Invoking Async method call using Future object Using Spring Integration

The next example will demonstrate an async method call inside the Spring container.

Why do we need async method calls?

In some cases we don’t really know if replay is expected or when a result supposed to be delivered back.

Traditional way In the Java EE world of handling async calls is using Queue/Topic.

We could do the same in Spring but if needed a simple async invocation, you could do it easily by following the next steps:

1. Declare Asynchronous Gateway:

<bean id="executionLogicImpl"
 class="com.test.components.execution_gateway.ExecutionLogicImpl"
 abstract="false" lazy-init="default" autowire="default">
 </bean>

2. declare interface method with return type – Future(Java 5+):

More information on Future object: http://docs.oracle.com/javase/1.5.0/docs/api/java/util/concurrent/Future.html

public interface ExecutionLogic
{

 public Future<String> doSomeExecutionLogic(String message);

}

* As soon as the GatewayProxyFactoryBean notice a return type Future it will switch the method into an async mode by having AsyncTaskExecutor

3. We will create a job channel which will collect all requests and send them asynchronously to another class(ExecutionLogicImpl) in order to process them(some random business logic):

<int:channel id="job1Channel" />

<int:service-activator input-channel="job1Channel" ref="executionLogicImpl" method="doSomeExecutionLogic" />

The class ExecutionLogicImpl:

public class ExecutionLogicImpl
{
 public String doSomeExecutionLogic(String msg)
 {
 try
 {
 System.out.println("doing long work on message="+msg);
 Thread.sleep(8000);

}
 catch (InterruptedException e)
 {
 // TODO Auto-generated catch block
 e.printStackTrace();
 }
 return msg + "_completed";

}

}

Test class:

import com.test.components.execution_gateway.ExecutionLogic;

public class testExeceution

{

...
ExecutionLogic executionLogic;
public String sendMsgToExecutionQueue(String msg)
 {
 Future<String> processedMessage = executionLogic.doSomeExecutionLogic(msg);

String finalResult = "";
 try
 {
 finalResult = " " + processedMessage.get(TIMEOUT, TimeUnit.SECONDS);
 return "1 final result: " + finalResult; // + " " + response;
 }
 catch (ExecutionException e)
 {
 return "1 final result: " + e + finalResult;// + " " + response;
 }
 catch (TimeoutException tex)
 {
 return "1 final result: " + tex + finalResult; // + " " + response;
 }
 catch (Exception ex)
 {
 return "1 final result: " + ex + finalResult;// + " " + response;
 }

}
...
}

* You can enable timeout using the Future object for cases a response will never be returned.

So what’s happening here? We sending input to be executed asynchronously. The sender is waiting for response (asynchronously) as soon as the request finish it’s processing a result will be sent back to the sender.

Idan.

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