, archives, jars and so on) efficiently. Applications
specify the files to be cached via urls (hdfs://) using
DistributedCache and the framework will copy the
necessary files to the slave nodes before any tasks for the job are
executed on that node. Its efficiency stems from the fact that the files
are only copied once per job and the ability to cache archives which are
un-archived on the slaves. Note that DistributedCache
assumes that the files to be cached (and specified via hdfs:// urls) are
already present on the Hadoop FileSystem.
SHDP provides first-class configuration for the distributed cache
through its cache element (backed by
DistributedCacheFactoryBean class), allowing files
and archives to be easily distributed across nodes:
<hdp:cache create-symlink="true"> <hdp:classpath value="/cp/some-library.jar#library.jar" /> <hdp:cache value="/cache/some-archive.tgz#main-archive" /> <hdp:cache value="/cache/some-resource.res" /> <hdp:local value="some-file.txt" /> </hdp:cache>
The definition above registers several resources with the cache
(adding them to the job cache or classpath) and creates symlinks for them.
As described in the DistributedCache documentation,
the declaration format is (absolute-path#link-name).
The link name is determined by the URI fragment (the text following the #
such as #library.jar or
#main-archive above) - if no name is specified, the
cache bean will infer one based on the resource file name. Note that one
does not have to specify the hdfs://node:port prefix as
these are automatically determined based on the configuration wired into
the bean; this prevents environment settings from being hard-coded into
the configuration which becomes portable. Additionally based on the
resource extension, the definition differentiates between archives
(.tgz, .tar.gz,
.zip and .tar) which will be
uncompressed, and regular files that are copied as-is. As with the rest of
the namespace declarations, the definition above relies on defaults -
since it requires a Hadoop Configuration and
FileSystem objects and none are specified (through
configuration-ref and
file-system-ref) it falls back to the default naming
and is wired with the bean named hadoopConfiguration,
creating the FileSystem automatically.
![[Warning]](images/warning.png) | Warning |
|---|---|
Clients setting up a classpath in the
DistributedCache, running on Windows platforms should
set the System path.separator
property to :. Otherwise the classpath will be set
incorrectly and will be ignored; see HADOOP-9123
bug report for more information. There are multiple ways to change
the <hdp:script language="javascript" run-at-startup="true"> // set System 'path.separator' to ':' - see HADOOP-9123 java.lang.System.setProperty("path.separator", ":") </hdp:script> |
The job, streaming and
tool all support a subset of generic
options, specifically archives,
files and libs.
libs is probably the most useful as it enriches a job
classpath (typically with some jars) - however the other two allow
resources or archives to be copied throughout the cluster for the job to
consume. Whenver faced with provisioning issues, revisit these options as
they can help up significantly. Note that the fs,
jt or conf options are not supported
- these are designed for command-line usage, for bootstrapping the
application. This is no longer needed, as the SHDP offers first-class
support for defining and customizing Hadoop configurations.
A common task in Hadoop is interacting with its file system, whether for provisioning, adding new files to be processed, parsing results, or performing cleanup. Hadoop offers several ways to achieve that:
one can use its Java API (namely FileSystem) or
use the hadoop command line, in particular the file system shell. However there is no middle ground,
one either has to use the (somewhat verbose, full of checked exceptions) API or fall back to the command line, outside the application. SHDP addresses this issue by bridging the two worlds, exposing both the
FileSystem and the fs shell through an intuitive, easy-to-use Java API. Add your favorite JVM scripting language right
inside your Spring for Apache Hadoop application and you have a powerful combination.
The Hadoop file-system, HDFS, can be accessed in various ways - this section will cover the most popular protocols for interacting with HDFS and their pros and cons. SHDP does not enforce any specific protocol
to be used - in fact, as described in this section any FileSystem implementation can be used, allowing even other implementations than HDFS to be used.
The table below describes the common HDFS APIs in use:
Table 4.1. HDFS APIs
| File System | Comm. Method | Scheme / Prefix | Read / Write | Cross Version |
|---|---|---|---|---|
| HDFS | RPC | hdfs:// | Read / Write | Same HDFS version only |
| HFTP | HTTP | hftp:// | Read only | Version independent |
| WebHDFS | HTTP (REST) | webhdfs:// | Read / Write | Version independent |
hdfs:// protocol should be familiar to most readers - most docs (and in fact the previous chapter as well) mention it. It works out of the box and it's fairly efficient. However because it is
RPC based, it requires both the client and the Hadoop cluster to share the same version. Upgrading one without the other causes serialization errors meaning the client cannot interact with the cluster. As an alternative
one can use hftp:// which is HTTP-based or its more secure brother hsftp:// (based on SSL) which gives you a version independent protocol meaning you can use it to interact
with clusters with an unknown or different version than that of the client. hftp is read only (write operations will fail right away) and it is typically used with disctp for
reading data. webhdfs:// is one of the additions in Hadoop 1.0 and is a mixture between hdfs and hftp protocol - it provides a version-independent, read-write,
REST-based protocol which means that you can read and write to/from Hadoop clusters no matter their version. Furthermore, since webhdfs:// is backed by a REST API, clients in other languages can
use it with minimal effort.
| Note |
|---|---|
|
Not all file systems work out of the box. For example WebHDFS needs to be enabled first in the cluster (through |
Once the scheme has been decided upon, one can specify it through the standard Hadoop configuration, either through the Hadoop configuration files or its properties:
<hdp:configuration> fs.default.name=webhdfs://localhost ... </hdp:configuration>
This instructs Hadoop (and automatically SHDP) what the default, implied file-system is. In SHDP, one can create additional file-systems (potentially to connect to other clusters) and specify a different scheme:
<!-- manually creates the default SHDP file-system named 'hadoopFs' --> <hdp:file-system uri="webhdfs://localhost"/> <!-- creates a different FileSystem instance --> <hdp:file-system id="old-cluster" uri="hftp://old-cluster/"/>
As with the rest of the components, the file systems can be injected where needed - such as file shell or inside scripts (see the next section).
Since Hadoop is written in Java, accessing its APIs in a native way provides maximum control and flexibility over the interaction with Hadoop. This holds true for working with
its file systems; in fact all the other tools that one might use are built upon these. The main entry point is the org.apache.hadoop.fs.FileSystem abstract class which provides the
foundation of most (if not all) of the actual file system implementations out there. Whether one is using a local, remote or distributed store through the FileSystem API she
can query and manipulate the available resources or create new ones. To do so however, one needs to write Java code, compile the classes and configure them which is somewhat cumbersome especially when
performing simple, straightforward operations (like copy a file or delete a directory).
JVM scripting languages (such as Groovy, JRuby, Jython or Rhino to name just a few) provide a nice solution to the Java language; they run on the JVM, can interact with the Java code with no or few changes or restrictions and have a nicer, simpler, less ceremonial syntax; that is, there is no need to define a class or a method - simply write the code that you want to execute and you are done. SHDP combines the two, taking care of the configuration and the infrastructure so one can interact with the Hadoop environment from her language of choice.
Let us take a look at a JavaScript example using Rhino (which is part of JDK 6 or higher, meaning one does not need any extra libraries):
<beans xmlns="http://www.springframework.org/schema/beans" ...> <hdp:configuration .../> <hdp:script id="inlined-js" language="javascript" run-at-startup="true"> importPackage(java.util); name = UUID.randomUUID().toString() scriptName = "src/test/resources/test.properties" // fs - FileSystem instance based on 'hadoopConfiguration' bean // call FileSystem#copyFromLocal(Path, Path) fs.copyFromLocalFile(scriptName, name) // return the file length fs.getLength(name) </hdp:script> </beans>
The script element, part of the SHDP namespace, builds on top of the scripting support in Spring permitting script declarations to be evaluated and declared as normal bean definitions. Furthermore it automatically exposes Hadoop-specific objects, based on the existing configuration, to the script such as the FileSystem (more on that in the next section). As one can see, the script
is fairly obvious: it generates a random name (using the UUID class from java.util package) and then copies a local file into HDFS under the random name. The last line returns
the length of the copied file which becomes the value of the declaring bean (in this case inlined-js) - note that this might vary based on the scripting engine used.
| Note |
|---|---|
The attentive reader might have noticed that the arguments passed to the FileSystem object are not of type Path but rather String. To avoid
the creation of Path object, SHDP uses a wrapper class (SimplerFileSystem) which automatically does the conversion so you don't have to. For more information see the
implicit variables section. |
Note that for inlined scripts, one can use Spring's property placeholder configurer to automatically expand variables at runtime. Using one of the examples seen before:
<beans ... > <context:property-placeholder location="classpath:hadoop.properties" /> <hdp:script language="javascript" run-at-startup="true"> ... tracker=${hd.fs} ... </hdp:script> </beans>
Notice how the script above relies on the property placeholder to expand ${hd.fs} with the values from hadoop.properties file available in the classpath.
As you might have noticed, the script element defines a runner for JVM scripts. And just like the rest of the SHDP runners, it allows one or multiple
pre and post actions to be specified to be executed before and after each run.
Typically other runners (such as other jobs or scripts) can be specified but any JDK Callable can be
passed in. Do note that the runner will not run unless triggered manually or if run-at-startup is set to true.
For more information on runners, see the dedicated chapter.
Inlined scripting is quite handy for doing simple operations and coupled with the property expansion is quite a powerful tool that can handle a variety of use cases. However when more logic is required or the script is affected by XML formatting, encoding or syntax restrictions (such as Jython/Python for which white-spaces are important) one should consider externalization. That is, rather than declaring the script directly inside the XML, one can declare it in its own file. And speaking of Python, consider the variation of the previous example:
<hdp:script location="org/company/basic-script.py" run-at-startup="true"/>
The definition does not bring any surprises but do notice there is no need to specify the language (as in the case of a inlined declaration)
since script extension (py) already provides that information. Just for completeness, the basic-script.py looks as follows:
from java.util import UUID from org.apache.hadoop.fs import Path print "Home dir is " + str(fs.homeDirectory) print "Work dir is " + str(fs.workingDirectory) print "/user exists " + str(fs.exists("/user")) name = UUID.randomUUID().toString() scriptName = "src/test/resources/test.properties" fs.copyFromLocalFile(scriptName, name) print Path(name).makeQualified(fs)
To ease the interaction of the script with its enclosing context, SHDP binds by default the so-called implicit variables. These are:
Table 4.2. Implicit variables
| Name | Type | Description |
|---|---|---|
| cfg | org.apache.hadoop.conf.Configuration | Hadoop Configuration (relies on hadoopConfiguration bean or singleton type match) |
| cl | java.lang.ClassLoader | ClassLoader used for executing the script |
| ctx | org.springframework.context.ApplicationContext | Enclosing application context |
| ctxRL | org.springframework.io.support.ResourcePatternResolver | Enclosing application context ResourceLoader |
| distcp | org.springframework.data.hadoop.fs.DistributedCopyUtil | Programmatic access to DistCp |
| fs | org.apache.hadoop.fs.FileSystem | Hadoop File System (relies on 'hadoop-fs' bean or singleton type match, falls back to creating one based on 'cfg') |
| fsh | org.springframework.data.hadoop.fs.FsShell | File System shell, exposing hadoop 'fs' commands as an API |
| hdfsRL | org.springframework.data.hadoop.io.HdfsResourceLoader | Hdfs resource loader (relies on 'hadoop-resource-loader' or singleton type match, falls back to creating one automatically based on 'cfg') |
| Note |
|---|---|
If no Hadoop Configuration can be detected (either by name hadoopConfiguration or by type), several log warnings will be made and none of the Hadoop-based variables (namely
cfg, distcp, fs, fsh, distcp or hdfsRL) will be bound.
|
As mentioned in the Description column, the variables are first looked (either by name or by type) in the application context and, in case they are missing, created on the spot based on
the existing configuration. Note that it is possible to override or add new variables to the scripts through the property sub-element that can set values or references to other beans:
<hdp:script location="org/company/basic-script.js" run-at-startup="true"> <hdp:property name="foo" value="bar"/> <hdp:property name="ref" ref="some-bean"/> </hdp:script>
The script namespace provides various options to adjust its behaviour depending on the script content. By default the script is simply declared - that is, no execution occurs.
One however can change that so that the script gets evaluated at startup (as all the examples in this section do) through the run-at-startup flag
(which is by default false) or when invoked manually
(through the Callable).
Similarily, by default the script gets evaluated on each run. However for scripts that are expensive and return the same
value every time one has various caching options, so the evaluation occurs only when needed through the evaluate attribute:
Table 4.3. script attributes
| Name | Values | Description |
|---|---|---|
run-at-startup | false(default), true | Wether the script is executed at startup or not |
evaluate | ALWAYS(default), IF_MODIFIED, ONCE | Wether to actually evaluate the script when invoked or used a previous value. ALWAYS means evaluate every time, IF_MODIFIED evaluate if the backing
resource (such as a file) has been modified in the meantime and ONCE only once. |
For Spring Batch environments, SHDP provides a dedicated tasklet to execute scripts.
<script-tasklet id="script-tasklet"> <script language="groovy"> inputPath = "/user/gutenberg/input/word/" outputPath = "/user/gutenberg/output/word/" if (fsh.test(inputPath)) { fsh.rmr(inputPath) } if (fsh.test(outputPath)) { fsh.rmr(outputPath) } inputFile = "src/main/resources/data/nietzsche-chapter-1.txt" fsh.put(inputFile, inputPath) </script> </script-tasklet>
The tasklet above embedds the script as a nested element. You can also declare a reference to another script definition, using the script-ref attribute which allows you to externalize the scripting code to an external resource.
<script-tasklet id="script-tasklet" script-ref="clean-up"/> <hdp:script id="clean-up" location="org/company/myapp/clean-up-wordcount.groovy"/>
A handy utility provided by the Hadoop distribution is the file system shell which allows UNIX-like commands to be
executed against HDFS. One can check for the existence of files, delete, move, copy directories or files or set up permissions. However the utility is only available from the command-line which makes it hard
to use from/inside a Java application. To address this problem, SHDP provides a lightweight, fully embeddable shell, called FsShell which mimics most of the commands available from the command line:
rather than dealing with System.in or System.out, one deals with objects.
