1. What’s new in Spring Integration 4.2?

This chapter provides an overview of the new features and improvements that have been introduced with Spring Integration 4.1. If you are interested in more details, please see the Issue Tracker tickets that were resolved as part of the 4.1 development process.

1.1 New Components

1.1.1 Major JMX Rework

A new MetricsFactory strategy interface has been introduced. This, together with other changes in the JMX infrastructure provides much more control over JMX configuration and runtime performance.

However, this has some important implications for (some) user environments.

For complete details, see the section called “JMX Improvements”.

1.1.2 MongodDB Metadata Store

The MongoDbMetadataStore is now available. For more information, see Section 21.3.2, “MongodDB Metadata Store”.

1.1.3 SecuredChannel Annotation

The @SecuredChannel annotation has been introduced, replacing the deprecated ChannelSecurityInterceptorFactoryBean. For more information, see Appendix D, Security in Spring Integration.

1.1.4 FileSplitter

The FileSplitter, which splits text files into lines, was added in 4.1.2. It now has full support in the int-file: namespace; see Section 13.5, “File Splitter” for more information.

1.1.5 Zookeeper Support

Zookeeper support has been added to the framework to assist when running on a clustered/multi-host environment.

  • ZookeeperMetadataStore
  • ZookeeperLockRegistry
  • Zookeeper Leadership

See Chapter 35, Zookeeper Support for more information.

1.2 General Changes

1.2.1 Wire Tap

As an alternative to the existing selector attribute, the <wire-tap/> now supports the selector-expression attribute.

1.2.2 File Changes

The <int-file:outbound-channel-adapter> and <int-file:outbound-gateway> now support an append-new-line attribute. If set to true, a new line is appended to the file after a message is written. The default attribute value is false.

The ignore-hidden attribute has been introduced for the <int-file:inbound-channel-adapter> to pick up or not the hidden files from the source directory. It is true by default.

The FileWritingMessageHandler now also accepts InputStream as a valid message payload type.

The HeadDirectoryScanner can now be used with other FileListFilter s.

See Chapter 13, File Support for more information.

1.2.3 Class Package Change

The ScatterGatherHandler class has been moved from the org.springframework.integration.handler to the org.springframework.integration.scattergather.

1.2.4 TCP Changes

TCP Serializers

The TCP Serializers no longer flush() the OutputStream; this is now done by the TcpNxxConnection classes. If you are using the serializers directly within user code, you may have to flush() the OutputStream.

Server Socket Exceptions

TcpConnectionServerExceptionEvent s are now published whenever an unexpected exception occurs on a TCP server socket (also added to 4.1.3, 4.0.7). See Section 29.5, “TCP Connection Events” for more information.

TCP Gateway Remote Timeout

The TcpOutboundGateway now supports remote-timeout-expression as an alternative to the existing remote-timeout attribute. This allows setting the timeout based on each message.

Also, the remote-timeout no longer defaults to the same value as reply-timeout which has a completely different meaning.

See Table 29.7, “TCP Outbound Gateway Attributes” for more information.

TCP SSLSession Available for Header Mapping

TcpConnection s now support getSslSession() to enable users to extract information from the session to add to message headers.

See Section 29.12, “IP Message Headers” for more information.

TCP Events

New events are now published whenever a correlation exception occurs - for example sending a message to a non-existent socket. See Section 29.5, “TCP Connection Events” for more information.

1.2.5 @InboundChannelAdapter

Previously, the @Poller on an inbound channel adapter defaulted the maxMessagesPerPoll attribute to -1 (infinity). This was inconsistent with the XML configuration of <inbound-channel-adapter/> s, which defaults to 1. The annotation now defaults this attribute to 1.

1.2.6 API Changes

o.s.integtation.util.FunctionIterator now requires a o.s.integration.util.Function instead of a reactor.function.Function. This was done to remove an unnecessary hard dependency on Reactor. Any uses of this iterator will need to change the import.

Of course, Reactor is still supported for functionality such as the Promise gateway; the dependency was removed for those users who don’t need it.

1.2.7 JMS Changes

The error-channel now is used for the conversion errors, which have caused a transaction rollback and message redelivery previously.

See Section 19.2, “Message-Driven Channel Adapter” for more information.

1.2.8 Conditional Pollers

Much more flexibility is now provided for dynamic polling.

See Section 3.2.3, “Conditional Pollers for Message Sources” for more information.

1.2.9 AMQP Changes

The <int-amqp:outbound-gateway> now supports confirm-correlation-expression and confirm-(n)ack-channel attributes with similar purpose as for <int-amqp:outbound-channel-adapter>.

See Chapter 10, AMQP Support for more information.

1.2.10 XPath Splitter Improvements

The XPathMessageSplitter (<int-xml:xpath-splitter>) now allows the configuration of output-properties for the internal javax.xml.transform.Transformer and supports an Iterator mode (defaults to true) for the xpath evaluation org.w3c.dom.NodeList result.

See Section 33.5, “Splitting XML Messages” for more information.

1.2.11 HTTP Changes

The HTTP Inbound Endpoints (<int-http:inbound-channel-adapter> and <int-http:inbound-gateway>) now allow the configuration of Cross-Origin Resource Sharing (CORS).

See Section 16.4.4, “Cross-Origin Resource Sharing (CORS) Support” for more information.

1.2.12 Persistent File List Filter Changes

The AbstractPersistentFileListFilter has a new property flushOnUpdate which, when set to true, will flush() the metadata store if it implements Flushable (e.g. the PropertiesPersistenMetadataStore).

1.2.13 Gateway Changes

Gateway Methods can Return CompletableFuture<?>

When using Java 8, gateway methods can now return CompletableFuture<?>. See the section called “CompletableFuture” for more information.

MessagingGateway Annotation

The request and reply timeout properties are now String instead of Long to allow configuration with property placeholders or SpEL. See Section 7.3.6, “@MessagingGateway Annotation”.

1.2.14 Aggregator Changes

Aggregator Performance

This release includes some performance improvements for aggregating components (aggregator, resequencer, etc), by more efficiently removing messages from groups when they are released. New methods (removeMessagesFromGroup) have been added to the message store. Set the removeBatchSize property (default 100) to adjust the number of messages deleted in each operation. Currently, JDBC, Redis and MongoDB message stores support this property.

Output MessageGroupProcessor

When using a ref or innner bean for the aggregator, it is now possible to bind a MessageGroupProcessor directly. In addition, a SimpleMessageGroupProcessor is provided that simply returns the collection of messages in the group. When an output processor produces a collection of Message<?>, the aggregator releases those messages individually. Configuring the SimpleMessageGroupProcessor makes the aggregator a message barrier, were messages are held up until they all arrive, and are then released individually. See Section 5.4, “Aggregator” for more information.