/*
* Copyright 2002-2015 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.integration.annotation;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
* Indicates that an interface method is capable of mapping its parameters
* to a message or message payload. These method-level annotations are detected
* by the {@link org.springframework.integration.gateway.GatewayProxyFactoryBean}
* where the annotation attributes can override the default channel settings.
*
* <p>A method annotated with @Gateway may accept a single non-annotated
* parameter of type {@link org.springframework.messaging.Message}
* or of the intended Message payload type. Method parameters may be mapped
* to individual Message header values by using the
* {@link org.springframework.messaging.handler.annotation.Header @Header}
* parameter annotation. Alternatively, to pass the entire Message headers
* map, a Map-typed parameter may be annotated with
* {@link org.springframework.messaging.handler.annotation.Headers}.
*
* <p>Return values from the annotated method may be of any type. If the
* declared return value is not a Message, the reply Message's payload will be
* returned and any type conversion as supported by Spring's
* {@link org.springframework.beans.SimpleTypeConverter} will be applied to
* the return value if necessary.
*
* <p>Note: unlike @Publisher, this annotation is for exposing a
* Messaging Endpoint based on a Proxy for the marked interface method.
* The method invocation causes messaging interaction using an
* AOP Advice. Method parameters become the part of sent message (payload, headers).
* The method return value is the result (payload) of the messaging flow invoked by the
* Proxy.
*
* @author Mark Fisher
* @author Gary Russell
* @author Artem Bilan
*
* @see MessagingGateway
*/
@Target({ElementType.METHOD, ElementType.ANNOTATION_TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Inherited
@Documented
public @interface Gateway {
/**
* Specify the channel to which messages will be sent; overrides the encompassing
* gateway's default request channel.
* @return the channel name.
*/
String requestChannel() default "";
/**
* Specify the channel from which reply messages will be received; overrides the
* encompassing gateway's default reply channel.
* @return the channel name.
*/
String replyChannel() default "";
/**
* Specify the timeout (ms) when sending to the request channel - only applies if the
* send might block (such as a bounded {@code QueueChannel} that is currently full.
* Overrides the encompassing gatewsy's default request timeout.
* @return the timeout.
*/
long requestTimeout() default Long.MIN_VALUE;
/**
* Specify the time (ms) that the thread sending the request will wait for a reply.
* The timer starts when the thread returns to the gateway, not when the request
* message is sent. Overrides the encompassing gateway's default reply timeout.
* @return the timeout.
*/
long replyTimeout() default Long.MIN_VALUE;
/**
* Specify a SpEL expression to determine the payload of the request message.
* @return the expression.
*/
String payloadExpression() default "";
/**
* Specify additional headers that will be added to the request message.
* @return the headers.
*/
GatewayHeader[] headers() default {};
}