Let us take a look at using FsShell by building on the previous scripting examples:
<hdp:script location="org/company/basic-script.groovy" run-at-startup="true"/>
name = UUID.randomUUID().toString() scriptName = "src/test/resources/test.properties" fs.copyFromLocalFile(scriptName, name) // use the shell made available under variable fsh dir = "script-dir" if (!fsh.test(dir)) { fsh.mkdir(dir); fsh.cp(name, dir); fsh.chmodr(700, dir) println "File content is " + fsh.cat(dir + name).toString() } println fsh.ls(dir).toString() fsh.rmr(dir)
As mentioned in the previous section, a FsShell instance is automatically created and configured for scripts, under the name fsh.
Notice how the entire block relies on the usual commands: test, mkdir, cp and so on.
Their semantics are exactly the same as in the command-line version however one has access to a native Java API that returns
actual objects (rather than Strings) making it easy to use them programmatically whether in Java or another language. Furthermore, the class offers enhanced methods (such as chmodr
which stands for recursive chmod) and multiple overloaded methods taking advantage of varargs
so that multiple parameters can be specified. Consult the API for more information.
To be as close as possible to the command-line shell, FsShell mimics even the messages being displayed. Take a look at line 9 which prints the result of fsh.cat(). The
method returns a Collection of Hadoop Path objects (which one can use programatically). However when invoking toString on the collection, the same printout as from
the command-line shell is being displayed:
File content is some text
The same goes for the rest of the methods, such as ls. The same script in JRuby would look something like this:
require 'java' name = java.util.UUID.randomUUID().to_s scriptName = "src/test/resources/test.properties" $fs.copyFromLocalFile(scriptName, name) # use the shell dir = "script-dir/" ... print $fsh.ls(dir).to_s
which prints out something like this:
drwx------ - user supergroup 0 2012-01-26 14:08 /user/user/script-dir -rw-r--r-- 3 user supergroup 344 2012-01-26 14:08 /user/user/script-dir/520cf2f6-a0b6-427e-a232-2d5426c2bc4e
As you can see, not only can you reuse the existing tools and commands with Hadoop inside SHDP, but you can also code against them in various scripting languages. And as you might have noticed, there is no special configuration required - this is automatically inferred from the enclosing application context.
| Note |
|---|---|
The careful reader might have noticed that besides the syntax, there are some minor differences in how the various languages interact with the java objects. For example the automatic toString
call called in Java for doing automatic String conversion is not necessarily supported (hence the to_s in Ruby or str in Python). This is to be expected
as each language has its own semantics - for the most part these are easy to pick up but do pay attention to details. |
Similar to the FsShell, SHDP provides a lightweight, fully embeddable DistCp version
that builds on top of the distcp from the Hadoop distro. The semantics and configuration options are the same however, one can use it from within a Java application without having to use
the command-line. See the API for more information:
<hdp:script language="groovy">distcp.copy("${distcp.src}", "${distcp.dst}")</hdp:script>
The bean above triggers a distributed copy relying again on Spring's property placeholder variable expansion for its source and destination.
SHDP provides basic configuration for HBase through the hbase-configuration namespace element (or its backing
HbaseConfigurationFactoryBean).
<!-- default bean id is 'hbaseConfiguration' that uses the existing 'hadoopCconfiguration' object --> <hdp:hbase-configuration configuration-ref="hadoopCconfiguration" />
The above declaration does more than easily create an HBase configuration object; it will also manage the backing HBase connections: when the application
context shuts down, so will any HBase connections opened - this behavior can be adjusted through the stop-proxy and delete-connection attributes:
<!-- delete associated connections but do not stop the proxies --> <hdp:hbase-configuration stop-proxy="false" delete-connection="true"> foo=bar property=value </hdp:hbase-configuration>
Additionally, one can specify the ZooKeeper port used by the HBase server - this is especially useful when connecting to a remote instance (note one can fully configure HBase including the ZooKeeper host and port through properties; the attributes here act as shortcuts for easier declaration):
<!-- specify ZooKeeper host/port --> <hdp:hbase-configuration zk-quorum="${hbase.host}" zk-port="${hbase.port}">
Notice that like with the other elements, one can specify additional properties specific to this configuration. In fact hbase-configuration provides the same properties
configuration knobs as hadoop configuration:
<hdp:hbase-configuration properties-ref="some-props-bean" properties-location="classpath:/conf/testing/hbase.properties"/>
One of the most popular and powerful feature in Spring Framework is the Data Access Object (or DAO) support. It makes dealing with data access technologies easy and consistent allowing easy switch or interconnection of the aforementioned persistent stores with minimal friction (no worrying about catching exceptions, writing boiler-plate code or handling resource acquisition and disposal). Rather than reiterating here the value proposal of the DAO support, we recommend the DAO section in the Spring Framework reference documentation
SHDP provides the same functionality for Apache HBase through its org.springframework.data.hadoop.hbase package: an HbaseTemplate along with several callbacks
such as TableCallback, RowMapper and ResultsExtractor that remove the low-level, tedious details for finding the HBase table, run the query, prepare the scanner,
analyze the results then clean everything up, letting the developer focus on her actual job (users familiar with Spring should find the class/method names quite familiar).
At the core of the DAO support lies HbaseTemplate - a high-level abstraction for interacting with HBase. The template requires an HBase configuration, once it's
set, the template is thread-safe and can be reused across multiple instances at the same time:
// default HBase configuration <hdp:hbase-configuration/> // wire hbase configuration (using default name 'hbaseConfiguration') into the template <bean id="htemplate" class="org.springframework.data.hadoop.hbase.HbaseTemplate" p:configuration-ref="hbaseConfiguration"/>
The template provides generic callbacks, for executing logic against the tables or doing result or row extraction, but also utility methods (the so-called one-liners) for common operations. Below are some examples of how the template usage looks like:
// writing to 'MyTable' template.execute("MyTable", new TableCallback<Object>() { @Override public Object doInTable(HTable table) throws Throwable { Put p = new Put(Bytes.toBytes("SomeRow")); p.add(Bytes.toBytes("SomeColumn"), Bytes.toBytes("SomeQualifier"), Bytes.toBytes("AValue")); table.put(p); return null; } });
// read each row from 'MyTable' List<String> rows = template.find("MyTable", "SomeColumn", new RowMapper<String>() { @Override public String mapRow(Result result, int rowNum) throws Exception { return result.toString(); } }));
The first snippet showcases the generic TableCallback - the most generic of the callbacks, it does the table lookup and resource cleanup so that the user code does not have to.
Notice the callback signature - any exception thrown by the HBase API is automatically caught, converted to Spring's
DAO exceptions and resource clean-up applied transparently.
The second example, displays the dedicated lookup methods - in this case find which, as the name implies, finds all the rows matching the given criteria and allows user code to be executed against each
of them (typically for doing some sort of type conversion or mapping). If the entire result is required, then one can use ResultsExtractor instead of RowMapper.
Besides the template, the package offers support for automatically binding HBase table to the current thread through HbaseInterceptor and HbaseSynchronizationManager.
That is, each class that performs DAO operations on HBase can be wrapped
by HbaseInterceptor so that each table in use, once found, is bound to the thread so any subsequent call to it avoids the lookup. Once the call ends, the table is automatically closed so there is
no leakage between requests. Please refer to the Javadocs for more information.
When working with http://hive.apache.org from a Java environment, one can choose between the Thrift client or using the Hive JDBC-like driver. Both have their pros and cons but no matter the choice, Spring and SHDP support both of them.
SHDP provides a dedicated namespace element for starting a Hive server as a Thrift service (only when using Hive 0.8 or higher). Simply specify the host, the port
(the defaults are localhost and 10000 respectively) and you're good to go:
<!-- by default, the definition name is 'hive-server' --> <hdp:hive-server host="some-other-host" port="10001" />
If needed the Hadoop configuration can be passed in or additional properties specified. In fact hiver-server provides the same properties configuration knobs
as hadoop configuration:
<hdp:hive-server host="some-other-host" port="10001" properties-location="classpath:hive-dev.properties" configuration-ref="hadoopConfiguration"> someproperty=somevalue hive.exec.scratchdir=/tmp/mydir </hdp:hive-server>
The Hive server is bound to the enclosing application context life-cycle, that is it will automatically startup and shutdown along-side the application context.
Similar to the server, SHDP provides a dedicated namespace element for configuring a Hive client (that is Hive accessing a server node through the Thrift). Likewise, simply specify the host, the port
(the defaults are localhost and 10000 respectively) and you're done:
<!-- by default, the definition name is 'hiveClientFactory' --> <hdp:hive-client-factory host="some-other-host" port="10001" />
Note that since Thrift clients are not thread-safe, hive-client-factory returns a factory (named org.springframework.data.hadoop.hive.HiveClientFactory)
for creating HiveClient new instances for each invocation. Furthermore, the client definition
also allows Hive scripts (either declared inlined or externally) to be executed during initialization, once the client connects; this is quite useful for doing Hive specific initialization:
<hive-client-factory host="some-host" port="some-port" xmlns="http://www.springframework.org/schema/hadoop"> <hdp:script> DROP TABLE IF EXITS testHiveBatchTable; CREATE TABLE testHiveBatchTable (key int, value string); </hdp:script> <hdp:script location="classpath:org/company/hive/script.q"> <arguments>ignore-case=true</arguments> </hdp:script> </hive-client-factory>
In the example above, two scripts are executed each time a new Hive client is created (if the scripts need to be executed only once consider using a tasklet) by the factory. The first script is defined inline while the second is read from the classpath and passed one parameter. For more information on using parameters (or variables) in Hive scripts, see this section in the Hive manual.
Another attractive option for accessing Hive is through its JDBC driver. This exposes Hive through the JDBC API meaning one can use the standard API or its derived utilities to interact with Hive, such as the rich JDBC support in Spring Framework.
| Warning |
|---|---|
|
Note that the JDBC driver is a work-in-progress and not all the JDBC features are available (and probably never will since Hive cannot support all of them as it is not the typical relational database). Do read the official documentation and examples. |
SHDP does not offer any dedicated support for the JDBC integration - Spring Framework itself provides the needed tools; simply configure Hive as you would with any other JDBC Driver:
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:c="http://www.springframework.org/schema/c" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"> <!-- basic Hive driver bean --> <bean id="hive-driver" class="org.apache.hadoop.hive.jdbc.HiveDriver"/> <!-- wrapping a basic datasource around the driver --> <!-- notice the 'c:' namespace (available in Spring 3.1+) for inlining constructor arguments, in this case the url (default is 'jdbc:hive://localhost:10000/default') --> <bean id="hive-ds" class="org.springframework.jdbc.datasource.SimpleDriverDataSource" c:driver-ref="hive-driver" c:url="${hive.url}"/> <!-- standard JdbcTemplate declaration --> <bean id="template" class="org.springframework.jdbc.core.JdbcTemplate" c:data-source-ref="hive-ds"/> <context:property-placeholder location="hive.properties"/> </beans>
And that is it! Following the example above, one can use the hive-ds DataSource bean to manually get a hold of Connections
or better yet, use Spring's JdbcTemplate as in the example above.
Like the rest of the Spring Hadoop components, a runner is provided out of the box for executing Hive scripts, either inlined or from various locations through hive-runner element:
<hdp:hive-runner id="hiveRunner" run-at-startup="true"> <hdp:script> DROP TABLE IF EXITS testHiveBatchTable; CREATE TABLE testHiveBatchTable (key int, value string); </hdp:script> <hdp:script location="hive-scripts/script.q"/> </hdp:hive-runner>
The runner will trigger the execution during the application start-up (notice
the run-at-startup flag which is by default false). Do note that the runner will not run unless triggered manually or if run-at-startup is set to true.
Additionally the runner (as in fact do all runners in SHDP) allows one or
multiple pre and post actions to be specified to be executed before and after each run. Typically other runners (such as other jobs or scripts) can be specified but any JDK Callable can be
passed in. For more information on runners, see the dedicated chapter.
For Spring Batch environments, SHDP provides a dedicated tasklet to execute Hive queries, on demand, as part of a batch or workflow. The declaration is pretty straightforward:
<hdp:hive-tasklet id="hive-script"> <hdp:script> DROP TABLE IF EXITS testHiveBatchTable; CREATE TABLE testHiveBatchTable (key int, value string); </hdp:script> <hdp:script location="classpath:org/company/hive/script.q" /> </hdp:hive-tasklet>
The tasklet above executes two scripts - one declared as part of the bean definition followed by another located on the classpath.
For those that need to programmatically interact with the Hive API, Spring for Apache Hadoop provides a dedicated template, similar to the
aforementioned JdbcTemplate. The template handles the redundant, boiler-plate code, required for interacting with Hive such as creating a new HiveClient, executing the queries,
catching any exceptions and performing clean-up. One can programmatically execute queries (and get the raw results or convert them to longs or ints) or scripts but also interact with the Hive API through the HiveClientCallback.
For example:
<hdp:hive-client-factory ... /> <!-- Hive template wires automatically to 'hiveClientFactory'--> <hdp:hive-template /> <!-- wire hive template into a bean --> <bean id="someBean" class="org.SomeClass" p:hive-template-ref="hiveTemplate"/>
public class SomeClass { private HiveTemplate template; public void setHiveTemplate(HiveTemplate template) { this.template = template; } public List<String> getDbs() { return hiveTemplate.execute(new HiveClientCallback<List<String>>() { @Override public List<String> doInHive(HiveClient hiveClient) throws Exception { return hiveClient.get_all_databases(); } })); } }
The example above shows a basic container configuration wiring a HiveTemplate into a user class which uses it to interact with the HiveClient Thrift API. Notice that the
user does not have to handle the lifecycle of the HiveClient instance or catch any exception (out of the many thrown by Hive itself and the Thrift fabric) - these are handled automatically by the template
which converts them, like the rest of the Spring templates, into DataAccessExceptions. Thus the application only has to track only one exception hierarchy across all data technologies instead of
one per technology.
For Pig users, SHDP provides easy creation and configuration of PigServer instances for registering and executing scripts either locally
or remotely. In its simplest form, the declaration looks as follows:
<hdp:pig />
This will create a org.springframework.data.hadoop.pig.PigServerFactory instance, named pigFactory, a factory that creates PigServer instances on demand
configured with a default PigContext, executing scripts in MapReduce mode. The factory is needed since PigServer is not thread-safe and thus cannot
be used by multiple objects at the same time.
