Changes between 4.0 and 4.1

The messaging gateway methods now support a Reactor Promise return type. See Asynchronous Gateway.

The WebSocket module is now available. It is fully based on the Spring WebSocket and Spring Messaging modules and provides an <inbound-channel-adapter> and an <outbound-channel-adapter>. See WebSockets Support for more information.

We implemented the scatter-gather enterprise integration pattern. See Scatter-Gather for more information.

We added the routing slip EIP pattern implementation. See Routing Slip for more information.

We added the idempotent receiver enterprise integration pattern implementation by adding the <idempotent-receiver> component in XML or the IdempotentReceiverInterceptor and IdempotentReceiver annotations for Java configuration. See Idempotent Receiver Enterprise Integration Pattern and the Javadoc for more information.

We added the Boon JsonObjectMapper for the JSON transformers. See Transformer for more information.

We added the <redis-queue-inbound-gateway> and <redis-queue-outbound-gateway> components. See Redis Queue Inbound Gateway and Redis Queue Outbound Gateway.

We added the PollSkipAdvice, which you can use within the <advice-chain> of the <poller> to determine if the current poll should be suppressed (skipped) by some condition that you implement with PollSkipStrategy. See Poller for more information.

Elements that use a message listener container (inbound endpoints and channel) now support the missing-queues-fatal attribute. See AMQP Support for more information.

The AMQP outbound endpoints support a new property called lazy-connect (default: true). When true, the connection to the broker is not established until the first message arrives (assuming there are no inbound endpoints, which always try to establish the connection during startup). When set to false, an attempt to establish the connection is made during application startup. See AMQP Support for more information.

The SimpleMessageStore no longer makes a copy of the group when calling getMessageGroup(). See xref:message-store.adoc#sms-caution for more information.

The <ws:outbound-gateway/> now provides an encode-uri attribute to allow disabling the encoding of the URI object before sending the request.

The <http:inbound-channel-adapter> can now be configured with a status-code-expression to override the default 200 OK status. See HTTP Namespace Support for more information.

You can now configure the MQTT channel adapters to connect to multiple servers — for example, to support High Availability (HA). See MQTT Support for more information.

The MQTT message-driven channel adapter now supports specifying the QoS setting for each subscription. See Inbound (Message-driven) Channel Adapter for more information.

The MQTT outbound channel adapter now supports asynchronous sends, avoiding blocking until delivery is confirmed. See Outbound Channel Adapter for more information.

It is now possible to programmatically subscribe to and unsubscribe from topics at runtime. See Inbound (Message-driven) Channel Adapter for more information.

The FTP and SFTP outbound channel adapters now support appending to remote files and taking specific actions when a remote file already exists. The remote file templates now also supports this, as well as rmdir() and exists(). In addition, the remote file templates provide access to the underlying client object, enabling access to low-level APIs.

See FTP/FTPS Adapters and SFTP Adapters for more information.

Splitter components now support an Iterator as the result object for producing output messages. See Splitter for more information.

Aggregator instancess now support a new attribute expire-groups-upon-timeout. See Aggregator for more information.

We added a null-result-expression attribute, which is evaluated and returned if <enricher> returns null. You can add it in <header> and <property>. See Content Enricher for more information.

We added an error-channel attribute, which is used to handle an error flow if an Exception occurs downstream of the request-channel. This lets you return an alternative object to use for enrichment. See Content Enricher for more information.

The <header-enricher/> element’s <header-channels-to-string/> child element can now override the header channel registry’s default time for retaining channel mappings. See Header Channel Registry for more information.

We made improvements to the orderly shutdown algorithm. See Orderly Shutdown for more information.

The RecipientListRouter now provides several management operations to configure recipients at runtime. With that, you can now configure the <recipient-list-router> without any <recipient> from the start. See RecipientListRouterManagement for more information.

The AbstractHeaderMapper implementation now provides the additional NON_STANDARD_HEADERS token to map any user-defined headers, which are not mapped by default. See AMQP Message Headers for more information.

We introduced the template-channel-transacted attribute for AMQP MessageChannel instances. See AMQP-backed Message Channels for more information.

The default syslog message converter now has an option to retain the original message in the payload while still setting the headers. See Syslog Inbound Channel Adapter for more information.

In addition to the Promise return type mentioned earlier, gateway methods may now return a ListenableFuture, introduced in Spring Framework 4.0. You can also disable asynchronous processing in the gateway, letting a downstream flow directly return a Future. See Asynchronous Gateway.

Aggregator and Resequencer now support <expire-advice-chain/> and <expire-transactional/> child elements to advise the forceComplete operation. See Configuring an Aggregator with XML for more information.

The <int:outbound-channel-adapter/> now supports the <script/> child element. The underlying script must have a void return type or return null. See Groovy support and Scripting Support.

When a message group in a resequencer times out (using group-timeout or a MessageGroupStoreReaper), late arriving messages are now, by default, discarded immediately. See Resequencer.

Spring Integration now consistently handles the Java 8’s Optional type. See Configuring Service Activator.

The QueueChannel backed Queue type has been changed from BlockingQueue to the more generic Queue. This change allows the use of any external Queue implementation (for example, Reactor’s PersistentQueue). See QueueChannel Configuration.

The ChannelInterceptor now supports additional afterSendCompletion() and afterReceiveCompletion() methods. See Channel Interceptors.

Since version 4.1.1 there is a change of behavior if you explicitly set the mail.[protocol].peek JavaMail property to false (where [protocol] is imap or imaps). See xref:changes-4.0-4.1.adoc#x4.1-mail-peek.