[[migration-3.0-4.0]]
= Changes between 3.0 and 4.0

See the https://github.com/spring-projects/spring-integration/wiki/Spring-Integration-3.0-to-4.0-Migration-Guide[Migration Guide] for important changes that might affect your applications.
You can find migration guides for all versions back to 2.1 on the https://github.com/spring-projects/spring-integration/wiki[wiki].

[[x4.0-new-components]]
== New Components

Version 4.0 added a number of new components.

[[x4.0-mqtt]]
=== MQTT Channel Adapters

The MQTT channel adapters (previously available in the Spring Integration Extensions repository) are now available as part of the normal Spring Integration distribution.
See xref:mqtt.adoc[MQTT Support].

[[x4.0-enable-configuration]]
=== `@EnableIntegration`

We added the `@EnableIntegration` annotation to permit declaration of standard Spring Integration beans when using `@Configuration` classes.
See xref:configuration/annotations.adoc[Annotation Support] for more information.

[[x4.0-component-scan]]
=== `@IntegrationComponentScan`

We added the `@IntegrationComponentScan` annotation to permit classpath scanning for Spring Integration-specific components.
See xref:configuration/annotations.adoc[Annotation Support] for more information.

[[x4.0-message-history]]
=== "`@EnableMessageHistory`"

You can now enable message history with the `@EnableMessageHistory` annotation in a `@Configuration` class.
In addition, a JMX MBean can modify the message history settings.
Also, `MessageHistory` can track auto-created `MessageHandler` instances for annotated endpoints (such as `@ServiceActivator`, `@Splitter`, and others).
For more information, see xref:message-history.adoc[Message History].

[[x4.0-messaging-gateway]]
=== `@MessagingGateway`

You can now configure messaging gateway interfaces with the `@MessagingGateway` annotation.
It is an analogue of the `<int:gateway/>` XML element.
For more information, see xref:gateway.adoc#messaging-gateway-annotation[`@MessagingGateway` Annotation].

[[x4.0-boot]]
=== Spring Boot `@EnableAutoConfiguration`

As well as the `@EnableIntegration` annotation mentioned earlier, we introduced a hook to allow the Spring Integration infrastructure beans to be configured with Spring Boot's `@EnableAutoConfiguration` annotation.
For more information, see https://docs.spring.io/spring-boot/docs/current/reference/html/using-boot-auto-configuration.html["`Auto-configuration`"] in the Spring Boot Reference Guide.

[[x4.0-global-channel-interceptor]]
=== `@GlobalChannelInterceptor`

As well as the `@EnableIntegration` annotation mentioned above, we introduced the `@GlobalChannelInterceptor` annotation.
For more information, see xref:configuration/annotations.adoc[Annotation Support].

[[x4.0-integration-converter]]
=== `@IntegrationConverter`

We introduced the `@IntegrationConverter` annotation as an analogue of the `<int:converter/>` component.
For more information, see xref:configuration/annotations.adoc[Annotation Support].

[[x4.0-enable-publisher]]
=== `@EnablePublisher`

We added the `@EnablePublisher` annotation to allow the specification of a `default-publisher-channel` for `@Publisher` annotations.
See xref:configuration/annotations.adoc[Annotation Support] for more information.

[[x4.0-redis-cms]]
=== Redis Channel Message Stores

We added a Redis `MessageGroupStore` that is optimized for use when backing a `QueueChannel` for persistence.
For more information, see xref:redis.adoc#redis-cms[Redis Channel Message Stores].

We added a Redis `ChannelPriorityMessageStore`.
You can use it to retrieve messages by priority.
For more information, see xref:redis.adoc#redis-cms[Redis Channel Message Stores].

[[x4.0-priority-channel-mondodb]]
=== MongodDB Channel Message Store

The MongoDB support now provides the `MongoDbChannelMessageStore`, which is a channel-specific `MessageStore` implementation.
With `priorityEnabled = true`, you can use it in `<int:priority-queue>` elements to achieve priority order polling of persisted messages.
For more information see xref:mongodb.adoc#mongodb-priority-channel-message-store[MongoDB Channel Message Store].

[[x4.0-MBeanExport-annotation]]
=== `@EnableIntegrationMBeanExport`

You can now enable the `IntegrationMBeanExporter` with the `@EnableIntegrationMBeanExport` annotation in a `@Configuration` class.
For more information, see xref:jmx.adoc#jmx-mbean-exporter[MBean Exporter].

[[x4.0-channel-security-interceptor]]
=== `ChannelSecurityInterceptorFactoryBean`

`ChannelSecurityInterceptorFactoryBean` now supports configuration of Spring Security for message channels that use `@Configuration` classes.
For more information, see xref:security.adoc[Security in Spring Integration].