In typical scenarios however, one might want to connect to a remote Hadoop tracker and register some scripts automatically so let us take a look of how the configuration might look like:
<pig-factory exec-type="LOCAL" job-name="pig-script" configuration-ref="hadoopConfiguration" properties-location="pig-dev.properties" xmlns="http://www.springframework.org/schema/hadoop"> source=${pig.script.src} <script location="org/company/pig/script.pig"> <arguments>electric=sea</arguments> </script> <script> A = LOAD 'src/test/resources/logs/apache_access.log' USING PigStorage() AS (name:chararray, age:int); B = FOREACH A GENERATE name; DUMP B; </script> </pig-factory> />
The example exposes quite a few options so let us review them one by one. First the top-level pig definition configures the pig instance: the execution type, the Hadoop configuration used and the job name. Notice that
additional properties can be specified (either by declaring them inlined or/and loading them from an external file) - in fact, <hdp:pig-factory/> just like the rest of the libraries configuration
elements, supports common properties attributes as described in the hadoop configuration section.
The definition contains also two scripts: script.pig (read from the classpath) to which one pair of arguments,
relevant to the script, is passed (notice the use of property placeholder) but also an inlined script, declared as part of the definition, without any arguments.
As you can tell, the pig-factory namespace offers several options pertaining to Pig configuration.
Like the rest of the Spring Hadoop components, a runner is provided out of the box for executing Pig scripts, either inlined or from various locations through pig-runner element:
<hdp:pig-runner id="pigRunner" run-at-startup="true"> <hdp:script> A = LOAD 'src/test/resources/logs/apache_access.log' USING PigStorage() AS (name:chararray, age:int); ... </hdp:script> <hdp:script location="pig-scripts/script.pig"/> </hdp:pig-runner>
The runner will trigger the execution during the application start-up (notice
the run-at-startup flag which is by default false). Do note that the runner will not run unless triggered manually or if run-at-startup is set to true.
Additionally the runner (as in fact do all runners in SHDP) allows one or
multiple pre and post actions to be specified to be executed before and after each run. Typically other runners (such as other jobs or scripts) can be specified but any JDK Callable can be
passed in. For more information on runners, see the dedicated chapter.
For Spring Batch environments, SHDP provides a dedicated tasklet to execute Pig queries, on demand, as part of a batch or workflow. The declaration is pretty straightforward:
<hdp:pig-tasklet id="pig-script"> <hdp:script location="org/company/pig/handsome.pig" /> </hdp:pig-tasklet>
The syntax of the scripts declaration is similar to that of the pig namespace.
For those that need to programmatically interact directly with Pig , Spring for Apache Hadoop provides a dedicated template,
similar to the aforementioned HiveTemplate. The template handles the redundant, boiler-plate code, required for interacting with Pig such as creating a new PigServer,
executing the scripts, catching any exceptions and performing clean-up. One can programmatically execute scripts but also interact with the Hive API through the PigServerCallback.
For example:
<hdp:pig-factory ... /> <!-- Pig template wires automatically to 'pigFactory'--> <hdp:pig-template /> <!-- use component scanning--> <context:component-scan base-package="some.pkg" />
public class SomeClass { @Inject private PigTemplate template; public Set<String> getDbs() { return pigTemplate.execute(new PigCallback<Set<String>() { @Override public Set<String> doInPig(PigServer pig) throws ExecException, IOException { return pig.getAliasKeySet(); } }); } }
The example above shows a basic container configuration wiring a PigTemplate into a user class which uses it to interact with the PigServer API. Notice that the
user does not have to handle the lifecycle of the PigServer instance or catch any exception - these are handled automatically by the template
which converts them, like the rest of the Spring templates, into DataAccessExceptions. Thus the application only has to track only one exception hierarchy across all data technologies instead of
one per technology.
SHDP provides basic support for Cascading library through the org.springframework.data.hadoop.cascading package -
one can create Flows or Cascades, either through XML or/and Java and execute them, either in a simplistic manner or as part of a Spring Batch job.
In addition, dedicated Taps for Spring environments are available.
As Cascading is aimed at code configuration, typically one would configure the library programatically. Such code can easily be integrated into Spring in various ways - through
factory methods or
@Configuration and @Bean (see this chapter
for more information). In short one uses Java code (or any JVM language for that matter) to create beans.
For example, looking at the official Cascading sample (Cascading for the Impatient, Part2) one can simply call the Cascading setup method from within the Spring container (original vs updated):
public class Impatient { public static FlowDef createFlowDef(String docPath, String wcPath) { // create source and sink taps Tap docTap = new Hfs(new TextDelimited(true, "\t"), docPath); Tap wcTap = new Hfs(new TextDelimited(true, "\t"), wcPath); // specify a regex operation to split the "document" text lines into a token stream Fields token = new Fields("token"); Fields text = new Fields("text"); RegexSplitGenerator splitter = new RegexSplitGenerator(token, "[ \\[\\]\\(\\),.]"); // only returns "token" Pipe docPipe = new Each("token", text, splitter, Fields.RESULTS); // determine the word counts Pipe wcPipe = new Pipe("wc", docPipe); wcPipe = new GroupBy(wcPipe, token); wcPipe = new Every(wcPipe, Fields.ALL, new Count(), Fields.ALL); // connect the taps, pipes, etc., into a flow FlowDef flowDef = FlowDef.flowDef().setName("wc").addSource(docPipe, docTap).addTailSink(wcPipe, wcTap); return flowDef; } }
The entire Cascading configuration (defining the Flow) is encapsulated within one method, which can be called by the container:
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:hdp="http://www.springframework.org/schema/hadoop" xmlns:c="http://www.springframework.org/schema/c" xmlns:p="http://www.springframework.org/schema/p" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/hadoop http://www.springframework.org/schema/hadoop/spring-hadoop.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"> <!-- factory-method approach called with two parameters available as property placeholders --> <bean id="flowDef" class="impatient.Main" factory-method="createFlowDef" c:_0="${in}" c:_1="${out}"/> <hdp:cascading-flow id="wc" definition-ref="flowDef" write-dot="dot/wc.dot"/> <hdp:cascading-cascade id="cascade" flow-ref="wc"/> <hdp:cascading-runner unit-of-work-ref="cascade" run-at-startup="true"/> </beans>
Note that no jar needs to be setup - the Cascading namespace (in particular cascading-flow, backed by HadoopFlowFactoryBean) tries to automatically setup the
resulting job classpath. By default, it will automatically add the Cascading library and its dependency to Hadoop DistributedCache so that when the job runs inside the Hadoop
cluster, the jars are properly found. When using custom jars (for example to add custom Cascading functions) or when running against a cluster that is already provisioned, one can customize this
behaviour through the jar-setup, jar and jar-by-class. For Cascading users, these settings are the equivalent of the
AppProps.setApplicationJarClass().
Furthermore, one can break down the configuration method in multiple pieces which is useful for reusing the components between multiple flows/cascades. This goes hand in hand with Spring
@Configuration feature - see the example below that configures a Cascade pipes and taps as individual beans
(see the original example):
@Configuration public class CascadingAnalysisConfig { // fields that act as placeholders for externalized values @Value("${cascade.sec}") private String sec; @Value("${cascade.min}") private String min; @Bean public Pipe tsPipe() { DateParser dateParser = new DateParser(new Fields("ts"), "dd/MMM/yyyy:HH:mm:ss Z"); return new Each("arrival rate", new Fields("time"), dateParser); } @Bean public Pipe tsCountPipe() { Pipe tsCountPipe = new Pipe("tsCount", tsPipe()); tsCountPipe = new GroupBy(tsCountPipe, new Fields("ts")); return new Every(tsCountPipe, Fields.GROUP, new Count()); } @Bean public Pipe tmCountPipe() { Pipe tmPipe = new Each(tsPipe(), new ExpressionFunction(new Fields("tm"), "ts - (ts % (60 * 1000))", long.class)); Pipe tmCountPipe = new Pipe("tmCount", tmPipe); tmCountPipe = new GroupBy(tmCountPipe, new Fields("tm")); return new Every(tmCountPipe, Fields.GROUP, new Count()); } @Bean public Map<String, Tap> sinks(){ Tap tsSinkTap = new Hfs(new TextLine(), sec); Tap tmSinkTap = new Hfs(new TextLine(), min); return Cascades.tapsMap(Pipe.pipes(tsCountPipe(), tmCountPipe()), Tap.taps(tsSinkTap, tmSinkTap)); } @Bean public String regex() { return "^([^ ]*) +[^ ]* +[^ ]* +\\[([^]]*)\\] +\\\"([^ ]*) ([^ ]*) [^ ]*\\\" ([^ ]*) ([^ ]*).*$"; } @Bean public Fields fields() { return new Fields("ip", "time", "method", "event", "status", "size"); } }
The class above creates several objects (all part of the Cascading package) (named after the methods) which can be injected or wired just like any other bean (notice how the wiring is done between the beans by point to their methods). One can mix and match (if needed) code and XML configurations inside the same application:
<!-- code configuration class --> <bean class="org.springframework.data.hadoop.cascading.CascadingAnalysisConfig"/> <!-- Tap created through XML rather then code (using Spring's 3.1 c: namespace)--> <bean id="tap" class="cascading.tap.hadoop.Hfs" c:fields-ref="fields" c:string-path-value="${cascade.input}"/> <!-- standard bean declaration used to showcase the container flexibility --> <!-- note the tap and sinks are imported from the CascadingAnalysisConfig bean --> <bean id="analysisFlow" class="org.springframework.data.hadoop.cascading.HadoopFlowFactoryBean" p:configuration-ref="hadoopConfiguration" p:source-ref="tap" p:sinks-ref="sinks"> <property name="tails"><list> <ref bean="tsCountPipe"/> <ref bean="tmCountPipe"/> </list></property> </bean> </list></property> </bean> <hdp:cascading-cascade flow="analysisFlow" /> <hdp:cascading-runner unit-of-work-ref="cascade" run-at-startup="true"/>
The XML above, whose main purpose is to illustrate possible ways of configuring, uses SHDP classes to create a Cascade with one nested Flow using the taps
and sinks configured by the code class. Additionally it also shows how the cascade is ran (through cascading-runner).
The runner will trigger the execution during the application start-up (notice
the run-at-startup flag which is by default false). Do note that the runner will not run unless triggered manually or if run-at-startup is set to true.
Additionally the runner (as in fact do all runners in SHDP) allows one or
multiple pre and post actions to be specified to be executed before and after each run. Typically other runners (such as other jobs or scripts) can be specified but any JDK Callable can be
passed in. For more information on runners, see the dedicated chapter.
Whether XML or Java config is better is up to the user and is usually based on the type of the configuration required. Java config suits Cascading better but note that the FactoryBeans
above handle the lifecycle and some default configuration for both the Flow and Cascade objects. Either way, whatever option is used, SHDP fully supports it.
For Spring Batch environments, SHDP provides a dedicated tasklet (similar to CascadeRunner above) for executing Cascade or Flow
instances, on demand, as part of a batch or workflow. The declaration is pretty straightforward:
<hdp:tasklet p:unit-of-work-ref="cascade" />
There are quite a number of DSLs built on top of Cascading, most noteably Cascalog (written in Clojure) and Scalding (written in Scala). This documentation will cover Scalding however the same concepts can be applied across the board to all DSLs.
As with the rest of the DSLs, Scalding offers a simplified, fluent syntax for creating units of code that build on top of Cascading. This in turn translates to Map Reduce jobs that get executed on Hadoop.
Once compiled, the DSL gets translated into actual JVM classes that get executed by Scalding through its own Tool instance (namely com.twitter.scalding.Tool).
One has the option of either deploy the Scalding jobs directly (by invoking the aforementioned Tool) or use Scalding's scald.rb script which does the same thing based
on the various attributes passed to it. Both approaches can be used in SHDP, the former through the Tool support (described below) and the latter by invoking the
scald.rb script directly through the scripting feature.
For example, to run the tutorial examples (say Tutorial1), one can issue the following command:
scripts/scald.rb --local tutorial/Tutorial1.scala
which compiles Tutorial1, creates a bundled jar and runs it on a local Hadoop instance. When using the Tool support, the compilation and the library provisioning are external tasks
(just as in the case of typical Hadoop jobs). The SHDP configuration to run the tutorial looks as follows:
<!-- the tool automatically is injected with 'hadoopConfiguration' --> <hdp:tool-runner id="scalding" tool-class="com.twitter.scalding.Tool"> <hdp:arg value="tutorial/Tutorial1"/> <hdp:arg value="--local"/> </hdp:tool-runner>
Besides dedicated configuration support, SHDP also provides read-only Tap implementations useful inside Spring environments. Currently they are meant for
local use only such as testing or single-node Hadoop setups.
The Taps in org.springframework.data.hadoop.cascading.tap.local tap (pun intended) into the rich resource support from Spring Framework and Spring Integration
allowing data to flow easily in and out of a Cascading flow.
Below is a list of the type of Taps available and their backing support.
Table 8.1. Local Taps
| Tap Name | Tap Type | Backing Resource | Resource Description |
|---|---|---|---|
ResourceTap | Source | Spring Resource | classpath, file-system, URL-based or even in-memory content |
MessageSourceTap | Source | Spring Integration MessageSource | Inbound adapter for anything from arbitrary streams, FTP or JDBC to RSS/Atom and Twitter |
MessageHandlerTap | Sink | Spring Integration MessageHandler | The opposite of MessageSourceTap: Outbound adapter for Files, JMS, TCP, etc... |
Note the Taps do not require any special configuration and are fully compatible with the existing Cascading local Schemes. To wit:
<bean id="cp-txt-files" class="org.springframework.data.hadoop.cascading.tap.local.ResourceTap"> <constructor-arg><bean class="cascading.scheme.local.TextLine"/></constructor-arg> <constructor-arg><value>classpath:/data/*.txt</value></constructor-arg> </bean>
The Tap above reads all the text files in the classpath, under data folder, through Cascading TextLine. Simply wire that to a Cascading flow
(as described in the previous section) and you are good to go.
Spring for Apache Hadoop provides for each Hadoop interaction type, whether it is vanilla Map/Reduce, Cascading, Hive or Pig, a runner, a dedicated class used for declarative (or programmatic) interaction. The list below illustrates the existing runner classes for each type, their name and namespace element.
