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               <h1>@Asynchronous @PostConstruct</h1>
             </div>
           </div>
         </div>
         <div class="row">

             <div class="col-md-12">
                 <p>Placing <code>@Asynchronous</code> on the <code>@PostConstruct</code> of an EJB is not a supported part of Java EE, but this example shows a pattern which works just as well with little effort.</p>
 <p>The heart of this pattern is to:</p>
 <ul>
   <li>pass the construction "logic" to an <code>@Asynchronous</code> method via a <code>java.util.concurrent.Callable</code></li>
   <li>ensure the bean does not process invocations till construction is complete via an <code>@AroundInvoke</code> method on the bean and the <code>java.util.concurrent.Future</code></li>
 </ul>
 <p>Simple and effective. The result is a faster starting application that is still thread-safe.</p>
 <pre><code>package org.superbiz.asyncpost;

 import javax.annotation.PostConstruct;
 import javax.ejb.EJB;
 import javax.ejb.Lock;
 import javax.ejb.LockType;
 import javax.ejb.Singleton;
 import javax.interceptor.AroundInvoke;
 import javax.interceptor.InvocationContext;
 import java.util.concurrent.Callable;
 import java.util.concurrent.Future;

 import static java.util.concurrent.TimeUnit.SECONDS;

 @Singleton
 @Lock(LockType.READ)
 public class SlowStarter {

     @EJB
     private Executor executor;

     private Future construct;

     private String color;
     private String shape;

     @PostConstruct
     private void construct() throws Exception {
         construct = executor.submit(new Callable() {
             @Override
             public Object call() throws Exception {
                 Thread.sleep(SECONDS.toMillis(10));
                 SlowStarter.this.color = &quot;orange&quot;;
                 SlowStarter.this.shape = &quot;circle&quot;;
                 return null;
             }
         });
     }

     @AroundInvoke
     private Object guaranteeConstructionComplete(InvocationContext context) throws Exception {
         construct.get();
         return context.proceed();
     }

     public String getColor() {
         return color;
     }

     public String getShape() {
         return shape;
     }
 }
 </code></pre>
 <p>The <code>Executor</code> is a simple pattern, useful for many things, which exposes an interface functionaly equivalent to <code>java.util.concurrent.ExecutorService</code>, but with the underlying thread pool controlled by the container.</p>
 <pre><code>package org.superbiz.asyncpost;

 import javax.ejb.AsyncResult;
 import javax.ejb.Asynchronous;
 import javax.ejb.Lock;
 import javax.ejb.LockType;
 import javax.ejb.Singleton;
 import java.util.concurrent.Callable;
 import java.util.concurrent.Future;

 @Singleton
 @Lock(LockType.READ)
 public class Executor {

     @Asynchronous
     public &lt;T&gt; Future&lt;T&gt; submit(Callable&lt;T&gt; task) throws Exception {
         return new AsyncResult&lt;T&gt;(task.call());
     }

 }
 </code></pre>
 <p>Finally a test case shows the usefulness of <code>@AroundInvoke</code> call in our bean that calls <code>construct.get()</code></p>
 <pre><code>package org.superbiz.asyncpost;

 import junit.framework.Assert;
 import org.junit.Test;

 import javax.ejb.EJB;
 import javax.ejb.embeddable.EJBContainer;

 public class SlowStarterTest {

     @EJB
     private SlowStarter slowStarter;

     @Test
     public void test() throws Exception {

         // Start the Container
         EJBContainer.createEJBContainer().getContext().bind(&quot;inject&quot;, this);

         // Immediately access the fields initialized in the PostConstruct
         // This will fail without the @AroundInvoke call to construct.get()
         Assert.assertEquals(&quot;orange&quot;, slowStarter.getColor());
         Assert.assertEquals(&quot;circle&quot;, slowStarter.getShape());
     }
 }
 </code></pre>
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	<div class='page-header'>

	<h1>@Asynchronous @PostConstruct</h1>
	</div>
	</div>
	</div>
	<div class="row">

	<div class="col-md-12">
	<p>Placing <code>@Asynchronous</code> on the <code>@PostConstruct</code> of an EJB is not a supported part of Java EE, but this example shows a pattern which works just as well with little effort.</p>
	<p>The heart of this pattern is to:</p>
	<ul>
	<li>pass the construction "logic" to an <code>@Asynchronous</code> method via a <code>java.util.concurrent.Callable</code></li>
	<li>ensure the bean does not process invocations till construction is complete via an <code>@AroundInvoke</code> method on the bean and the <code>java.util.concurrent.Future</code></li>
	</ul>
	<p>Simple and effective. The result is a faster starting application that is still thread-safe.</p>
	<pre><code>package org.superbiz.asyncpost;

	import javax.annotation.PostConstruct;
	import javax.ejb.EJB;
	import javax.ejb.Lock;
	import javax.ejb.LockType;
	import javax.ejb.Singleton;
	import javax.interceptor.AroundInvoke;
	import javax.interceptor.InvocationContext;
	import java.util.concurrent.Callable;
	import java.util.concurrent.Future;

	import static java.util.concurrent.TimeUnit.SECONDS;

	@Singleton
	@Lock(LockType.READ)
	public class SlowStarter {

	@EJB
	private Executor executor;

	private Future construct;

	private String color;
	private String shape;

	@PostConstruct
	private void construct() throws Exception {
	construct = executor.submit(new Callable() {
	@Override
	public Object call() throws Exception {
	Thread.sleep(SECONDS.toMillis(10));
	SlowStarter.this.color = "orange";
	SlowStarter.this.shape = "circle";
	return null;
	}
	});
	}

	@AroundInvoke
	private Object guaranteeConstructionComplete(InvocationContext context) throws Exception {
	construct.get();
	return context.proceed();
	}

	public String getColor() {
	return color;
	}

	public String getShape() {
	return shape;
	}
	}
	</code></pre>
	<p>The <code>Executor</code> is a simple pattern, useful for many things, which exposes an interface functionaly equivalent to <code>java.util.concurrent.ExecutorService</code>, but with the underlying thread pool controlled by the container.</p>
	<pre><code>package org.superbiz.asyncpost;

	import javax.ejb.AsyncResult;
	import javax.ejb.Asynchronous;
	import javax.ejb.Lock;
	import javax.ejb.LockType;
	import javax.ejb.Singleton;
	import java.util.concurrent.Callable;
	import java.util.concurrent.Future;

	@Singleton
	@Lock(LockType.READ)
	public class Executor {

	@Asynchronous
	public <T> Future<T> submit(Callable<T> task) throws Exception {
	return new AsyncResult<T>(task.call());
	}

	}
	</code></pre>
	<p>Finally a test case shows the usefulness of <code>@AroundInvoke</code> call in our bean that calls <code>construct.get()</code></p>
	<pre><code>package org.superbiz.asyncpost;

	import junit.framework.Assert;
	import org.junit.Test;

	import javax.ejb.EJB;
	import javax.ejb.embeddable.EJBContainer;

	public class SlowStarterTest {

	@EJB
	private SlowStarter slowStarter;

	@Test
	public void test() throws Exception {

	// Start the Container
	EJBContainer.createEJBContainer().getContext().bind("inject", this);

	// Immediately access the fields initialized in the PostConstruct
	// This will fail without the @AroundInvoke call to construct.get()
	Assert.assertEquals("orange", slowStarter.getColor());
	Assert.assertEquals("circle", slowStarter.getShape());
	}
	}
	</code></pre>
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