Changes Between 2.2 and 3.0

The HTTP module now provides powerful request mapping support for inbound endpoints. We replaced the UriPathHandlerMapping class with IntegrationRequestMappingHandlerMapping, which is registered under the bean name of integrationRequestMappingHandlerMapping in the application context. Upon parsing of the HTTP inbound endpoint, either a new IntegrationRequestMappingHandlerMapping bean is registered or an existing bean is reused. To achieve flexible request mapping configuration, Spring Integration provides the <request-mapping/> child element for <http:inbound-channel-adapter/> and the <http:inbound-gateway/>. Both HTTP inbound endpoints are now fully based on the request mapping infrastructure that was introduced with Spring MVC 3.1. For example, multiple paths are supported on a single inbound endpoint. For more information see HTTP Namespace Support.

We added a new IntegrationEvaluationContextFactoryBean to allow configuration of custom PropertyAccessor implementations and functions for use in SpEL expressions throughout the framework. For more information, see Spring Expression Language (SpEL).

To customize the SpEL EvaluationContext with static Method functions, we introduced the <spel-function/> component. We also added two built-in functions: #jsonPath and #xpath. For more information, see SpEL Functions.

To customize the SpEL EvaluationContext with PropertyAccessor implementations, we added the <spel-property-accessors/> component. For more information, see Property Accessors.

We added a new Redis-based MetadataStore implementation. You can use the RedisMetadataStore to maintain the state of a MetadataStore across application restarts. This new MetadataStore implementation can be used with adapters, such as:

We added new queue-based components. We added the <int-redis:queue-inbound-channel-adapter/> and <int-redis:queue-outbound-channel-adapter/> components to perform 'right pop' and 'left push' operations, respectively, on a Redis List.

For more information, “see Redis Support”.

You can now instruct the framework to store reply channels and error channels in a registry for later resolution. This is useful for cases where the replyChannel or errorChannel might be lost (for example, when serializing a message). See Header Enricher for more information.

In addition to the existing eMongoDbMessageStore, we introduced a new ConfigurableMongoDbMessageStore. This provides a more robust and flexible implementation of MessageStore for MongoDB. It does not have backward compatibility with the existing store, but we recommend using it for new applications. Existing applications can use it, but messages in the old store are not available. See MongoDb Support for more information.

Building on the 2.2 SyslogToMapTransformer, Spring Integration 3.0 introduces UDP and TCP inbound channel adapters especially tailored for receiving SYSLOG messages. For more information, see Syslog Support.

We added file inbound channel adapters that use the tail command to generate messages when lines are added to the end of text files. See 'tail’ing Files.

We added <int-jmx:tree-polling-channel-adapter/>. This adapter queries the JMX MBean tree and sends a message with a payload that is the graph of objects that match the query. By default, the MBeans are mapped to primitives and simple Objects (such as Map, List, and arrays). It permits simple transformation to, for example, JSON.

The IntegrationMBeanExporter now allows the configuration of a custom ObjectNamingStrategy by using the naming-strategy attribute.

For more information, see JMX Support.

TcpConnection instances now emit ApplicationEvent instances (specifically TcpConnectionEvent instances) when connections are opened or closed or when an exception occurs. This change lets applications be informed of changes to TCP connections by using the normal Spring ApplicationListener mechanism.

We renamed AbstractTcpConnection to TcpConnectionSupport. Custom connections that are subclasses of this class can use its methods to publish events. Similarly, we renamed AbstractTcpConnectionInterceptor to TcpConnectionInterceptorSupport.

In addition, we added <int-ip:tcp-connection-event-inbound-channel-adapter/>. By default, this adapter sends all TcpConnectionEvent instances to a Channel.

Further, the TCP connection factories now provide a new method called getOpenConnectionIds(), which returns a list of identifiers for all open connections. It lets applications broadcast to all open connections, among other uses.

Finally, the connection factories also provide a new method called closeConnection(String connectionId), which lets applications explicitly close a connection by using its ID.

For more information see TCP Connection Events.

The <int:inbound-channel-adapter/> now supports using <expression/> and <script/> child elements to create a MessageSource. See Channel Adapter Expressions and Scripts.

The content enricher now provides configuration for <header/> child elements, to enrich the outbound message with headers based on the reply message from the underlying message flow. For more information see Payload Enricher.