Table 9.1. Available Runners
| Type | Name | Namespace element | Description |
|---|---|---|---|
Map/Reduce Job | JobRunner | job-runner | Runner for Map/Reduce jobs, whether vanilla M/R or streaming |
Hadoop Tool | ToolRunner | tool-runner | Runner for Hadoop Tools (whether stand-alone or as jars). |
Hadoop jars | JarRunner | jar-runner | Runner for Hadoop jars. |
| Hive queries and scripts | HiveRunner | hive-runner | Runner for executing Hive queries or scripts. |
| Pig queries and scripts | PigRunner | pig-runner | Runner for executing Pig scripts. |
Cascading Cascades | CascadeRunner | - | Runner for executing Cascading Cascades. |
| JSR-223/JVM scripts | HdfsScriptRunner | script | Runner for executing JVM 'scripting' languages (implementing the JSR-223 API). |
While most of the configuration depends on the underlying type, the runners share common attributes and behaviour so one can use them in a predictive, consistent way. Below is a list of common features:
-
declaration does not imply execution
The runner allows a script, a job, a cascade to run but the execution can be triggered either programmatically or by the container at start-up.
-
run-at-startupEach runner can execute its action at start-up. By default, this flag is set to
false. For multiple or on demand execution (such as scheduling) use theCallablecontract (see below). -
JDK
CallableinterfaceEach runner implements the JDK
Callableinterface. Thus one can inject the runner into other beans or its own classes to trigger the execution (as many or as little times as she wants). -
preandpostactionsEach runner allows one or multiple, pre or/and post actions to be specified (to chain them together such as executing a job after another or perfoming clean up). Typically other runners can be used but any
Callablecan be specified. The actions will be executed before and after the main action, in the declaration order. The runner uses a fail-safe behaviour meaning, any exception will interrupt the run and will propagated immediately to the caller. -
consider Spring Batch
The runners are meant as a way to execute basic tasks. When multiple executions need to be coordinated and the flow becomes non-trivial, we strongly recommend using Spring Batch which provides all the features of the runners and more (a complete, mature framework for batch execution).
Spring for Apache Hadoop is aware of the security constraints of the running Hadoop environment and allows its components to be configured as such. For clarity, this document breaks down security into HDFS permissions and user impersonation (also known as secure Hadoop). The rest of this document discusses each component and the impact (and usage) it has on the various SHDP features.
HDFS layer provides file permissions designed to be similar to those present in *nix OS. The official guide
explains the major components but in short, the access for each file (whether it's for reading, writing or in case of directories accessing) can be restricted to certain users or groups. Depending on the
user identity (which is typically based on the host operating system), code executing against the Hadoop cluster can see or/and interact with the file-system based on these permissions. Do note that
each HDFS or FileSystem implementation can have slightly different semantics or implementation.
SHDP obeys the HDFS permissions, using the identity of the current user (by default) for interacting with the file system. In particular, the HdfsResourceLoader considers when doing pattern matching,
only the files that it's supposed to see and does not perform any privileged action. It is possible however to specify a different user, meaning the ResourceLoader interacts with HDFS
using that user's rights - however this obeys the user impersonation rules.
When using different users, it is recommended to create separate ResourceLoader instances (one per user) instead of assigning additional permissions or groups to one user -
this makes it easier to manage and wire the different HDFS views without having to modify the ACLs. Note however that when using impersonation, the ResourceLoader might
(and will typically) return restricted files that might not be consumed or seen by the callee.
Securing a Hadoop cluster can be a difficult task - each machine can have a different set of users and groups, each with different passwords. Hadoop relies on Kerberos, a ticket-based protocol for allowing nodes to communicate over a non-secure network to prove their identity to one another in a secure manner. Unfortunately there is not a lot of documentation on this topic out there. However there are some resources to get you started.
SHDP does not require any extra configuration - it simply obeys the security system in place. By default, when running inside a secure Hadoop, SHDP uses the current user (as expected).
It also supports user impersonation, that is, interacting with the Hadoop cluster with a different identity (this allows a superuser to submit job or access hdfs on behalf of another
user in a secure way, without leaking permissions). The major MapReduce components, such as job, streaming and tool as well as
pig support user impersonation through the user attribute. By default, this property is empty, meaning the current user is used - however one can specify the different
identity (also known as ugi) to be used by the target component:
<hdp:job id="jobFromJoe" user="joe" .../>
Note that the user running the application (or the current user) must have the proper kerberos credentials to be able to impersonate the target user (in this case joe).
This section provides some guidance on how one can use the Spring for Apache Hadoop project in conjunction with other Spring projects, starting with the Spring Framework itself, then Spring Batch, and then Spring Integration.
Spring for Apache Hadoop provides integration with the Spring Framework to create and run Hadoop MapReduce, Hive, and Pig jobs as well as work with HDFS and HBase. If you have simple needs to work with Hadoop, including basic scheduling, you can add the Spring for Apache Hadoop namespace to your Spring based project and get going quickly using Hadoop.
As the complexity of your Hadoop application increases, you may want to use Spring Batch to regain on the complexity of developing a large Hadoop application. Spring Batch provides an extension to the Spring programming model to support common batch job scenarios characterized by the processing of large amounts of data from flat files, databases and messaging systems. It also provides a workflow style processing model, persistent tracking of steps within the workflow, event notification, as well as administrative functionality to start/stop/restart a workflow. As Spring Batch was designed to be extended, Spring for Apache Hadoop plugs into those extensibilty points, allowing for Hadoop related processing to be a first class citizen in the Spring Batch processing model.
Another project of interest to Hadoop developers is Spring Integration. Spring Integration provides an extension of the Spring programming model to support the well-known Enterprise Integration Patterns. It enables lightweight messaging within Spring-based applications and supports integration with external systems via declarative adapters. These adapters are of particular interest to Hadoop developers, as they directly support common Hadoop use-cases such as polling a directory or FTP folder for the presence of a file or group of files. Then once the files are present, a message is sent internally to the application to do additional processing. This additional processing can be calling a Hadoop MapReduce job directly or starting a more complex Spring Batch based workflow. Similarly, a step in a Spring Batch workflow can invoke functionality in Spring Integration, for example to send a message though an email adapter.
No matter if you use the Spring Batch project with the Spring Framework by itself or with additional extentions such as Spring Batch and Spring Integration that focus on a particular domain, you will benefit from the core values that Spring projects bring to the table, namely enabling modularity, reuse and extensive support for unit and integration testing.
Spring Batch integrates with a variety of job schedulers and is not a scheduling framework. There are many good enterprise schedulers available in both the commercial and open source spaces such as Quartz, Tivoli, Control-M, etc. It is intended to work in conjunction with a scheduler, not replace a scheduler. As a lightweight solution, you can use Spring's built in scheduling support that will give you cron-like and other basic scheduling trigger functionality. See the Task Execution and Scheduling documention for more info. A middle ground it to use Spring's Quartz integration, see Using the OpenSymphony Quartz Scheduler for more information. The Spring Batch distribution contains an example, but this documentation will be updated to provide some more directed examples with Hadoop, check for updates on the main web site of Spring for Apache Hadoop.
Spring Batch lets you attach listeners at the job and step levels to perform additional processing. For example, at the end of a job you can perform some notification or perhaps even start another Spring Batch job. As a brief example, implement the interface JobExecutionListener and configure it into the Spring Batch job as shown below.
<batch:job id="job1"> <batch:step id="import" next="wordcount"> <batch:tasklet ref="script-tasklet"/> </batch:step> <batch:step id="wordcount"> <batch:tasklet ref="wordcount-tasklet" /> </batch:step> <batch:listeners> <batch:listener ref="simpleNotificatonListener"/> </batch:listeners> </batch:job> <bean id="simpleNotificatonListener" class="com.mycompany.myapp.SimpleNotificationListener"/>
The sample applications have been moved into their own repository so they can be developed independently of the Spring for Apache Hadoop release cycle. They can be found on GitHub https://github.com/SpringSource/spring-hadoop-samples.
The wiki page for the Spring for Apache Hadoop project has more documentation for building and running the examples.
In addition to this reference documentation, there are a number of other resources that may help you learn how to use Hadoop and Spring framework. These additional, third-party resources are enumerated in this section.
- Spring for Apache Hadoop - http://www.springframework.org/spring-data/hadoop
- Spring Data - http://www.springframework.org/spring-data
- Spring Data Book - http://shop.oreilly.com/product/0636920024767.do
- SpringSource - http://blog.springsource.com/
- Apache Hadoop - http://hadoop.apache.org/
- Pivotal HD - http://gopivotal.com/pivotal-products/pivotal-data-fabric/pivotal-hd
A popular option for creating on-demand Hadoop cluster is Amazon Elastic Map Reduce or Amazon EMR service. The user can through the command-line, API or a web UI configure, start, stop and manage a Hadoop cluster in the cloud without having to worry about the actual set-up or hardware resources used by the cluster. However, as the setup is different then a locally available cluster, so does the interaction between the application that want to use it and the target cluster. This section provides information on how to setup Amazon EMR with Spring for Apache Hadoop so the changes between a using a local, pseudo-distributed or owned cluster and EMR are minimal.
![[Important]](images/important.png) | Important |
|---|---|
| This chapter assumes the user is familiar with Amazon EMR and the cost associated with it and its related services - we strongly recommend getting familiar with the official EMR documentation. |
One of the big differences when using Amazon EMR versus a local cluster is the lack of access of the file system server and the job tracker. This means submitting jobs or reading and writing to the file-system isn't available out of the box - which is understandable for security reasons. If the cluster would be open, if could be easily abused while charging its rightful owner. However, it is fairly straight-forward to get access to both the file system and the job tracker so the deployment flow does not have to change.
Amazon EMR allows clusters to be created through the management console, through the API or the command-line. This documentation will focus on the command-line but the setup is not limited to it - feel free to adjust it according to your needs or preference. Make sure to properly setup the credentials so that the S3 file-system can be properly accessed.
| Important |
|---|---|
| Make sure you read the whole chapter before starting up the EMR cluster |
A nice feature of Amazon EMR is starting a cluster for an indefinite period. That is rather then submitting a job and creating the cluster until it finished, one can create a cluster (along side a job) but request
to be kept alive even if there is no work for it. This is easily done
through the --create --alive parameters:
./elastic-mapreduce --create --aliveThe output will be similar to this:
Created job flowJobFlowID
One can verify the results in the console through the list command or through the web management console. Depending on the cluster setup and the user account, the Hadoop cluster initialization should
be complete anywhere between 1 to 5 minutes. The cluster is ready once its state changes from STARTING/PROVISIONING to WAITING.
| Note |
|---|---|
| By default, each newly created cluster has a new public IP that is not typically reused. To simplify the setup, one can use Amazon Elastic IP, that is a static, predefined IP, so that she knows before-hand the cluster address. Refer to this section inside the EMR documentation for more information. As an alternative, one can use the EC2 API in combinatioon with the EMR API to retrieve the private IP of address of the master node of her cluster or even programatically configure and start the EMR cluster on demand without having to hard-code the private IPs. |
However, to remotely access the cluster from outside (as oppose to just running a jar within the cluster), one needs to tweak the cluster settings just a tiny bit - as mentioned below.
Due to security reasons, the EMR cluster is not exposed to the outside world and is bound only to the machine internal IP. While you can open up the firewall to allow access (note that you also have to do some port forwarding since again, Hadoop is bound to the cluster internal IP rather then all available network cards), it is recommended to use a SSH tunnel instead. The SSH tunnel provides a secure connection between your machine on the cluster preventing any snooping or man-in-the-middle attacks. Further more it is quite easy to automate and be executed along side the cluster creation, programmatically or through some script. The Amazon EMR docs have dedicated sections on SSH Setup and Configuration and on opening a SSH Tunnel to the master node so please refer to them. Make sure to setup the SSH tunnel as a SOCKS proxy, that is to redirect all calls to remote ports - this is crucial when working with Hadoop (or other applications) that use a range of ports for communication.
Once the tunnel or the SOCKS proxy is in place, one needs to configure Hadoop to use it. By default, Hadoop makes connections directly to its target which is fine for regular use, but in this case, we need to
use the SOCKS proxy to pass through the firewall. One can do so through the hadoop.rpc.socket.factory.class.default and hadoop.socks.server properties:
hadoop.rpc.socket.factory.class.default=org.apache.hadoop.net.SocksSocketFactory # this configure assumes the SOCKS proxy is opened on local port 6666 hadoop.socks.server=localhost:6666
At this point, all Hadoop communication will go through the SOCKS proxy at localhost on port 6666. The main advantage is that all the IPs, domain names, ports are resolved on the 'remote' side of the proxy so
one can just start using the remote cluster IPs. However, only the Hadoop client needs to use the proxy - to avoid having the client configuration be read by the cluster nodes (which would mean the nodes would
try to use a SOCKS proxy on the remote side as well), make sure the master node (and thus all its nodes)
hadoop-site.xml marks the default network setting as final (see this blog post for a detailed
explanation):
<property> <name>hadoop.rpc.socket.factory.class.default</name> <value>org.apache.hadoop.net.StandardSocketFactory</value> <final>true</final> </property>
Simply pass this configuration (and other options that you might have) to the master node using a bootstrap action. One can find this file ready for usage, already deployed to Amazon S3 at s3://dist.springframework.org/release/SHDP/emr-settings.xml. Simply pass the file to command-line used for firing up the EMR cluster:
./elastic-mapreduce --create --alive --bootstrap-action s3://elasticmapreduce/bootstrap-actions/configure-hadoop --args "--site-config-file,s3://dist.springframework.org/release/SHDP/emr-settings.xml"
| Note |
|---|---|
| For security reasons, we recommend copying the 'emr-settings.xml' file to one of your S3 buckets and use that location instead. |
Amazon EMR offers Simple Storage Service, also known as S3 service, as means for durable read-write storage for EMR. While the cluster is active, one can write additional data to HDFS but unless S3 is used, the data will be lost once the cluster shuts down. Note that when using an S3 location for the first time, the proper access permissions needs to be setup. Accessing S3 is easier then the job tracker - in fact the Hadoop distribution provides not one but two file-system implementations for S3:
Table A.1. Hadoop S3 File Systems
| Name | URI Prefix | Access Method | Description |
|---|---|---|---|
| S3 Native FS | s3n:// | S3 Native | Native access to S3. The recommended file-system as the data is read/written in its native format and can be used not just by Hadoop but also other systems without any translation. The down-side is that it does not support large files (5GB) out of the box (though there is a work-around through the multipart upload feature). |
| S3 Block FS | s3:// | Block Based | The files are stored as blocks (similar to the underlying structure in HDFS). This is somewhat more efficient in terms of renames and file sizes but requires a dedicated bucket and is not inter-operable with other S3 tools. |
To access the data in S3 one can either use an HDFS file-system on top of it, which requires no extra setup, or copy the data from S3 to the HDFS cluster using manual tools, distcp with S3, its dedicated version s3distcp, Hadoop DistributedCache (which SHDP supports as well) or third-party tools such as s3cmd.