[[x4.0-redis-outbound-gateway]]
=== Redis Command Gateway

The Redis support now provides the `<outbound-gateway>` component to perform generic Redis commands by using the `RedisConnection#execute` method.
For more information, see xref:redis.adoc#redis-outbound-gateway[Redis Outbound Command Gateway].

[[x4.0-redis-lock-registry]]
=== `RedisLockRegistry`

The `RedisLockRegistry` is now available to support global locks visible to multiple application instances and servers.
These can be used with aggregating message handlers across multiple application instances such that group release occurs on only one instance.
For more information, see xref:redis.adoc#redis-lock-registry[Redis Lock Registry] and xref:overview.adoc#overview-endpoints-aggregator[Aggregator].

[[x4.0-poller-annotation]]
=== `@Poller`

Annotation-based messaging configuration can now have a `poller` attribute.
This means that methods annotated with `@ServiceActivator`, `@Aggregator`, and similar annotations can now use an `inputChannel` that is a reference to a `PollableChannel`.
For more information, see xref:configuration/annotations.adoc[Annotation Support].

[[x4.0-inbound-channel-adapter-annotation]]
=== `@InboundChannelAdapter` and `SmartLifecycle` for Annotated Endpoints

We added the `@InboundChannelAdapter` method annotation.
It is an analogue of the `<int:inbound-channel-adapter>` XML component.
In addition, all messaging annotations now provide `SmartLifecycle` options.
For more information, see xref:configuration/annotations.adoc[Annotation Support].

[[x4.0-twitter-sog]]
=== Twitter Search Outbound Gateway

We added a new twitter endpoint: `<int-twitter-search-outbound-gateway/>`.
Unlike the search inbound adapter, which polls by using the same search query each time, the outbound gateway allows on-demand customized queries.
For more information, see https://github.com/spring-projects/spring-integration-extensions/tree/main/spring-integration-social-twitter[Spring Integration Social Twitter].

[[x4.0-bridge-annotations]]
=== `@BridgeFrom` and `@BridgeTo` Annotations

We introduced `@BridgeFrom` and `@BridgeTo` `@Bean` method annotations to mark `MessageChannel` beans in `@Configuration` classes.
For more information, see xref:configuration/annotations.adoc[Annotation Support].

[[x4.0-meta-messaging-annotations]]
=== Meta-messaging Annotations

Messaging annotations (`@ServiceActivator`, `@Router`, `@MessagingGateway`, and others) can now be configured as meta-annotations for user-defined messaging annotations.
In addition, the user-defined annotations can have the same attributes (`inputChannel`, `@Poller`, `autoStartup`, and others).
For more information, see xref:configuration/annotations.adoc[Annotation Support].

[[x4.0-general]]
== General Changes

This section describes general changes from version 3.0 to version 4.0.

[[requires-spring-framework-4-0]]
=== Requires Spring Framework 4.0

We moved the core messaging abstractions (`Message`, `MessageChannel`, and others) to the Spring Framework `spring-messaging` module.
Developers who reference these classes directly in their code need to make changes, as described in the first section of the https://github.com/spring-projects/spring-integration/wiki/Spring-Integration-3.0-to-4.0-Migration-Guide[3.0 to 4.0 Migration Guide].

[[x4.0-xpath-header-enricher-header-type]]
=== Header Type for XPath Header Enricher

We introduced the `header-type` attribute for the `header` child element of the `<int-xml:xpath-header-enricher>`.
This attribute provides the target type for the header value (to which the result of the XPath expression evaluation is converted).
For more information see xref:xml/xpath-header-enricher.adoc[XPath Header Enricher].

[[x4.0-object-to-json-transformer-result-type]]
=== Object To JSON Transformer: Node Result

We introduced the `result-type` attribute for the `<int:object-to-json-transformer>`.
This attribute provides the target type for the result of mapping an object to JSON.
It supports `STRING` (the default) and `NODE`.
For more information see xref:transformer.adoc#transformer-xpath-spel-function[Since version 3.0, Spring Integration also provides a built-in `#xpath` SpEL function for use in expressions.].

[[x4.0-jms-header-mapping]]
=== JMS Header Mapping

The `DefaultJmsHeaderMapper` now maps an incoming `JMSPriority` header to the Spring Integration `priority` header.
Previously, `priority` was only considered for outbound messages.
For more information, see xref:changes-3.0-4.0.adoc#x4.0-jms-header-mapping[Mapping Message Headers to and from JMS Message].

[[x4.0-jms-ob]]
=== JMS Outbound Channel Adapter

The JMS outbound channel adapter now supports the `session-transacted` attribute (default: `false`).
Previously, you had to inject a customized `JmsTemplate` to use transactions.
See xref:changes-3.0-4.0.adoc#x4.0-jms-ob[Outbound Channel Adapter].

