org.springframework.integration.annotation

Annotation Type MessagingGateway

@Target(value=TYPE)
 @Retention(value=RUNTIME)
 @Documented
public @interface MessagingGateway

A stereotype annotation to provide an Integration Messaging Gateway Proxy (<gateway/>) as an abstraction over the messaging API. The target application's business logic may be completely unaware of the Spring Integration API, with the code interacting only via the interface.

Important: The IntegrationComponentScan annotation is required along with Configuration to scan interfaces annotated with MessagingGateway, because the standard ComponentScan ignores interfaces.

Since:

4.0

Author:

Artem Bilan, Gary Russell

See Also:

IntegrationComponentScan

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element and Description
String	asyncExecutor Provide a reference to an implementation of Executor to use for any of the interface methods that have a Future return type.
GatewayHeader[]	defaultHeaders Provides custom message headers.
String	defaultPayloadExpression An expression that will be used to generate the payload for all methods in the service interface unless explicitly overridden by a method declaration.
String	defaultReplyChannel Identifies the default channel the gateway proxy will subscribe to, to receive reply Messages, the payloads of which will be converted to the return type of the method signature.
String	defaultReplyTimeout Allows to specify how long this gateway will wait for the reply Message before returning.
String	defaultRequestChannel Identifies the default channel to which messages will be sent upon invocation of methods of the gateway proxy.
String	defaultRequestTimeout Provides the amount of time dispatcher would wait to send a Message.
String	errorChannel Identifies a channel that error messages will be sent to if a failure occurs in the gateway's proxy invocation.
String	mapper An MethodArgsMessageMapper to map the method arguments to a Message.
String	name The value may indicate a suggestion for a logical component name, to be turned into a Spring bean in case of an autodetected component.
boolean	proxyDefaultMethods Indicate if default methods on the interface should be proxied as well.

Element Detail

name

public abstract String name

The value may indicate a suggestion for a logical component name, to be turned into a Spring bean in case of an autodetected component.

Returns:

the suggested component name, if any

Default:

""

defaultRequestChannel

public abstract String defaultRequestChannel

Identifies the default channel to which messages will be sent upon invocation of methods of the gateway proxy.

Returns:

the suggested channel name, if any

Default:

""

defaultReplyChannel

public abstract String defaultReplyChannel

Identifies the default channel the gateway proxy will subscribe to, to receive reply Messages, the payloads of which will be converted to the return type of the method signature.

Returns:

the suggested channel name, if any

Default:

""

errorChannel

public abstract String errorChannel

Identifies a channel that error messages will be sent to if a failure occurs in the gateway's proxy invocation. If no errorChannel reference is provided, the gateway will propagate Exceptions to the caller. To completely suppress Exceptions, provide a reference to the nullChannel here.

Returns:

the suggested channel name, if any

Default:

""

defaultRequestTimeout

public abstract String defaultRequestTimeout

Provides the amount of time dispatcher would wait to send a Message. This timeout would only apply if there is a potential to block in the send call. For example if this gateway is hooked up to a QueueChannel. Value is specified in milliseconds; it can be a simple long value or a SpEL expression; array variable #args is available.

Returns:

the suggested timeout in milliseconds, if any

Default:

"-9223372036854775808"

defaultReplyTimeout

public abstract String defaultReplyTimeout

Allows to specify how long this gateway will wait for the reply Message before returning. By default it will wait indefinitely. null is returned if the gateway times out. Value is specified in milliseconds; it can be a simple long value or a SpEL expression; array variable #args is available.

Returns:

the suggested timeout in milliseconds, if any

Default:

"-9223372036854775808"

asyncExecutor

public abstract String asyncExecutor

Provide a reference to an implementation of Executor to use for any of the interface methods that have a Future return type. This Executor will only be used for those async methods; the sync methods will be invoked in the caller's thread. Use AnnotationConstants.NULL to specify no async executor - for example if your downstream flow returns a Future.

Returns:

the suggested executor bean name, if any

Default:

""

defaultPayloadExpression

public abstract String defaultPayloadExpression

An expression that will be used to generate the payload for all methods in the service interface unless explicitly overridden by a method declaration. Variables include #args, #methodName, #methodString and #methodObject; a bean resolver is also available, enabling expressions like @someBean(#args).

Returns:

the suggested payload expression, if any

Default:

""

defaultHeaders

public abstract GatewayHeader[] defaultHeaders

Provides custom message headers. These default headers are created for all methods on the service-interface (unless overridden by a specific method).

Returns:

the suggested payload expression, if any

Default:

{}

mapper

public abstract String mapper

An MethodArgsMessageMapper to map the method arguments to a Message. When this is provided, no payload-expressions or headers are allowed; the custom mapper is responsible for creating the message.

Returns:

the suggested mapper bean name, if any

Default:

""

proxyDefaultMethods

public abstract boolean proxyDefaultMethods

Indicate if default methods on the interface should be proxied as well. If an explicit Gateway annotation is present on method it is proxied independently of this option. Note: default methods in JDK classes (such as Function) can be proxied, but cannot be invoked via MethodHandle by an internal Java security restriction for MethodHandle.Lookup.

Returns:

the boolean flag to proxy default methods or invoke via MethodHandle.

Since:

5.3

Default:

false