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<title>How To use the Timer MBean</title><link rel="stylesheet" href="styles.css" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/styles.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets Vimages/callouts/"><link rel="home" href="index.html" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/index.html" title="JBoss 3.0 Documentation"><link rel="up" href="ch13.html" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/ch13.html" title="Chapter 13. HOWTO"><link rel="previous" href="ch13s39.html" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/ch13s39.html" title="JMX Connector Description and HowTo"><link rel="next" href="ch13s58.html" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/ch13s58.html" title="How To use the Timer MBean and Scheduler Service on JBoss 3"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><table border="0" cellpadding="0" cellspacing="0" height="65"><tr height="65"><td rowspan="2"><img src="jboss.gif" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/jboss.gif" border="0"></td><td rowspan="2" background="gbar.gif" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/gbar.gif" width="100%" align="right" valign="top"><a href="index.html" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/index.html"><img src="doc.gif" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/doc.gif" border="0"></a><a href="ch13.html" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/ch13.html"><img src="toc.gif" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/toc.gif" border="0"></a><a href="ch13s39.html" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/ch13s39.html"><img src="prev.gif" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/prev.gif" border="0"></a><a href="ch13s58.html" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/ch13s58.html"><img src="next.gif" tppabs="http://www.huihoo.org/jboss/online_manual/3.0/next.gif" border="0"></a></td></tr><tr></tr></table><div class="section"><a name="d0e10064"></a><div class="titlepage"><div><h2 class="title" style="clear: both"><a name="d0e10064"></a>How To use the Timer MBean</h2></div></div><p>Author:
<span class="author">Andreas Schaefer</span>
<tt><<a href="mailto:andreas.schaefer@madplanet.com">andreas.schaefer@madplanet.com</a>></tt>
</p><div class="section"><a name="d0e10078"></a><div class="titlepage"><div><h3 class="title"><a name="d0e10078"></a>Introduction</h3></div></div><p>
As part of the JMX specification each JMX compliant server must provide a timer service to let
the users being notified at a certain time, in a certain interval and/or number of occurrences.
Therefore you can check for mails, check if some change on target (auto deployer) or notify the
client for a date.
</p></div><div class="section"><a name="d0e10083"></a><div class="titlepage"><div><h3 class="title"><a name="d0e10083"></a>Preparation</h3></div></div><div class="itemizedlist"><ul><li><p><a name="d0e10087"></a>
First you have to add the timer service into the jboss.jcml therefore that the timer service
is loaded, registered at the JMX server and the initialized and started (done by JBoss's
Main.java class). This mbean tag looks like this:
<pre class="programlisting">
<mbean code="javax.management.timer.Timer" name="DefaultDomain:service=timer"/>
</pre>
Keep in mind that there will be no notification about the startup. To check use the JMX
HTML-Adaptor on port 8082 by default. The timer is loaded from the jmxri.jar file in /lib
directory.
</p></li><li><p><a name="d0e10093"></a>
If you are not using JBoss then to the following (which means that you want to use a timer
outside of JBoss (maybe on the client or administration side):
<div class="orderedlist"><ol type="1"><li><p><a name="d0e10097"></a>
Create a MBeanServer
<pre class="programlisting">
MBeanServer lServer = MBeanServerFactory.createMBeanServer();
</pre>
</p></li><li><p><a name="d0e10103"></a>
Load and register the Timer MBean
<pre class="programlisting">
ObjectInstance lTimer = lServer.createMBean(
"javax.management.timer.Timer",
new ObjectName( "DefaultDomain", "service", "timer" )
);
</pre>
</p></li><li><p><a name="d0e10109"></a>
Initialize and start the timer service
<pre class="programlisting">
lServer.invoke(
lTimer.getObjectName(),
"start",
new Object[] {},
new String[] {}
);
</pre>
</p></li></ol></div>
</p></li><li><p><a name="d0e10116"></a>Next step is to get the MBeanServer within your object to work with the timer.</p><p>
This is quite simple if your are in a MBean registered to the same JMX server because
then you get it when you overwrite preRegister() method.
