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FTP Outbound Gateway
The FTP outbound gateway provides a limited set of commands to interact with a remote FTP or FTPS server. The supported commands are:
-
ls
(list files) -
nlst
(list file names) -
get
(retrieve file) -
mget
(retrieve file(s)) -
rm
(remove file(s)) -
mv
(move/rename file) -
put
(send file) -
mput
(send multiple files)
Using the ls
Command
ls
lists remote files and supports the following options:
-
-1
: Retrieve a list of file names. The default is to retrieve a list ofFileInfo
objects. -
-a
: Include all files (including those starting with '.') -
-f
: Do not sort the list -
-dirs
: Include directories (they are excluded by default) -
-links
: Include symbolic links (they are excluded by default) -
-R
: List the remote directory recursively
In addition, filename filtering is provided, in the same manner as the inbound-channel-adapter
.
See FTP Inbound Channel Adapter.
The message payload resulting from an ls
operation is a list of file names or a list of FileInfo
objects.
These objects provide information such as modified time, permissions, and other details.
The remote directory that the ls
command acted on is provided in the file_remoteDirectory
header.
When using the recursive option (-R
), the fileName
includes any subdirectory elements, representing a relative path to the file (relative to the remote directory).
If the -dirs
option is included, each recursive directory is also returned as an element in the list.
In this case, it is recommended that you not use the -1
option, because you would not be able to distinguish files from directories, which you can do with the FileInfo
objects.
Starting with version 4.3, the FtpSession
supports null
for the list()
and listNames()
methods.
Therefore, you can omit the expression
attribute.
For convenience, Java configuration has two constructors that do not have an expression
argument.
or LS
, NLST
, PUT
and MPUT
commands, null
is treated as the client working directory, according to the FTP protocol.
All other commands must be supplied with the expression
to evaluate the remote path against the request message.
You can set the working directory with the FTPClient.changeWorkingDirectory()
function when you extend the DefaultFtpSessionFactory
and implement the postProcessClientAfterConnect()
callback.
Using the nlst
Command
Version 5 introduced support for the nlst
command.
nlst
lists remote file names and supports only one option:
-
-f
: Do not sort the list
The message payload resulting from an nlst
operation is a list of file names.
The remote directory that the nlst
command acted on is provided in the file_remoteDirectory
header.
Unlike the -1
option for the ls
command, which uses the LIST
command, the nlst
command sends an NLST
command to the target FTP server.
This command is useful when the server does not support LIST
(due to security restrictions, for example).
The result of the nlst
operation is the names without other detail.
Therefore, the framework cannot determine if an entity is a directory, to perform filtering or recursive listing, for example.
Using the get
Command
get
retrieves a remote file.
It supports the following option:
-
-P
: Preserve the timestamp of the remote file. -
-stream
: Retrieve the remote file as a stream. -
-D
: Delete the remote file after successful transfer. The remote file is not deleted if the transfer is ignored, because theFileExistsMode
isIGNORE
and the local file already exists.
The file_remoteDirectory
header provides the remote directory name, and the file_remoteFile
header provides the file name.
The message payload resulting from a get
operation is a File
object that represents the retrieved file or an InputStream
when you use the -stream
option.
The -stream
option allows retrieving the file as a stream.
For text files, a common use case is to combine this operation with a file splitter or a stream transformer.
When consuming remote files as streams, you are responsible for closing the Session
after the stream is consumed.
For convenience, the Session
is provided in the closeableResource
header, which you can access with a convenience method on IntegrationMessageHeaderAccessor
The following example shows how to use the convenience method:
Closeable closeable = new IntegrationMessageHeaderAccessor(message).getCloseableResource();
if (closeable != null) {
closeable.close();
}
Framework components such as the file splitter and the stream transformer automatically close the session after the data is transferred.
The following example shows how to consume a file as a stream:
<int-ftp:outbound-gateway session-factory="ftpSessionFactory"
request-channel="inboundGetStream"
command="get"
command-options="-stream"
expression="payload"
remote-directory="ftpTarget"
reply-channel="stream" />
<int-file:splitter input-channel="stream" output-channel="lines" />
If you consume the input stream in a custom component, you must close the Session .