[[x4.0-jms-ib]]
=== JMS Inbound Channel Adapter

The JMS inbound channel adapter now supports the `session-transacted` attribute (default: `false`).
Previously, you had to inject a customized `JmsTemplate` to use transactions.
The adapter allowed 'transacted' in the `acknowledgeMode`, which was incorrect and didn't work.
This value is no longer allowed.
See xref:changes-3.0-4.0.adoc#x4.0-jms-ib[Inbound Channel Adapter].

[[x4.0-datatype-channel]]
=== Datatype Channels

You can now specify a `MessageConverter` to be used when converting (if necessary) payloads to one of the accepted `datatype` instances in a Datatype channel.
For more information, see xref:channel/configuration.adoc#channel-datatype-channel[Datatype Channel Configuration].

[[x4.0-retry-config]]
=== Simpler Retry Advice Configuration

We added simplified namespace support to configure a `RequestHandlerRetryAdvice`.
For more information, see xref:handler-advice/classes.adoc#retry-config[Configuring the Retry Advice].

[[x4.0-release-strategy-group-timeout]]
=== Correlation Endpoint: Time-based Release Strategy

We added the mutually exclusive `group-timeout` and `group-timeout-expression` attributes to `<int:aggregator>` and `<int:resequencer>`.
These attributes allow forced completion of a partial `MessageGroup`, provided the `ReleaseStrategy` does not release a group and no further messages arrive within the time specified.
For more information, see xref:aggregator.adoc#aggregator-xml[Configuring an Aggregator with XML].

[[x4.0-redis-metadata]]
=== Redis Metadata Store

The `RedisMetadataStore` now implements `ConcurrentMetadataStore`, letting it be used, for example, in an `AbstractPersistentAcceptOnceFileListFilter` implementation in a multiple application instance or server environment.
For more information, see xref:redis.adoc#redis-metadata-store[Redis Metadata Store], xref:file/reading.adoc[Reading Files], xref:ftp/inbound.adoc[FTP Inbound Channel Adapter], and xref:sftp/inbound.adoc[SFTP Inbound Channel Adapter].

[[x4.0-jdbc-cs]]
=== `JdbcChannelMessageStore` and `PriorityChannel`

T`JdbcChannelMessageStore` now implements `PriorityCapableChannelMessageStore`, letting it be used as a `message-store` reference for `priority-queue` instances.
For more information, see xref:jdbc/message-store.adoc#jdbc-message-store-channels[Backing Message Channels].

[[x4.0-amqp]]
=== AMQP Endpoints Delivery Mode

Spring AMQP, by default, creates persistent messages on the broker.
You can override this behavior by setting the `amqp_deliveryMode` header or customizing the mappers.
We added a convenient `default-delivery-mode` attribute to the adapters to provide easier configuration of this important setting.
For more information, see xref:amqp/outbound-channel-adapter.adoc[Outbound Channel Adapter] and xref:amqp/outbound-gateway.adoc[Outbound Gateway].

[[x4.0-ftp]]
=== FTP Timeouts

The `DefaultFtpSessionFactory` now exposes the `connectTimeout`, `defaultTimeout`, and `dataTimeout` properties, avoiding the need to subclass the factory to set these common properties.
The `postProcess*` methods are still available for more advanced configuration.
See xref:ftp/session-factory.adoc[FTP Session Factory] for more information.

[[x4.0-twitter-status-updating]]
=== Twitter: `StatusUpdatingMessageHandler`

The `StatusUpdatingMessageHandler` (`<int-twitter:outbound-channel-adapter>`) now supports the `tweet-data-expression` attribute to build a `org.springframework.social.twitter.api.TweetData` object for updating the timeline status.
This feature allows, for example, attaching an image.
See https://github.com/spring-projects/spring-integration-extensions/tree/main/spring-integration-social-twitter[Spring Integration Social Twitter] for more information.

[[x4.0-jpa-id-expression]]
=== JPA Retrieving Gateway: `id-expression`

We introduced the `id-expression` attribute for `<int-jpa:retrieving-outbound-gateway>` to perform `EntityManager.find(Class entityClass, Object primaryKey)`.
See xref:jpa/outbound-gateways.adoc#jpa-retrieving-outbound-gateway[Retrieving Outbound Gateway] for more information.

[[x4.0-tcp-deserializer-events]]
=== TCP Deserialization Events

When one of the standard deserializers encounters a problem decoding the input stream to a message, it now emits a `TcpDeserializationExceptionEvent`, letting applications examine the data at the point at which the exception occurred.
See xref:changes-4.1-4.2.adoc#x4.2-tcp-events[TCP Connection Events] for more information.

[[x4.0-bean-messaging-annotations]]
=== Messaging Annotations on `@Bean` Definitions

You can now configure messaging annotations (`@ServiceActivator`, `@Router`, `@InboundChannelAdapter`, and others) on `@Bean` definitions in `@Configuration` classes.
For more information, see xref:configuration/annotations.adoc[Annotation Support].