Previously, message IDs were generated by using the JDK UUID.randomUUID() method. With this release, the default mechanism has been changed to use a more efficient and significantly faster algorithm. In addition, we added the ability to change the strategy used to generate message IDs. For more information see Message ID Generation.

You can now set common headers across all gateway methods, and we added more options for adding information to the message about which method was invoked.

You can now entirely customize the way that gateway method calls are mapped to messages.

The GatewayMethodMetadata is now a public class. It lets you programmatically configure the GatewayProxyFactoryBean from Java.

For more information, see Messaging Gateways.

For more information, see HTTP Support.

For more information, see “JSON Transformers” in Transformer.

Previously, the id attribute for elements within a <chain> was ignored and, in some cases, disallowed. Now, the id attribute is allowed for all elements within a <chain>. The bean names of chain elements is a combination of the surrounding chain’s id and the id of the element itself. For example: 'myChain$child.myTransformer.handler'. For more information see, Message Handler Chain.

The AbstractCorrelatingMessageHandler provides a new property called empty-group-min-timeout to allow empty group expiry to run on a longer schedule than expiring partial groups. Empty groups are not removed from the MessageStore until they have not been modified for at least this number of milliseconds. For more information, see Configuring an Aggregator with XML.

New FileListFilter implementations that use a persistent MetadataStore are now available. You can use these to prevent duplicate files after a system restart. See Reading Files, FTP Inbound Channel Adapter, and SFTP Inbound Channel Adapter for more information.

We introduced a new variables attribute for scripting components. In addition, variable bindings are now allowed for inline scripts. See Groovy support and Scripting Support for more information.

Previously, when configuring LoadBalancingStrategy on the channel’s dispatcher child element, the only available option was to use a pre-defined enumeration of values which did not let developers set a custom implementation of the LoadBalancingStrategy. You can now use load-balancer-ref to provide a reference to a custom implementation of the LoadBalancingStrategy. For more information, see DirectChannel.

Previously, sending to a <publish-subscribe-channel/> that had no subscribers would return a false result. If used in conjunction with a MessagingTemplate, this would result in an exception being thrown. Now, the PublishSubscribeChannel has a property called minSubscribers (default: 0). If the message is sent to at least the minimum number of subscribers, the send operation is deemed to be successful (even if the number is zero). If an application expects to get an exception under these conditions, set the minimum subscribers to at least 1.

The FTP, SFTP and FTPS endpoints no longer cache sessions by default.

We removed the deprecated cached-sessions attribute from all endpoints. Previously, the embedded caching mechanism controlled by this attribute’s value did not provide a way to limit the size of the cache, which could grow indefinitely. Release 2.1 introduced CachingConnectionFactory, and it became the preferred (and is now the only) way to cache sessions.

CachingConnectionFactory now provides a new method: resetCache(). This method immediately closes idle sessions and causes in-use sessions to be closed as and when they are returned to the cache.

The DefaultSftpSessionFactory (in conjunction with a CachingSessionFactory) now supports multiplexing channels over a single SSH connection (SFTP Only).

All outbound gateways (such as <jdbc:outbound-gateway/> or <jms:outbound-gateway/>) are designed for 'request-reply' scenarios. A response is expected from the external service and is published to the reply-channel or the replyChannel message header. However, there are some cases where the external system might not always return a result (for example, a <jdbc:outbound-gateway/> when a SELECT ends with an empty ResultSet or perhaps a one-way web service). Consequently, developers needed an option to configure whether or not a reply is required. For this purpose, we introduced the requires-reply attribute for outbound gateway components. In most cases, the default value for requires-reply is true. If there is no result, a ReplyRequiredException is thrown. Changing the value to false means that, if an external service does not return anything, the message flow ends at that point, similar to an outbound channel adapter.

Note that the requiresReply property was previously present but set to false in the AbstractReplyProducingMessageHandler, and there was no way to configure it on outbound gateways by using the XML namespace.

Previously, the <int-amqp:outbound-gateway/> mapped headers before invoking the message converter, and the converter could overwrite headers such as content-type. The outbound adapter maps the headers after the conversion, which means headers like content-type from the outbound Message (if present) are used.