For newbies and development we recommend accessing the S3 directly through the File-System abstraction as in most cases, its performance is close to that of the data inside the native HDFS. When dealing with data that is read multiple times, copying the data from S3 locally inside the cluster might improve performance but we advice running some performance tests first.
Once the cluster is no longer needed for a longer period of time, one can shut it down fairly straight forward:
./elastic-mapreduce --terminate JobFlowID
Note that the EMR cluster is billed by the hour and since the time is rounded upwards, starting and shutting down the cluster repeateadly might end up being more expensive then just keeping it alive. Consult the documentation for more information.
To put it all together, to use Amazon EMR one can use the following work-flow with SHDP:
Start an alive cluster using the bootstrap action to guarantees the cluster does NOT use a socks proxy. Open a SSH tunnel, in SOCKS mode, to the EMR cluster.
Start the cluster for an indefinite period. Once the server is up, create an SSH tunnel,in SOCKS mode, to the remote cluster. This allows the client to communicate directly with the remote nodes as if they are part of the same network.This step does not have to be repeated unless the cluster is terminated - one can (and should) submit multiple jobs to it.Configure SHDP
- Once the cluster is up and the SSH tunnel/SOCKS proxy is in place, point SHDP to the new configuration. The example below shows how the configuration can look like:
hadoop-context.xml
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xmlns:hdp="http://www.springframework.org/schema/hadoop" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/hadoop http://www.springframework.org/schema/hadoop/spring-hadoop.xsd"> <!-- property placeholder backed by hadoop.properties --> <context:property-placeholder location="hadoop.properties"/> <!-- Hadoop FileSystem using a placeholder and emr.properties --> <hdp:configuration properties-location="emr.properties" file-system-uri="${hd.fs}" job-tracker-uri="${hd.jt}/>
hadoop.properties
# Amazon EMR # S3 bucket backing the HDFS S3 fs hd.fs=s3n://my-working-bucket/ # job tracker pointing to the EMR internal IP hd.jt=10.123.123.123:9000
emr.properties
# Amazon EMR # Use a SOCKS proxy hadoop.rpc.socket.factory.class.default=org.apache.hadoop.net.SocksSocketFactory hadoop.socks.server=localhost:6666 # S3 credentials # for s3:// uri fs.s3.awsAccessKeyId=XXXXXXXXXXXXXXXXXXXX fs.s3.awsSecretAccessKey=XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX # for s3n:// uri fs.s3n.awsAccessKeyId=XXXXXXXXXXXXXXXXXXXX fs.s3n.awsSecretAccessKey=XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Spring Hadoop is now ready to talk to your Amazon EMR cluster. Try it out!Note The inquisitive reader might wonder why the example above uses two properties file, hadoop.propertiesandemr.propertiesinstead of just one. While one file is enough, the example tries to isolate the EMR configuration into a separate configuration (especially as it contains security credentials). -
Shutdown the tunnel and the cluster
Once the jobs submitted are completed, unless new jobs are shortly scheduled, one can shutdown the cluster. Just like the first step, this is optional. Again, make sure you understand the billing process first.
As mentioned above, those interested in using on-demand Hadoop clusters can use Amazon Elastic Map Reduce (or Amazon EMR) service. An alternative to that, for those that want maximum control over the cluster, is to use Amazon Elastic Compute Cloud or EC2. EC2 is in fact the service on top of which Amazon EMR runs and that is, a resizable, configurable compute capacity in the cloud.
| Important |
|---|---|
| This chapter assumes the user is familiar with Amazon EC2 and the cost associated with it and its related services - we strongly recommend getting familiar with the official EC2 documentation. |
Just like Amazon EMR, using EC2 means the Hadoop cluster (or whatever service you run on it) runs in the cloud and thus 'development' access to it, is different then when running the service in local network. There are various tips and tools out there that can handle the initial provisioning and configure the access to the cluster. Such a solution is Apache Whirr which is a set of libraries for running cloud services. Though it provides a Java API as well, one can easily configure, start and stop services from the command-line.
The Whirr documentation provides more detail on how to interact with the various cloud providers out-there through Whirr.
In case of EC2, one needs Java 6 (which is required by Apache Hadoop), an account on EC2 and an SSH client (available out of the box on *nix platforms and freely downloadable (such as PuTTY) on Windows).
Since Whirr does most of the heavy lifting, one needs to tell Whirr what Cloud provider and account is used, either by setting some environment properties or through the
~/.whirr/credentials file:
whirr.provider=aws-ec2 whirr.identity=your-aws-key whirr.credential=your-aws-secret
Now instruct Whirr to configure a Hadoop cluster on EC2 - just add the following properties to a configuration file (say hadoop.properties):
whirr.cluster-name=myhadoopcluster
whirr.instance-templates=1 hadoop-jobtracker+hadoop-namenode,1 hadoop-datanode+hadoop-tasktracker
whirr.provider=aws-ec2
whirr.private-key-file=${sys:user.home}/.ssh/id_rsa
whirr.public-key-file=${sys:user.home}/.ssh/id_rsa.pub
The configuration above assumes the SSH keys for your user have been already generated. Now start your Hadoop cluster:
bin/whirr launch-cluster --config hadoop.properties
As with Amazon EMR, one cannot correct to the Hadoop cluster from outside - however Whirr provides out of the box the feature to create an SSH tunnel to create a SOCKS proxy (on port 6666).
When a cluster is created, Whirr creates a script to launch the cluster which may be found in ~/.whirr/cluster-name. Run it as a follows (in a new terminal window):
~/.whirr/myhadoopcluster/hadoop-proxy.sh
At this point, one can just the SOCKS proxy configuration from the Amazon EMR section to configure the Hadoop client.
To destroy the cluster, one can use the Amazon EMR console or Whirr itself:
bin/whirr destroy-cluster --config hadoop.properties
Spring for Apache Hadoop Schema
<?xml version="1.0" encoding="UTF-8"?> <xsd:schema xmlns="http://www.springframework.org/schema/hadoop" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:beans="http://www.springframework.org/schema/beans" xmlns:tool="http://www.springframework.org/schema/tool" targetNamespace="http://www.springframework.org/schema/hadoop" elementFormDefault="qualified" attributeFormDefault="unqualified" version="1.0.0"> <xsd:import namespace="http://www.springframework.org/schema/beans" /> <xsd:import namespace="http://www.springframework.org/schema/tool" /> <xsd:annotation> <xsd:documentation><![CDATA[ Defines the configuration elements for Spring Data Hadoop. ]]></xsd:documentation> </xsd:annotation> <!-- common attributes shared by Job executors NOT meant for extensibility - do NOT rely on this type as it might be removed in the future --> <xsd:complexType name="jobRunnerType"> <xsd:attribute name="id" type="xsd:ID" use="optional"> <xsd:annotation> <xsd:documentation><![CDATA[ Bean id.]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <!-- the job reference --> <xsd:attribute name="job-ref"> <xsd:annotation> <xsd:documentation source="java:org.apache.hadoop.mapreduce.Job"><![CDATA[ Hadoop Job. Multiple names can be specified using comma (,) as a separator.]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="org.apache.hadoop.mapreduce.Job" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="wait-for-completion" type="xsd:string" use="optional" default="true"> <xsd:annotation> <xsd:documentation><![CDATA[ Whether to synchronously wait for the job(s) to finish (the default) or not. ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="verbose" type="xsd:string" use="optional" default="true"/> <xsd:attribute name="kill-job-at-shutdown" type="xsd:string" use="optional" default="true"> <xsd:annotation> <xsd:documentation><![CDATA[ Whether the configured jobs should be 'killed' when the application shuts down (default) or not. For long-running or fire-and-forget jobs that live beyond the starting application, set this to false. Note that if 'wait-for-job' is true, this flag is considered to be true as otherwise the application cannot shut down (since it has to keep waiting for the job). ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="executor-ref" type="xsd:string" use="optional"> <xsd:annotation> <xsd:documentation source="java:java.util.concurrent.Executor"><![CDATA[ The task executor responsible for executing the task. By default SyncTaskExecutor is used, meaning the calling thread is used. While this replicates the Hadoop behavior, it prevents running jobs from being killed if the application shuts down. For fine-tuned control, a dedicated Executor is recommended. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="java:java.util.concurrent.Executor" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="scope" type="xsd:string" use="optional" /> </xsd:complexType> <xsd:element name="job-tasklet" type="jobRunnerType"> <xsd:annotation> <xsd:documentation><![CDATA[ Defines a Spring Batch tasklet for Hadoop Jobs. ]]> </xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:exports type="org.springframework.data.hadoop.mapreduce.JobTasklet"/> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:element> <xsd:element name="job-runner"> <xsd:annotation> <xsd:documentation><![CDATA[ Defines a runner for Hadoop jobs. ]]> </xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:exports type="org.springframework.data.hadoop.mapreduce.JobRunner"/> </tool:annotation> </xsd:appinfo> </xsd:annotation> <xsd:complexType> <xsd:complexContent> <xsd:extension base="jobRunnerType"> <xsd:attribute name="run-at-startup" type="xsd:string" default="false"> <xsd:annotation> <xsd:documentation><![CDATA[ Whether the Job runs at startup or not (default). ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="pre-action" type="xsd:string" default=""> <xsd:annotation> <xsd:documentation><![CDATA[ Pre actions/beans to be called before running the action. Multiple bean names can be specified using comma-separated list.]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="post-action" type="xsd:string" default=""> <xsd:annotation> <xsd:documentation><![CDATA[ Post actions/beans to be called before running the action. Multiple bean names can be specified using comma-separated list.]]></xsd:documentation> </xsd:annotation> </xsd:attribute> </xsd:extension> </xsd:complexContent> </xsd:complexType> </xsd:element> <!-- common attributes shared by properties based configurations NOT meant for extensibility - do NOT rely on this type as it might be removed in the future --> <xsd:complexType name="propertiesConfigurableType" mixed="true"> <xsd:attribute name="properties-ref" type="xsd:string"> <xsd:annotation> <xsd:documentation><![CDATA[ Reference to a Properties object. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="java.util.Properties" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="properties-location" type="xsd:string"> <xsd:annotation> <xsd:documentation><![CDATA[ Properties location(s). Multiple locations can be specified using comma (,) as a separator. ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> </xsd:complexType> <xsd:element name="configuration"> <xsd:annotation> <xsd:documentation><![CDATA[ Defines a Hadoop Configuration. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:exports type="org.apache.hadoop.conf.Configuration"/> </tool:annotation> </xsd:appinfo> </xsd:annotation> <xsd:complexType mixed="true"> <xsd:complexContent> <xsd:extension base="propertiesConfigurableType"> <xsd:attribute name="id" type="xsd:ID" use="optional"> <xsd:annotation> <xsd:documentation><![CDATA[ Bean id (default is "hadoopConfiguration"). ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="configuration-ref"> <xsd:annotation> <xsd:documentation source="java:org.apache.hadoop.conf.Configuration"><![CDATA[ Reference to another Hadoop configuration (useful for chaining)]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="org.apache.hadoop.conf.Configuration" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="resources"> <xsd:annotation> <xsd:documentation source="java:org.springframework.core.io.Resource"><![CDATA[ Hadoop Configuration resources. Multiple resources can be specified, using comma (,) as a separator.]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="direct"> <tool:expected-type type="org.springframework.core.io.Resource[]" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="register-url-handler" use="optional" default="false"> <xsd:annotation> <xsd:documentation><![CDATA[ Registers an HDFS url handler in the running VM. Note that this operation can be executed at most once in a given JVM hence the default is false. ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="depends-on" use="optional"><xsd:annotation><xsd:documentation> The names of the beans that this bean depends on being initialized. Typically used to guarantee the initialization of certain beans before the Hadoop cluster gets configured and started (directly or not through the use of its configuration and file-system). </xsd:documentation></xsd:annotation></xsd:attribute> <xsd:attribute name="file-system-uri" type="xsd:string"> <xsd:annotation> <xsd:documentation><![CDATA[ The default file-system address (host:port). Equivalent to 'fs.default.name' property.]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="job-tracker-uri" type="xsd:string"> <xsd:annotation> <xsd:documentation><![CDATA[ The Map/Reduce job tracker address (host:port). Equivalent to 'mapred.job.tracker' property.]]></xsd:documentation> </xsd:annotation> </xsd:attribute> </xsd:extension> </xsd:complexContent> </xsd:complexType> </xsd:element> <xsd:element name="file-system"> <xsd:annotation> <xsd:documentation><![CDATA[ Defines a HDFS file system. ]]> </xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:exports type="org.apache.hadoop.fs.FileSystem"/> </tool:annotation> </xsd:appinfo> </xsd:annotation> <xsd:complexType> <xsd:attribute name="id" type="xsd:ID" use="optional"> <xsd:annotation> <xsd:documentation><![CDATA[ Bean id (default is "hadoopFs"). ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="configuration-ref" use="optional" default="hadoopConfiguration"> <xsd:annotation> <xsd:documentation source="java:org.apache.hadoop.conf.Configuration"><![CDATA[ Reference to the Hadoop Configuration. Defaults to 'hadoopConfiguration'.]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="org.apache.hadoop.conf.Configuration" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="uri" use="optional"> <xsd:annotation> <xsd:documentation><![CDATA[ The underlying HDFS system URI (by default the configuration settings will be used). ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="user" type="xsd:string"> <xsd:annotation> <xsd:documentation><![CDATA[ The security user (ugi) to use for impersonation at runtime. ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="close" type="xsd:string" default="true"> <xsd:annotation> <xsd:documentation><![CDATA[ Whether or not the Hadoop file systems should be closed once this factory is destroyed. True by default - should be turned off when running 'embedded' or if long running operations outlive the application context. ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="close-all" type="xsd:string" default="false"> <xsd:annotation> <xsd:documentation><![CDATA[ Whether or not to close all file-system instances inside a JVM at shutdown or not. Useful as a leak prevention when the app drives all of Hadoop. ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="depends-on" use="optional"><xsd:annotation><xsd:documentation> The names of the beans that this bean depends on being initialized. Typically used to guarantee the initialization of certain beans before the Hadoop cluster gets configured and started (directly or not through the use of its configuration and file-system). </xsd:documentation></xsd:annotation></xsd:attribute> </xsd:complexType> </xsd:element> <xsd:element name="resource-loader"> <xsd:annotation> <xsd:documentation><![CDATA[ Defines a HDFS-aware resource loader. ]]> </xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:exports type="org.springframework.data.hadoop.fs.HdfsResourceLoader"/> </tool:annotation> </xsd:appinfo> </xsd:annotation> <xsd:complexType> <xsd:attribute name="id" type="xsd:ID" use="optional"> <xsd:annotation> <xsd:documentation><![CDATA[ Bean id (default is "hadoopResourceLoader"). ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="configuration-ref" use="optional" default="hadoopConfiguration"> <xsd:annotation> <xsd:documentation source="java:org.apache.hadoop.conf.Configuration"><![CDATA[ Reference to the Hadoop Configuration. Defaults to 'hadoopConfiguration'.]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="org.apache.hadoop.conf.Configuration" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="uri" use="optional"> <xsd:annotation> <xsd:documentation><![CDATA[ The underlying HDFS system URI (by default the configuration settings will be used). ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="file-system-ref"> <xsd:annotation> <xsd:documentation source="java:org.apache.hadoop.fs.FileSystem"><![CDATA[ Reference to the Hadoop FileSystem. Overrides the 'uri' or 'configuration-ref' properties.]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="org.apache.hadoop.fs.FileSystem" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="user" type="xsd:string"> <xsd:annotation> <xsd:documentation><![CDATA[ The security user (ugi) to use for impersonation at runtime. ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="use-codecs" type="xsd:string" use="optional" default="true"> <xsd:annotation> <xsd:documentation><![CDATA[ Indicates whether to use (or not) the codecs found inside the Hadoop configuration when accessing the resource input stream. By default, the codecs are used meaning the content of the stream backing the resource is decompressed on the fly (if a suitable decompressor is found). ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="depends-on" use="optional"><xsd:annotation><xsd:documentation> The names of the beans that this bean depends on being initialized. Typically used to guarantee the initialization of certain beans before the Hadoop cluster gets configured and started (directly or not through the use of its configuration and file-system). </xsd:documentation></xsd:annotation></xsd:attribute> </xsd:complexType> </xsd:element> <!-- generic options shared by the various jobs NOT meant for extensibility - do NOT rely on this type as it might be removed in the future --> <xsd:complexType name="genericOptionsType" mixed="true"> <xsd:complexContent> <xsd:extension base="propertiesConfigurableType"> <xsd:attribute name="archives"> <xsd:annotation> <xsd:appinfo> <xsd:documentation source="java:org.springframework.core.io.Resource"><![CDATA[ Archives to be unarchived to the cluster. Multiple resources can be specified, using comma (,) as a separator.]]></xsd:documentation> <tool:annotation kind="direct"> <tool:expected-type type="java:org.springframework.core.io.Resource[]" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="files"> <xsd:annotation> <xsd:appinfo> <xsd:documentation source="java:org.springframework.core.io.Resource"><![CDATA[ File resources to be copied to the cluster. Multiple resources can be specified, using comma (,) as a separator.]]></xsd:documentation> <tool:annotation kind="direct"> <tool:expected-type type="java:org.springframework.core.io.Resource[]" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="libs"> <xsd:annotation> <xsd:appinfo> <xsd:documentation source="java:org.springframework.core.io.Resource"><![CDATA[ Jar resources to include in the classpath. Multiple resources can be specified, using comma (,) as a separator.]]></xsd:documentation> <tool:annotation kind="direct"> <tool:expected-type type="java:org.springframework.core.io.Resource[]" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="user" type="xsd:string"> <xsd:annotation> <xsd:documentation><![CDATA[ The security user (ugi) to use for impersonation at runtime. ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> </xsd:extension> </xsd:complexContent> </xsd:complexType> <!-- common attributes shared by properties based configurations NOT meant for extensibility - do NOT rely on this type as it might be removed in the future --> <xsd:complexType name="jobType"> <xsd:complexContent> <xsd:extension base="genericOptionsType"> <xsd:attribute name="id" type="xsd:ID" use="required" /> <xsd:attribute name="scope" type="xsd:string" use="optional" /> <xsd:attribute name="mapper" default="org.apache.hadoop.mapreduce.Mapper"> <xsd:annotation> <xsd:appinfo> <tool:annotation kind="direct"> <tool:expected-type type="java.lang.Class" /> <tool:assignable-to type="org.apache.hadoop.mapreduce.Mapper" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="reducer" default="org.apache.hadoop.mapreduce.Reducer"> <xsd:annotation> <xsd:appinfo> <tool:annotation kind="direct"> <tool:expected-type type="java.lang.Class" /> <tool:assignable-to type="org.apache.hadoop.mapreduce.Reducer" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="combiner"> <xsd:annotation> <xsd:documentation><![CDATA[ The combiner class name. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="direct"> <tool:expected-type type="java.lang.Class" /> <tool:assignable-to type="org.apache.hadoop.mapreduce.Reducer" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="input-format"> <xsd:annotation> <xsd:appinfo> <tool:annotation kind="direct"> <tool:expected-type type="java.lang.Class" /> <tool:assignable-to type="org.apache.hadoop.mapreduce.InputFormat" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="output-format"> <xsd:annotation> <xsd:appinfo> <tool:annotation kind="direct"> <tool:expected-type type="java.lang.Class" /> <tool:assignable-to type="org.apache.hadoop.mapreduce.OutputFormat" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="partitioner"> <xsd:annotation> <xsd:appinfo> <tool:annotation kind="direct"> <tool:expected-type type="java.lang.Class" /> <tool:assignable-to type="org.apache.hadoop.mapreduce.Partitioner" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="input-path" use="optional"> <xsd:annotation> <xsd:appinfo> <tool:annotation kind="direct"> <tool:expected-type type="java.lang.String[]" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="output-path" use="optional"> <xsd:annotation> <xsd:appinfo> <tool:annotation kind="direct"> <tool:expected-type type="java.lang.String" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="number-reducers"> <xsd:annotation> <xsd:appinfo> <tool:annotation kind="direct"> <tool:expected-type type="java.lang.Integer" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="configuration-ref" default="hadoopConfiguration"> <xsd:annotation> <xsd:documentation source="java:org.apache.hadoop.conf.Configuration"><![CDATA[ Reference to the Hadoop Configuration. Defaults to 'hadoopConfiguration'.]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="org.apache.hadoop.conf.Configuration" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> </xsd:extension> </xsd:complexContent> </xsd:complexType> <xsd:element name="job"> <xsd:annotation> <xsd:documentation><![CDATA[ Defines a Hadoop Job. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:exports type="org.apache.hadoop.mapreduce.Job"/> </tool:annotation> </xsd:appinfo> </xsd:annotation> <xsd:complexType> <xsd:complexContent mixed="true"> <xsd:extension base="jobType"> <xsd:attribute name="sort-comparator"> <xsd:annotation> <xsd:appinfo> <tool:annotation kind="direct"> <tool:expected-type type="java.lang.Class" /> <tool:assignable-to type="org.apache.hadoop.io.RawComparator" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="grouping-comparator"> <xsd:annotation> <xsd:appinfo> <tool:annotation kind="direct"> <tool:expected-type type="java.lang.Class" /> <tool:assignable-to type="org.apache.hadoop.io.RawComparator" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="key"> <xsd:annotation> <xsd:appinfo> <tool:annotation kind="direct"> <tool:expected-type type="java.lang.Class" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="value"> <xsd:annotation> <xsd:appinfo> <tool:annotation kind="direct"> <tool:expected-type type="java.lang.Class" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="map-key"> <xsd:annotation> <xsd:appinfo> <tool:annotation kind="direct"> <tool:expected-type type="java.lang.Class" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="map-value"> <xsd:annotation> <xsd:appinfo> <tool:annotation kind="direct"> <tool:expected-type type="java.lang.Class" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="codec"> <xsd:annotation> <xsd:appinfo> <tool:annotation kind="direct"> <tool:expected-type type="java.lang.Class" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="jar"> <xsd:annotation> <xsd:documentation><![CDATA[ Indicates the user jar for the map-reduce job. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:expected-type type="org.springframework.core.io.Resource" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="jar-by-class"> <xsd:annotation> <xsd:documentation><![CDATA[ Indicates the job's jar file by finding an example class location. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="direct"> <tool:expected-type type="java.lang.Class" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="working-dir"> <xsd:annotation> <xsd:documentation><![CDATA[ Indicates the job's working directory. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="direct"> <tool:expected-type type="java.lang.String" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="compress-output"> <xsd:annotation> <xsd:documentation><![CDATA[ Indicates whether the job output should be compressed or not. By default it is not set. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="direct"> <tool:expected-type type="java.lang.Boolean" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> </xsd:extension> </xsd:complexContent> </xsd:complexType> </xsd:element> <xsd:element name="streaming"> <xsd:annotation> <xsd:documentation><![CDATA[ Defines a Hadoop Streaming Job. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:exports type="org.apache.hadoop.mapreduce.Job"/> </tool:annotation> </xsd:appinfo> </xsd:annotation> <xsd:complexType> <xsd:complexContent mixed="true"> <xsd:extension base="jobType"> <xsd:sequence> <xsd:element name="cmd-env" minOccurs="0" maxOccurs="1"> <xsd:annotation> <xsd:documentation><![CDATA[Environment variables (-cmdenv)]]></xsd:documentation> </xsd:annotation> </xsd:element> </xsd:sequence> </xsd:extension> </xsd:complexContent> </xsd:complexType> </xsd:element> <!-- common attributes shared by properties based configurations NOT meant for extensibility - do NOT rely on this type as it might be removed in the future --> <xsd:complexType name="hadoopRunnerType"> <xsd:complexContent mixed="true"> <xsd:extension base="genericOptionsType"> <xsd:sequence> <xsd:element name="arg" minOccurs="0" maxOccurs="unbounded"> <xsd:annotation> <xsd:documentation><![CDATA[ Tool argument.]]></xsd:documentation> </xsd:annotation> <xsd:complexType> <xsd:attribute name="value" type="xsd:string" use="required"/> </xsd:complexType> </xsd:element> </xsd:sequence> <xsd:attribute name="id" type="xsd:ID" use="optional"> <xsd:annotation> <xsd:documentation><![CDATA[ Bean id.]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="configuration-ref" default="hadoopConfiguration"> <xsd:annotation> <xsd:documentation source="java:org.apache.hadoop.conf.Configuration"><![CDATA[ Reference to the Hadoop Configuration. Defaults to 'hadoopConfiguration'.]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="org.apache.hadoop.conf.Configuration" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> </xsd:extension> </xsd:complexContent> </xsd:complexType> <!-- common attributes shared by properties based configurations NOT meant for extensibility - do NOT rely on this type as it might be removed in the future --> <xsd:complexType name="jarRunnerType"> <xsd:complexContent mixed="true"> <xsd:extension base="hadoopRunnerType"> <xsd:attribute name="jar" type="xsd:string" use="required"> <xsd:annotation> <xsd:documentation><![CDATA[ Indicates the jar (not required to be in the classpath). ]]></xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:expected-type type="org.springframework.core.io.Resource" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="main-class" type="xsd:string"> <xsd:annotation> <xsd:documentation><![CDATA[ Indicates the Jar entry/main class name. If not specified, the Main-Class (specified in the MANIFEST.MF), if present, is used instead. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="direct"> <tool:expected-type type="java.lang.Class" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="close-fs" type="xsd:string" default="true"> <xsd:annotation> <xsd:documentation><![CDATA[ Wherther to close or not, any file-systems created by the Jar execution. Default is true. Turn this off, if the jar uses the same file-system as the rest of the application. ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="scope" type="xsd:string" use="optional" /> </xsd:extension> </xsd:complexContent> </xsd:complexType> <xsd:element name="jar-runner"> <xsd:annotation> <xsd:documentation><![CDATA[ Executes a Hadoop Jar.]]></xsd:documentation> </xsd:annotation> <xsd:complexType> <xsd:complexContent mixed="true"> <xsd:extension base="jarRunnerType"> <xsd:attribute name="run-at-startup" type="xsd:string" default="false"> <xsd:annotation> <xsd:documentation><![CDATA[ Whether the Jar runs at startup or not (default). ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="pre-action" type="xsd:string" default=""> <xsd:annotation> <xsd:documentation><![CDATA[ Pre actions/beans to be called before running the action. Multiple bean names can be specified using comma-separated list.]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="post-action" type="xsd:string" default=""> <xsd:annotation> <xsd:documentation><![CDATA[ Post actions/beans to be called before running the action. Multiple bean names can be specified using comma-separated list.]]></xsd:documentation> </xsd:annotation> </xsd:attribute> </xsd:extension> </xsd:complexContent> </xsd:complexType> </xsd:element> <xsd:element name="jar-tasklet" type="jarRunnerType"> <xsd:annotation> <xsd:documentation><![CDATA[ Defines a Hadoop Jar Tasklet.]]></xsd:documentation> </xsd:annotation> </xsd:element> <!