When you are in the same JVM as the JMX server (in JBoss is any instance running
within JBoss like EJBs or other classes). Then you can obtain the MBeanServer through:
</p><pre class="programlisting">
MBeanServer lServer =
(MBeanServer) MBeanServerFactory.findMBeanServer( null ).get( 0 );
</pre><p>
For the rest it is a little bit more complicated. In a Java client you can use JBoss RMI
connector which will be released as separat package till mid December 2000. Then you
connect to a MBeanServer through the RemoteMBeanServer interface which is more or less
the same.
</p></li><li><p><a name="d0e10125"></a>
We are nearly there: now we need the reference to the timer service to work on it (lServer
can be either of type MBeanServer or RemoteMBeanServer):
</p><pre class="programlisting">
Set lBeans = lServer.queryMBeans(
new ObjectName(
"DefaultDomain",
"service",
"timer"
),
null
);
if( !lBeans.isEmpty() ) { // Should be the first and only element
ObjectInstance lTimer = (ObjectInstance) lBeans.iterator().next();
</pre></li><li><p><a name="d0e10130"></a>
Let's go to work with the timer. Because the timer sends a Notification Event to the
listeners we have to register first:
</p><pre class="programlisting">
lServer.addNotificationListener(
lTimer.getObjectName(),
new Listener(),
// No filter
null,
// No object handback necessary
null
);
</pre></li><li><p><a name="d0e10135"></a>
The Listener (in this case) is an inner class implementing the NotificationListener
interface:
</p><pre class="programlisting">
public class Listener
implements NotificationListener
{
public void handleNotification(
Notification pNotification,
Object pHandback
) {
// Here to whatever you want or call a method
// in the outer class
System.out.println( "You got a Notification: " + pNotification );
}
}
</pre></li><li><p><a name="d0e10140"></a>
Finally we are ready to rock and roll. We set a timer event for a particular time and at
this time the Listener.handleNotification() get called.
</p><pre class="programlisting">
Date lNext = new Date( new Date().getTime() + Timer.ONE_MINUTE );
Integer lOneMinuteTimer = (Integer) lServer.invoke(
lTimer.getObjectName(),
"addNotification",
new Object[] {
"IDoNotKnowWhatTypeIs",
"I call you with this timer once",
// No user object
null,
// I one minute from now
lNext,
},
new String[] {
"".getClass().getName(),
"".getClass().getName(),
"java.lang.Object",
Date.class.getName()
}
);
</pre></li><li><p><a name="d0e10145"></a>
A timer notification after an Hour from now repeating every minute for ten times.
</p><pre class="programlisting">
Date lNext = new Date( new Date().getTime() + Timer.ONE_HOUR );
Integer lOneHourTimer = (Integer) lServer.invoke(
lTimer.getObjectName(),
"addNotification",
new Object[] {
"IDoNotKnowWhatTypeIs",
"I call you with this timer once",
// No user object
null,
// In one minute from now
lNext,
new Long( Timer.ONE_MINUTE ),
new Long( 10 )
},
new String[] {
"".getClass().getName(),
"".getClass().getName(),
"java.lang.Object",
Date.class.getName(),
Long.TYPE.getName(),
Long.TYPE.getName()
}
);
</pre></li><li><p><a name="d0e10150"></a>If you want to get rid of the second timer then do:</p><pre class="programlisting">
lServer.invoke(
lTimer.getObjectName(),
"removeNotification",
new Object[] {
// You could also use the type: "IDoNotKnowWhatTypeIs"
lOneHourTimer
},
new String[] {
// If you remove by type: String.getClass().getName()
Integer.TYPE.getName()
}
);
</pre></li></ul></div><p>
Now the rest is quite simple. Have a look at the javax.management.timer.Timer class description and
use the MBeanServer.invoke() method style.
</p><p>
Attention: When you have basic data type in the method signature then
you have to use its wrapper class TYPE variable to get its class instead of using just "long" etc.
</p><p>
If anything is wrong or not correct please contact me at andreas.schaefer@madplanet.com. Also if
you want to know more in detail or have a request for further infos.
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