You can do so either in your custom code or by routing a copy of the message to a service-activator and using SpEL, as the following example shows:
|
<int:service-activator input-channel="closeSession"
expression="headers['closeableResource'].close()" />
Using the mget
Command
mget
retrieves multiple remote files based on a pattern and supports the following options:
-
-P
: Preserve the timestamps of the remote files. -
-R
: Retrieve the entire directory tree recursively. -
-x
: Throw an exception if no files match the pattern (otherwise an empty list is returned). -
-D
: Delete each remote file after successful transfer. The remote file is not deleted if the transfer is ignored, because theFileExistsMode
isIGNORE
and the local file already exists.
The message payload resulting from an mget
operation is a List<File>
object (that is, a List
of File
objects, each representing a retrieved file).
Starting with version 5.0, if the FileExistsMode is IGNORE , the payload of the output message no longer contains files that were not fetched due to the file already existing.
Previously, the list contained all files, including those that already existed.
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The expression used to determine the remote path should produce a result that ends with - e.g.
somedir/
will fetch the complete tree under somedir
.
Starting with version 5.0, a recursive mget
, combined with the new FileExistsMode.REPLACE_IF_MODIFIED
mode, can be used to periodically synchronize an entire remote directory tree locally.
This mode replaces the local file’s last modified timestamp with the remote timestamp, regardless of the -P
(preserve timestamp) option.
Using recursion (
-R )The pattern is ignored, and If a subdirectory is filtered, no additional traversal of that subdirectory is performed. The Typically, you would use the |
The persistent file list filters now have a boolean property forRecursion
.
Setting this property to true
, also sets alwaysAcceptDirectories
, which means that the recursive operation on the outbound gateways (ls
and mget
) will now always traverse the full directory tree each time.
This is to solve a problem where changes deep in the directory tree were not detected.
In addition, forRecursion=true
causes the full path to files to be used as the metadata store keys; this solves a problem where the filter did not work properly if a file with the same name appears multiple times in different directories.
IMPORTANT: This means that existing keys in a persistent metadata store will not be found for files beneath the top level directory.
For this reason, the property is false
by default; this may change in a future release.
Starting with version 5.0, the FtpSimplePatternFileListFilter
and FtpRegexPatternFileListFilter
can be configured to always pass directories by setting the alwaysAcceptDirectories
property to true
.
Doing so allows recursion for a simple pattern, as the following examples show:
<bean id="starDotTxtFilter"
class="org.springframework.integration.ftp.filters.FtpSimplePatternFileListFilter">
<constructor-arg value="*.txt" />
<property name="alwaysAcceptDirectories" value="true" />
</bean>
<bean id="dotStarDotTxtFilter"
class="org.springframework.integration.ftp.filters.FtpRegexPatternFileListFilter">
<constructor-arg value="^.*\.txt$" />
<property name="alwaysAcceptDirectories" value="true" />
</bean>
Once you have defined filters such as those in the preceding example, you can use one by setting the filter
property on the gateway.
Using the put
Command
The put
command sends a file to the remote server.
The payload of the message can be a java.io.File
, a byte[]
, or a String
.
A remote-filename-generator
(or expression) is used to name the remote file.
Other available attributes include remote-directory
, temporary-remote-directory
, and their *-expression
equivalents: use-temporary-file-name
and auto-create-directory
.
See the schema documentation for more information.
The message payload resulting from a put
operation is a String
that represents the full path of the file on the server after transfer.
Version 5.2 introduced the chmod
attribute, which changes the remote file permissions after upload.
You can use the conventional Unix octal format (for example, 600
allows read-write for the file owner only).
When configuring the adapter using java, you can use setChmod(0600)
.
Only applies if your FTP server supports the SITE CHMOD
subcommand.