-- common attributes shared by properties based configurations NOT meant for extensibility - do NOT rely on this type as it might be removed in the future --> <xsd:complexType name="toolRunnerType"> <xsd:complexContent mixed="true"> <xsd:extension base="hadoopRunnerType"> <xsd:sequence> <xsd:element name="tool" minOccurs="0" maxOccurs="1"> <xsd:complexType> <xsd:sequence> <xsd:any namespace="##any" processContents="lax" minOccurs="1" maxOccurs="1"/> </xsd:sequence> </xsd:complexType> </xsd:element> </xsd:sequence> <xsd:attribute name="jar" type="xsd:string" use="optional"> <xsd:annotation> <xsd:documentation><![CDATA[ Indicates the jar (not required to be in the classpath) providing the Tool (and its dependencies). ]]></xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:expected-type type="org.springframework.core.io.Resource" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="tool-class" type="xsd:string"> <xsd:annotation> <xsd:documentation><![CDATA[ Indicates the Tool class name. This is useful when referring to an external jar (not required in the classpath). If not specified, the Main-Class (specified in the MANIFEST.MF), if present, is used instead. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="direct"> <tool:expected-type type="java.lang.Class" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="tool-ref"> <xsd:annotation> <xsd:documentation source="java:org.apache.hadoop.util.Tool"><![CDATA[ Reference to a Hadoop Tool instance.]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="org.apache.hadoop.util.Tool" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="close-fs" type="xsd:string" default="true"> <xsd:annotation> <xsd:documentation><![CDATA[ Wherther to close or not, any file-systems created by the Tool execution. Default is true. Turn this off, if the jar uses the same file-system as the rest of the application. ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="scope" type="xsd:string" use="optional" /> </xsd:extension> </xsd:complexContent> </xsd:complexType> <xsd:element name="tool-runner"> <xsd:annotation> <xsd:documentation><![CDATA[ Executes a Hadoop Tool.]]></xsd:documentation> </xsd:annotation> <xsd:complexType> <xsd:complexContent mixed="true"> <xsd:extension base="toolRunnerType"> <xsd:attribute name="run-at-startup" type="xsd:string" default="false"> <xsd:annotation> <xsd:documentation><![CDATA[ Whether the Tool runs at startup or not (default). ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="pre-action" type="xsd:string" default=""> <xsd:annotation> <xsd:documentation><![CDATA[ Pre actions/beans to be called before running the action. Multiple bean names can be specified using comma-separated list.]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="post-action" type="xsd:string" default=""> <xsd:annotation> <xsd:documentation><![CDATA[ Post actions/beans to be called before running the action. Multiple bean names can be specified using comma-separated list.]]></xsd:documentation> </xsd:annotation> </xsd:attribute> </xsd:extension> </xsd:complexContent> </xsd:complexType> </xsd:element> <xsd:element name="tool-tasklet" type="toolRunnerType"> <xsd:annotation> <xsd:documentation><![CDATA[ Defines a Hadoop Tool Tasklet.]]></xsd:documentation> </xsd:annotation> </xsd:element> <xsd:complexType name="entryType"> <xsd:attribute name="value" type="xsd:string" use="required"/> </xsd:complexType> <xsd:element name="cache"> <xsd:annotation> <xsd:documentation><![CDATA[ Configures Hadoop Distributed Cache. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:exports type="org.apache.hadoop.io.DistributedCacheFactoryBean"/> </tool:annotation> </xsd:appinfo> </xsd:annotation> <xsd:complexType> <xsd:sequence minOccurs="1" maxOccurs="unbounded"> <xsd:choice> <xsd:element name="classpath" type="entryType"/> <xsd:element name="cache" type="entryType"/> <xsd:element name="local" type="entryType"/> </xsd:choice> </xsd:sequence> <xsd:attribute name="id" type="xsd:ID" use="optional"> <xsd:annotation> <xsd:documentation><![CDATA[ Bean id (default is "hadoopCache"). ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="create-symlink" type="xsd:string" default="false"/> <xsd:attribute name="configuration-ref" default="hadoopConfiguration"> <xsd:annotation> <xsd:documentation source="java:org.apache.hadoop.conf.Configuration"><![CDATA[ Reference to the Hadoop Configuration. Defaults to 'hadoopConfiguration'.]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="org.apache.hadoop.conf.Configuration" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="file-system-ref"> <xsd:annotation> <xsd:documentation source="java:org.apache.hadoop.fs.FileSystem"><![CDATA[ Reference to the Hadoop FileSystem.]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="org.apache.hadoop.fs.FileSystem" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> </xsd:complexType> </xsd:element> <xsd:complexType name="scriptType" mixed="true"> <xsd:attribute name="location" type="xsd:string"> <xsd:annotation> <xsd:documentation><![CDATA[ Location of the script. As an alternative one can inline the script by using a nested, text declaration.]]></xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:expected-type type="org.springframework.core.io.Resource"/> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> </xsd:complexType> <xsd:complexType name="scriptWithArgumentsType" mixed="true"> <xsd:complexContent> <xsd:extension base="scriptType"> <xsd:sequence> <xsd:element name="arguments" minOccurs="0" maxOccurs="1"> <xsd:annotation> <xsd:documentation><![CDATA[ Argument(s) to pass to this script. Defined in Properties format (key=value). ]]></xsd:documentation> </xsd:annotation> </xsd:element> </xsd:sequence> </xsd:extension> </xsd:complexContent> </xsd:complexType> <xsd:element name="pig-factory"> <xsd:annotation> <xsd:documentation><![CDATA[ Defines a Pig (Server) factory. The factory is thread-safe and allows creation of PigServer instances (which are not thread-safe). ]]> </xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:exports type="org.springframework.data.hadoop.pig.PigServerFactory"/> </tool:annotation> </xsd:appinfo> </xsd:annotation> <xsd:complexType> <xsd:complexContent mixed="true"> <xsd:extension base="propertiesConfigurableType"> <xsd:sequence> <xsd:element name="script" type="scriptWithArgumentsType" minOccurs="0" maxOccurs="unbounded"> <xsd:annotation> <xsd:documentation><![CDATA[ Pig script.]]></xsd:documentation> </xsd:annotation> </xsd:element> </xsd:sequence> <xsd:attribute name="id" type="xsd:ID" use="optional"> <xsd:annotation> <xsd:documentation><![CDATA[ Bean id (default is "pigFactory"). ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="paths-to-skip"> <xsd:annotation> <xsd:documentation><![CDATA[ The path to be skipped while automatically shipping binaries for streaming. Multiple resources can be specified, using comma (,) as a separator. ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="parallelism" type="xsd:integer"/> <xsd:attribute name="validate-each-statement" type="xsd:string"/> <xsd:attribute name="job-priority" type="xsd:string"/> <xsd:attribute name="job-name" type="xsd:string"/> <xsd:attribute name="job-tracker" type="xsd:string"/> <xsd:attribute name="configuration-ref" default="hadoopConfiguration"> <xsd:annotation> <xsd:documentation source="java:org.apache.hadoop.conf.Configuration"><![CDATA[ Reference to the Hadoop Configuration. Defaults to 'hadoopConfiguration'. Can be tweaked through the 'configuration' element or the other attributes.]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="org.apache.hadoop.conf.Configuration" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="exec-type" default="MAPREDUCE"> <xsd:simpleType> <xsd:restriction base="xsd:string"> <xsd:enumeration value="MAPREDUCE"/> <xsd:enumeration value="LOCAL"/> </xsd:restriction> </xsd:simpleType> </xsd:attribute> <xsd:attribute name="user" type="xsd:string"> <xsd:annotation> <xsd:documentation><![CDATA[ The security user (ugi) to use for impersonation at runtime. ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> </xsd:extension> </xsd:complexContent> </xsd:complexType> </xsd:element> <!-- common attributes shared by Pig executors NOT meant for extensibility - do NOT rely on this type as it might be removed in the future --> <xsd:complexType name="pigRunnerType"> <xsd:sequence> <xsd:element name="script" type="scriptWithArgumentsType" minOccurs="0" maxOccurs="unbounded"> <xsd:annotation> <xsd:documentation><![CDATA[ Pig script.]]></xsd:documentation> </xsd:annotation> </xsd:element> </xsd:sequence> <xsd:attribute name="id" type="xsd:ID" use="optional"> <xsd:annotation> <xsd:documentation><![CDATA[ Bean id.]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="pig-factory-ref" type="xsd:string" use="optional" default="pigFactory"> <xsd:annotation> <xsd:documentation source="java:org.springframework.data.hadoop.pig.PigServerFactory"><![CDATA[ Reference to a PigServer factory. Defaults to 'pigFactory'. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="org.springframework.data.hadoop.pig.PigServerFactory" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="pig-template-ref" type="xsd:string" use="optional"> <xsd:annotation> <xsd:documentation source="java:org.springframework.data.hadoop.pig.PigTemplate"><![CDATA[ Reference to a PigTemplate. Alternative to 'pig-server-ref' attribute. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="org.springframework.data.hadoop.pig.PigTemplate" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="scope" type="xsd:string" use="optional" /> </xsd:complexType> <xsd:element name="pig-tasklet" type="pigRunnerType"> <xsd:annotation> <xsd:documentation><![CDATA[ Defines a PigTasklet. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:exports type="org.springframework.data.hadoop.pig.PigTasket"/> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:element> <xsd:element name="pig-runner"> <xsd:annotation> <xsd:documentation><![CDATA[ Runs Pig scripts. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:exports type="org.springframework.data.hadoop.pig.PigRunner"/> </tool:annotation> </xsd:appinfo> </xsd:annotation> <xsd:complexType> <xsd:complexContent> <xsd:extension base="pigRunnerType"> <xsd:attribute name="run-at-startup" type="xsd:string" default="false"> <xsd:annotation> <xsd:documentation><![CDATA[ Whether the Pig script runs at startup or not (default). ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="pre-action" type="xsd:string" default=""> <xsd:annotation> <xsd:documentation><![CDATA[ Pre actions/beans to be called before running the action. Multiple bean names can be specified using comma-separated list.]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="post-action" type="xsd:string" default=""> <xsd:annotation> <xsd:documentation><![CDATA[ Post actions/beans to be called before running the action. Multiple bean names can be specified using comma-separated list.]]></xsd:documentation> </xsd:annotation> </xsd:attribute> </xsd:extension> </xsd:complexContent> </xsd:complexType> </xsd:element> <xsd:element name="pig-template"> <xsd:annotation> <xsd:documentation><![CDATA[ Creates a PigTemplate. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:exports type="org.springframework.data.hadoop.pig.PigTemplate"/> </tool:annotation> </xsd:appinfo> </xsd:annotation> <xsd:complexType> <xsd:attribute name="id" type="xsd:ID" use="optional"> <xsd:annotation> <xsd:documentation><![CDATA[ Bean id (default is "pigTemplate"). ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="pig-factory-ref" type="xsd:string" use="optional" default="pigFactory"> <xsd:annotation> <xsd:documentation source="java:org.springframework.data.hadoop.pig.PigServerFactory"><![CDATA[ Reference to a PigServer factory. Defaults to 'pigFactory'. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="org.springframework.data.hadoop.pig.PigServerFactory" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> </xsd:complexType> </xsd:element> <!-- HBase --> <xsd:element name="hbase-configuration"> <xsd:complexType> <xsd:complexContent mixed="true"> <xsd:extension base="propertiesConfigurableType"> <xsd:annotation> <xsd:documentation><![CDATA[ Defines an HBase configuration. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:exports type="org.apache.hadoop.conf.Configuration"/> </tool:annotation> </xsd:appinfo> </xsd:annotation> <xsd:attribute name="id" type="xsd:ID" use="optional"> <xsd:annotation> <xsd:documentation><![CDATA[ Bean id (default is "hbaseConfiguration"). ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="zk-quorum" type="xsd:string"> <xsd:annotation> <xsd:documentation><![CDATA[ HBase Zookeeper Quorum host(s). If not specified, the default value (picked the the classpath) is used.]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="org.apache.hadoop.conf.Configuration" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="zk-port" type="xsd:string"> <xsd:annotation> <xsd:documentation source="java:org.apache.hadoop.conf.Configuration"><![CDATA[ HBase Zookeeper port for clients to connect to. If not specified, the default value (picked from the classpath) is used.]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="org.apache.hadoop.conf.Configuration" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="stop-proxy" type="xsd:string" default="true"/> <xsd:attribute name="delete-connection" type="xsd:string" default="true"/> <xsd:attribute name="configuration-ref" default="hadoopConfiguration"> <xsd:annotation> <xsd:documentation source="java:org.apache.hadoop.conf.Configuration"><![CDATA[ Reference to the Hadoop configuration. Defaults to 'hadoopConfiguration'.]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="org.apache.hadoop.conf.Configuration" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> </xsd:extension> </xsd:complexContent> </xsd:complexType> </xsd:element> <!-- Hive --> <xsd:element name="hive-client-factory"> <xsd:complexType> <xsd:annotation> <xsd:documentation><![CDATA[ Defines a HiveClient factory for connecting to a Hive server through the Thrift protocol. The factory is thread-safe and allows creation of HiveClient instances (which are not thread-safe). ]]></xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:exports type="org.springframework.data.hadoop.hive.HiveClientFactory"/> </tool:annotation> </xsd:appinfo> </xsd:annotation> <xsd:sequence> <xsd:element name="script" type="scriptWithArgumentsType" minOccurs="0" maxOccurs="unbounded"> <xsd:annotation> <xsd:documentation><![CDATA[ Hive script to be executed during start-up.]]></xsd:documentation> </xsd:annotation> </xsd:element> </xsd:sequence> <xsd:attribute name="id" type="xsd:ID" use="optional"> <xsd:annotation> <xsd:documentation><![CDATA[ Bean id (default is "hiveClientFactory"). ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="host" type="xsd:string" default="localhost"/> <xsd:attribute name="port" type="xsd:string" default="10000"/> </xsd:complexType> </xsd:element> <xsd:element name="hive-server"> <xsd:complexType> <xsd:complexContent mixed="true"> <xsd:extension base="propertiesConfigurableType"> <xsd:annotation> <xsd:documentation><![CDATA[ Defines an embedded Hive Server instance opened for access through the Thrift protocol. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:exports type="org.apache.thrift.server.TServer"/> </tool:annotation> </xsd:appinfo> </xsd:annotation> <xsd:attribute name="id" type="xsd:ID" use="optional"> <xsd:annotation> <xsd:documentation><![CDATA[ Bean id (default is "hiveServer"). ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="port" type="xsd:string" default="10000"/> <xsd:attribute name="min-threads" type="xsd:string" default="5"/> <xsd:attribute name="max-threads" type="xsd:string" default="100"/> <xsd:attribute name="auto-startup" type="xsd:string" default="true"/> <xsd:attribute name="configuration-ref" default="hadoopConfiguration"> <xsd:annotation> <xsd:documentation source="java:org.apache.hadoop.conf.Configuration"><![CDATA[ Reference to the Hadoop configuration. Defaults to 'hadoopConfiguration'.]