Starting with this release, the gateway now maps the headers after the message conversion, consistent with the adapter. If your application relies on the previous behavior (where the converter’s headers overrode the mapped headers), you either need to filter those headers (before the message reaches the gateway) or set them appropriately. The headers affected by the SimpleMessageConverter are content-type and content-encoding. Custom message converters may set other headers.

For more complex database-specific types not supported by the standard CallableStatement.getObject method, we introduced two new additional attributes to the <sql-parameter-definition/> element with OUT-direction:

The row-mapper attribute of the stored procedure inbound channel adapter <returning-resultset/> child element now supports a reference to a RowMapper bean definition. Previously, it contained only a class name (which is still supported).

For more information, see Stored Procedures.

The web service outbound gateway 'uri' attribute now supports <uri-variable/> substitution for all URI schemes supported by Spring Web Services. For more information, see Outbound URI Configuration.

The Redis inbound channel adapter can now use a null value for the serializer property, with the raw data being the message payload.

The Redis outbound channel adapter now has the topic-expression property to determine the Redis topic for the Message at runtime.

The Redis inbound channel adapter, in addition to the existing topics attribute, now has the topic-patterns attribute.

For more information, see Redis Support.

Previously, when a <filter/> had a <request-handler-advice-chain/>, the discard action was all performed within the scope of the advice chain (including any downstream flow on the discard-channel). The filter element now has an attribute called discard-within-advice (default: true) to allow the discard action to be performed after the advice chain completes. See Advising Filters.

Request handler advice chains can now be configured using annotations. See Advising Endpoints Using Annotations.

This transformer now correctly transforms byte[] and char[] payloads to String. For more information, see Transformer.

Payloads to persist or merge can now be of type java.lang.Iterable.

In that case, each object returned by the Iterable is treated as an entity and persisted or merged by using the underlying EntityManager. Null values returned by the iterator are ignored.

The JPA adapters now have additional attributes to optionally flush and clear entities from the associated persistence context after performing persistence operations.

Retrieving gateways had no mechanism to specify the first record to be retrieved, which is a common use case. The retrieving gateways now support specifying this parameter by adding the first-result and first-result-expression attributes to the gateway definition. For more information, see Retrieving Outbound Gateway.

The JPA retrieving gateway and inbound adapter now have an attribute to specify the maximum number of results in a result set as an expression. In addition, we introduced the max-results attribute to replace max-number-of-results, which has been deprecated. max-results and max-results-expression are used to provide the maximum number of results or an expression to compute the maximum number of results, respectively, in the result set.

For more information, see JPA Support.

Previously, the <delayer> provided a delay-header-name attribute to determine the delay value at runtime. In complex cases, the <delayer> had to be preceded with a <header-enricher>. Spring Integration 3.0 introduced the expression attribute and expression child element for dynamic delay determination. The delay-header-name attribute is now deprecated, because you can specify the header evaluation in the expression. In addition, we introduced the ignore-expression-failures to control the behavior when an expression evaluation fails. For more information, see Delayer.

Spring Integration 3.0 adds a new set of DDL scripts for MySQL version 5.6.4 and higher. Now MySQL supports fractional seconds and is thus improving the FIFO ordering when polling from a MySQL-based message store. For more information, see The Generic JDBC Message Store.

Previously, if an IMAP idle connection failed, it was logged, but there was no mechanism to inform an application. Such exceptions now generate ApplicationEvent instances. Applications can obtain these events by using an <int-event:inbound-channel-adapter> or any ApplicationListener configured to receive an ImapIdleExceptionEvent (or one of its super classes).

The TCP connection factories now enable the configuration of a flexible mechanism to transfer selected headers (as well as the payload) over TCP. A new TcpMessageMapper enables the selection of the headers, and you need to configure an appropriate serializer or deserializer to write the resulting Map to the TCP stream. We added a MapJsonSerializer as a convenient mechanism to transfer headers and payload over TCP. For more information, see Transferring Headers.

Previously, when configuring a <message-driven-channel-adapter/>, if you wished to use a specific TaskExecutor, you had to declare a container bean and provide it to the adapter by setting the container attribute. We added the task-executor, letting it be set directly on the adapter. This is in addition to several other container attributes that were already available.

You can now specify the transformer factory class name by setting the transformer-factory-class attribute. See XsltPayloadTransformer.