Using the mput
Command
The mput
sends multiple files to the server and supports only one option:
-
-R
: Recursive. Send all files (possibly filtered) in the directory and its subdirectories.
The message payload must be a java.io.File
(or String
) that represents a local directory.
Since version 5.1, a collection of File
or String
is also supported.
This command supports the same attributes as the put
command.
In addition, files in the local directory can be filtered with one of mput-pattern
, mput-regex
, mput-filter
, or mput-filter-expression
.
The filter works with recursion, as long as the subdirectories themselves pass the filter.
Subdirectories that do not pass the filter are not recursed.
The message payload resulting from an mput
operation is a List<String>
object (that is, a List
of remote file paths that result from the transfer).
Version 5.2 introduced the chmod
attribute, which lets you change the remote file permissions after upload.
You can use the conventional Unix octal format (for example, 600
allows read-write for the file owner only).
When configuring the adapter with Java, you can use setChmodOctal("600")
or setChmod(0600)
.
Only applies if your FTP server supports the SITE CHMOD
subcommand.
Using the rm
Command
The rm
command removes files.
The rm
command has no options.
The message payload resulting from an rm
operation is Boolean.TRUE
if the remove was successful or Boolean.FALSE
otherwise.
The file_remoteDirectory
header provides the remote directory, and the file_remoteFile
header provides the file name.
Using the mv
Command
The mv
command moves files.
The mv
command has no options.
The expression
attribute defines the “from” path and the rename-expression
attribute defines the “to” path.
By default, the rename-expression
is headers['file_renameTo']
.
This expression must not evaluate to null or an empty String
.
If necessary, any necessary remote directories are created.
The payload of the result message is Boolean.TRUE
.
The file_remoteDirectory
header provides the original remote directory, and file_remoteFile
header provides the file name.
The new path is in the file_renameTo
header.
Starting with version 5.5.6, the remoteDirectoryExpression
can be used in the mv
command for convenience.
If the “from” file is not a full file path, the result of remoteDirectoryExpression
is used as the remote directory.
The same applies for the “to” file, for example, if the task is just to rename a remote file in some directory.
Additional Information about FTP Outbound Gateway Commands
The get
and mget
commands support the local-filename-generator-expression
attribute.
It defines a SpEL expression to generate the name of local files during the transfer.
The root object of the evaluation context is the request message.
The remoteFileName
variable, which is particularly useful for mget
, is also available — for example, local-filename-generator-expression="#remoteFileName.toUpperCase() + headers.something"
.
The get
and mget
commands support the local-directory-expression
attribute.
It defines a SpEL expression to generate the name of local directories during the transfer.
The root object of the evaluation context is the request message but.
The remoteDirectory
variable, which is particularly useful for mget
, is also available — for example: local-directory-expression="'/tmp/local/' + #remoteDirectory.toUpperCase() + headers.something"
.
This attribute is mutually exclusive with the local-directory
attribute.
For all commands, the 'expression' property of the gateway provides the path on which the command acts.
For the mget
command, the expression might evaluate to '', meaning to retrieve all files, or 'somedirectory/', and so on.
The following example shows a gateway configured for an ls
command:
<int-ftp:outbound-gateway id="gateway1"
session-factory="ftpSessionFactory"
request-channel="inbound1"
command="ls"
command-options="-1"
expression="payload"
reply-channel="toSplitter"/>
The payload of the message sent to the toSplitter
channel is a list of String
objects that each contain the name of a file.
If the command-options
attribute was omitted, it holds FileInfo
objects.
It uses space-delimited options — for example, command-options="-1 -dirs -links"
.
Starting with version 4.2, the GET
, MGET
, PUT
and MPUT
commands support a FileExistsMode
property (mode
when using the namespace support).
This affects the behavior when the local file exists (GET
and MGET
) or the remote file exists (PUT
and MPUT
).
Supported modes are REPLACE
, APPEND
, FAIL
, and IGNORE
.
For backwards compatibility, the default mode for PUT
and MPUT
operations is REPLACE
.