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="org.apache.hadoop.conf.Configuration" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> </xsd:extension> </xsd:complexContent> </xsd:complexType> </xsd:element> <xsd:complexType name="hiveRunnerType"> <xsd:sequence> <xsd:element name="script" type="scriptWithArgumentsType" minOccurs="0" maxOccurs="unbounded"> <xsd:annotation> <xsd:documentation><![CDATA[ Hive script.]]></xsd:documentation> </xsd:annotation> </xsd:element> </xsd:sequence> <xsd:attribute name="id" type="xsd:ID" use="optional"> <xsd:annotation> <xsd:documentation><![CDATA[ Bean id.]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="hive-client-factory-ref" type="xsd:string" use="optional" default="hiveClientFactory"> <xsd:annotation> <xsd:documentation source="java:org.springframework.data.hadoop.hive.HiveClientFactory"><![CDATA[ Reference to a HiveClient factory instance. Defaults to 'hiveClientFactory'. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="org.springframework.data.hadoop.hive.HiveClientFactory" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="hive-template-ref" type="xsd:string" use="optional"> <xsd:annotation> <xsd:documentation source="java:org.springframework.data.hadoop.hive.HiveTemplate"><![CDATA[ Reference to a HiveTemplate instance. Alternative to 'hive-client-factory-ref' attribute.. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="org.springframework.data.hadoop.hive.HiveTemplate" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="scope" type="xsd:string" use="optional" /> </xsd:complexType> <xsd:element name="hive-tasklet" type="hiveRunnerType"> <xsd:annotation> <xsd:documentation><![CDATA[ Defines a HiveTasklet. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:exports type="org.springframework.data.hadoop.hive.HiveTasket"/> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:element> <xsd:element name="hive-runner"> <xsd:annotation> <xsd:documentation><![CDATA[ Runs Hive scripts. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:exports type="org.springframework.data.hadoop.hive.HiveRunner"/> </tool:annotation> </xsd:appinfo> </xsd:annotation> <xsd:complexType> <xsd:complexContent> <xsd:extension base="hiveRunnerType"> <xsd:attribute name="run-at-startup" type="xsd:string" default="false"> <xsd:annotation> <xsd:documentation><![CDATA[ Whether the Hive script runs at startup or not (default). ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="pre-action" type="xsd:string" default=""> <xsd:annotation> <xsd:documentation><![CDATA[ Pre actions/beans to be called before running the action. Multiple bean names can be specified using comma-separated list.]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="post-action" type="xsd:string" default=""> <xsd:annotation> <xsd:documentation><![CDATA[ Post actions/beans to be called before running the action. Multiple bean names can be specified using comma-separated list.]]></xsd:documentation> </xsd:annotation> </xsd:attribute> </xsd:extension> </xsd:complexContent> </xsd:complexType> </xsd:element> <xsd:element name="hive-template"> <xsd:annotation> <xsd:documentation><![CDATA[ Creates a HiveTemplate. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:exports type="org.springframework.data.hadoop.hive.HiveTemplate"/> </tool:annotation> </xsd:appinfo> </xsd:annotation> <xsd:complexType> <xsd:attribute name="id" type="xsd:ID" use="optional"> <xsd:annotation> <xsd:documentation><![CDATA[ Bean id (default is "hiveTemplate"). ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="hive-client-factory-ref" default="hiveClientFactory"> <xsd:annotation> <xsd:documentation source="java:org.springframework.data.hadoop.hive.HiveClientFactory"><![CDATA[ Reference to HiveClient factory. Defaults to 'hiveClientFactory'.]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="org.springframework.data.hadoop.hive.HiveClientFactory" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> </xsd:complexType> </xsd:element> <!-- Script type - NOT mean to be reused outside this schema --> <xsd:complexType name="scriptingType" abstract="true" mixed="true"> <xsd:sequence> <xsd:element name="property" type="beans:propertyType" minOccurs="0" maxOccurs="unbounded"> <xsd:annotation> <xsd:documentation><![CDATA[ Property to pass to the script. Can be used to enhance or override the default properties. ]]></xsd:documentation> </xsd:annotation> </xsd:element> </xsd:sequence> <xsd:attribute name="location" type="xsd:string"> <xsd:annotation> <xsd:documentation><![CDATA[ The location of the script. Can be any resource on the local filesystem, web or even hdfs. ]]> </xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="language" type="xsd:string"> <xsd:annotation> <xsd:documentation><![CDATA[ The language used for executing the script. If no value is given, the script source extension is used to determine the scripting engine. ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="evaluate" default="ALWAYS"> <xsd:annotation> <xsd:documentation><![CDATA[ When to evaluate the script. 'ALWAYS' (default) evaluates the script on all invocations, 'IF_MODIFIED' if the script source has been modified since the last invocation and 'ONCE' only once for the duration of the application. ]]></xsd:documentation> </xsd:annotation> <xsd:simpleType> <xsd:restriction base="xsd:string"> <xsd:enumeration value="ONCE"/> <xsd:enumeration value="IF_MODIFIED"/> <xsd:enumeration value="ALWAYS"/> </xsd:restriction> </xsd:simpleType> </xsd:attribute> </xsd:complexType> <xsd:element name="script"> <xsd:complexType mixed="true"> <xsd:complexContent> <xsd:annotation> <xsd:documentation><![CDATA[ Dedicated scripting facility for interacting with Hadoop. Allows Groovy, JavaScript (Rhino), Ruby (JRuby), Python (Jython) or any JSR-223 scripting language to be used for executing commands against Hadoop, in particular its file system. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:exports type="java.lang.Object"/> </tool:annotation> </xsd:appinfo> </xsd:annotation> <xsd:extension base="scriptingType"> <xsd:attribute name="id" type="xsd:ID" use="optional"> <xsd:annotation> <xsd:documentation><![CDATA[ Bean id (if no value is given, a name will be generated). ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="run-at-startup" type="xsd:string" default="false"> <xsd:annotation> <xsd:documentation><![CDATA[ Whether the script is evaluated automatically once the application context initializes or only when in use (the default). ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="scope" type="xsd:string" use="optional" /> <xsd:attribute name="configuration-ref" default="hadoopConfiguration"> <xsd:annotation> <xsd:documentation source="java:org.apache.hadoop.conf.Configuration"><![CDATA[ Reference to the Hadoop Configuration. Defaults to 'hadoopConfiguration'.]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="org.apache.hadoop.conf.Configuration" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="pre-action" type="xsd:string" default=""> <xsd:annotation> <xsd:documentation><![CDATA[ Pre actions/beans to be called before running the action. Multiple bean names can be specified using comma-separated list.]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="post-action" type="xsd:string" default=""> <xsd:annotation> <xsd:documentation><![CDATA[ Post actions/beans to be called before running the action. Multiple bean names can be specified using comma-separated list.]]></xsd:documentation> </xsd:annotation> </xsd:attribute> </xsd:extension> </xsd:complexContent> </xsd:complexType> </xsd:element> <xsd:element name="script-tasklet"> <xsd:complexType> <xsd:annotation> <xsd:documentation><![CDATA[ Defines a scripting Tasklet for interacting with Hadoop. Allows Groovy, JavaScript (Rhino), Ruby (JRuby), Python (Jython) or any JSR-223 scripting language to be used for executing commands against Hadoop, in particular its file system. ]]> </xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:exports type="java.lang.Object"/> </tool:annotation> </xsd:appinfo> </xsd:annotation> <xsd:sequence> <xsd:element name="script" minOccurs="0" maxOccurs="1"> <xsd:annotation> <xsd:documentation><![CDATA[ Nested script declaration.]]></xsd:documentation> </xsd:annotation> <xsd:complexType mixed="true"> <xsd:complexContent> <xsd:extension base="scriptingType"/> </xsd:complexContent> </xsd:complexType> </xsd:element> </xsd:sequence> <xsd:attribute name="id" type="xsd:ID" use="optional"> <xsd:annotation> <xsd:documentation><![CDATA[ Bean id.]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="script-ref" type="xsd:string"> <xsd:annotation> <xsd:documentation><![CDATA[ Reference to a script declaration.]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="java.lang.Object" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="scope" type="xsd:string" use="optional" /> </xsd:complexType> </xsd:element> <!-- Cascading --> <xsd:complexType name="cascadingRunnerType"> <xsd:attribute name="id" type="xsd:ID" use="optional"> <xsd:annotation> <xsd:documentation><![CDATA[ Bean id.]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="unit-of-work-ref" type="xsd:string" use="required"> <xsd:annotation> <xsd:documentation source="java:cascading.manangement.UnitOfWork"><![CDATA[ Reference to a Cascading UnitOfWork (or uow) - that is a Cascade or sometimes a Flow. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="cascading.manangement.UnitOfWork" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="wait-for-completion" type="xsd:string" use="optional" default="true"> <xsd:annotation> <xsd:documentation><![CDATA[ Whether to synchronously wait for the unit of work to finish (the default) or not. ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="scope" type="xsd:string" use="optional" /> </xsd:complexType> <xsd:element name="cascading-tasklet" type="cascadingRunnerType"> <xsd:annotation> <xsd:documentation><![CDATA[ Defines a Spring Batch tasklet for Cascading. ]]> </xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:exports type="org.springframework.data.hadoop.cascading.CascadingTasklet"/> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:element> <xsd:element name="cascading-runner"> <xsd:annotation> <xsd:documentation><![CDATA[ Defines a runner for Cascading unit of work (typically Cascades). ]]> </xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:exports type="org.springframework.data.hadoop.cascading.CascadingRunner"/> </tool:annotation> </xsd:appinfo> </xsd:annotation> <xsd:complexType> <xsd:complexContent> <xsd:extension base="cascadingRunnerType"> <xsd:attribute name="run-at-startup" type="xsd:string" default="false"> <xsd:annotation> <xsd:documentation><![CDATA[ Whether the Cascade runs at startup or not (default). ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="pre-action" type="xsd:string" default=""> <xsd:annotation> <xsd:documentation><![CDATA[ Pre actions/beans to be called before running the action. Multiple bean names can be specified using comma-separated list.]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="post-action" type="xsd:string" default=""> <xsd:annotation> <xsd:documentation><![CDATA[ Post actions/beans to be called before running the action. Multiple bean names can be specified using comma-separated list.]]></xsd:documentation> </xsd:annotation> </xsd:attribute> </xsd:extension> </xsd:complexContent> </xsd:complexType> </xsd:element> <xsd:element name="cascading-cascade"> <xsd:annotation> <xsd:documentation><![CDATA[ Defines a Cascading Cascade (an assembly of Flows). ]]></xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:exports type="org.springframework.data.hadoop.cascading.CascadeFactoryBean"/> </tool:annotation> </xsd:appinfo> </xsd:annotation> <xsd:complexType> <xsd:complexContent mixed="true"> <xsd:extension base="propertiesConfigurableType"> <xsd:attribute name="id" type="xsd:ID" use="required"> <xsd:annotation> <xsd:documentation><![CDATA[ Bean id. ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="definition-ref" type="xsd:string" use="optional"> <xsd:annotation> <xsd:documentation source="java:cascading.cascade.CascadeDef"><![CDATA[ Reference to a Cascade definition. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="cascading.cascade.CascadeDef" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="flow-ref" type="xsd:string" use="optional"> <xsd:annotation> <xsd:documentation source="java:cascading.flow.Flow"><![CDATA[ Reference to a Cascading Flow. Multiple names can be specified using comma (,) as a separator. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="cascading.flow.Flow" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="configuration-ref" default="hadoopConfiguration"> <xsd:annotation> <xsd:documentation source="java:org.apache.hadoop.conf.Configuration"><![CDATA[ Reference to the Hadoop configuration. Defaults to 'hadoopConfiguration'.]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="org.apache.hadoop.conf.Configuration" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> </xsd:extension> </xsd:complexContent> </xsd:complexType> </xsd:element> <xsd:element name="cascading-flow"> <xsd:annotation> <xsd:documentation><![CDATA[ Defines a Cascading Hadoop Flow using a FlowDef. For declarative configuration of Sinks and Taps consider using the HadoopFlowFactoryBean directly. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:exports type="org.springframework.data.hadoop.cascading.HadoopFlowFactoryBean"/> </tool:annotation> </xsd:appinfo> </xsd:annotation> <xsd:complexType> <xsd:complexContent mixed="true"> <xsd:extension base="propertiesConfigurableType"> <xsd:attribute name="id" type="xsd:ID" use="required"> <xsd:annotation> <xsd:documentation><![CDATA[ Bean id. ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="definition-ref" type="xsd:string" use="required"> <xsd:annotation> <xsd:documentation source="java:cascading.flow.FlowDef"><![CDATA[ Reference to a Flow definition. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="cascading.flow.FlowDef" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="add-cascading-jars" type="xsd:string" use="optional" default="true"> <xsd:annotation> <xsd:documentation><![CDATA[ Indicates whether the Cascading library jars should be added to the flow classpath (through the DistributedCache). By default it is true. When running against a cluster where Cascading jars are already installed, turn this to false to avoid shipping the library jars with the job. ]]></xsd:documentation> </xsd:annotation> </xsd:attribute> <xsd:attribute name="jar" type="xsd:string" use="optional"> <xsd:annotation> <xsd:documentation><![CDATA[ Indicates the user jar (which can be outside the classpath) for this Flow. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation> <tool:expected-type type="org.springframework.core.io.Resource" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="jar-by-class" type="xsd:string" use="optional"> <xsd:annotation> <xsd:documentation><![CDATA[ Indicates the job's jar file by finding an example class location. ]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="direct"> <tool:expected-type type="java.lang.Class" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> <xsd:attribute name="write-dot" type="xsd:string" use="optional"/> <xsd:attribute name="configuration-ref" default="hadoopConfiguration"> <xsd:annotation> <xsd:documentation source="java:org.apache.hadoop.conf.Configuration"><![CDATA[ Reference to the Hadoop configuration. Defaults to 'hadoopConfiguration'.]]></xsd:documentation> <xsd:appinfo> <tool:annotation kind="ref"> <tool:expected-type type="org.apache.hadoop.conf.Configuration" /> </tool:annotation> </xsd:appinfo> </xsd:annotation> </xsd:attribute> </xsd:extension> </xsd:complexContent> </xsd:complexType> </xsd:element> </xsd:schema>