For GET
and MGET
operations, the default is FAIL
.
Starting with version 5.0, the setWorkingDirExpression()
(working-dir-expression
in XML) option is provided on the FtpOutboundGateway
(<int-ftp:outbound-gateway>
in XML).
It lets you change the client working directory at runtime.
The expression is evaluated against the request message.
The previous working directory is restored after each gateway operation.
Configuring with Java Configuration
The following Spring Boot application shows an example of how to configure the outbound gateway with Java configuration:
@SpringBootApplication
public class FtpJavaApplication {
public static void main(String[] args) {
new SpringApplicationBuilder(FtpJavaApplication.class)
.web(false)
.run(args);
}
@Bean
public SessionFactory<FTPFile> ftpSessionFactory() {
DefaultFtpSessionFactory sf = new DefaultFtpSessionFactory();
sf.setHost("localhost");
sf.setPort(port);
sf.setUsername("foo");
sf.setPassword("foo");
sf.setTestSession(true);
return new CachingSessionFactory<FTPFile>(sf);
}
@Bean
@ServiceActivator(inputChannel = "ftpChannel")
public MessageHandler handler() {
FtpOutboundGateway ftpOutboundGateway =
new FtpOutboundGateway(ftpSessionFactory(), "ls", "'my_remote_dir/'");
ftpOutboundGateway.setOutputChannelName("lsReplyChannel");
return ftpOutboundGateway;
}
}
Configuring with the Java DSL
The following Spring Boot application shows an example of how to configure the outbound gateway with the Java DSL:
@SpringBootApplication
public class FtpJavaApplication {
public static void main(String[] args) {
new SpringApplicationBuilder(FtpJavaApplication.class)
.web(false)
.run(args);
}
@Bean
public SessionFactory<FTPFile> ftpSessionFactory() {
DefaultFtpSessionFactory sf = new DefaultFtpSessionFactory();
sf.setHost("localhost");
sf.setPort(port);
sf.setUsername("foo");
sf.setPassword("foo");
sf.setTestSession(true);
return new CachingSessionFactory<FTPFile>(sf);
}
@Bean
public FtpOutboundGatewaySpec ftpOutboundGateway() {
return Ftp.outboundGateway(ftpSessionFactory(),
AbstractRemoteFileOutboundGateway.Command.MGET, "payload")
.options(AbstractRemoteFileOutboundGateway.Option.RECURSIVE)
.regexFileNameFilter("(subFtpSource|.*1.txt)")
.localDirectoryExpression("'localDirectory/' + #remoteDirectory")
.localFilenameExpression("#remoteFileName.replaceFirst('ftpSource', 'localTarget')");
}
@Bean
public IntegrationFlow ftpMGetFlow(AbstractRemoteFileOutboundGateway<FTPFile> ftpOutboundGateway) {
return f -> f
.handle(ftpOutboundGateway)
.channel(c -> c.queue("remoteFileOutputChannel"));
}
}
Outbound Gateway Partial Success (mget
and mput
)
When you perform operations on multiple files (by using mget
and mput
), an exception can occur some time after one or more files have been transferred.
In this case (starting with version 4.2), a PartialSuccessException
is thrown.
As well as the usual MessagingException
properties (failedMessage
and cause
), this exception has two additional properties:
-
partialResults
: The successful transfer results. -
derivedInput
: The list of files generated from the request message (for example, local files to transfer for anmput
).
These attributes let you determine which files were successfully transferred and which were not.
In the case of a recursive mput
, the PartialSuccessException
may have nested PartialSuccessException
occurrences.
Consider the following directory structure:
root/
|- file1.txt
|- subdir/
| - file2.txt
| - file3.txt
|- zoo.txt
If the exception occurs on file3.txt
, the PartialSuccessException
thrown by the gateway has derivedInput
of file1.txt
, subdir
, and zoo.txt
and partialResults
of file1.txt
.
Its cause
is another PartialSuccessException
with derivedInput
of file2.txt
and file3.txt
and partialResults
of file2.txt
.