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<h2>Purpose</h2>
<p>The purpose of this aspect is to report arbitrary method execution response time to a JMX server.<br />
It is easily configurable to gather the metrics on a per class, package, application, etc basis and thus report averages metrics as well.</p>

<p>This aspect has been demonstrated during JavaOne 2004 in the &quot;AOP in J2EE environments with AspectWerkz&quot; session.<br />
<a href="http://aspectwerkz.codehaus.org/downloads/papers/JavaOne2004-TS1391-J2EEAOP.pdf">Download the JavaOne 2004 slides</a>.</p>

<h2>Usage</h2>
<p>In order to be able to use this aspect, you need to declare it in your <strong>META-INF/aop.xml</strong> file and bind the advice named <strong>&quot;monitor&quot;</strong> of type <strong>&quot;around&quot;</strong> to any method execution pointcuts (actually it can work for any pointcut type if you want to).</p>

<p>One JMX mbean will be created per target method/constructor/field signature by default. See the next section for more configuration about the aspect parameter <strong>&quot;granularity&quot;</strong>.</p>

<p>The mbeans will be registered <em>lazyly</em> in the default (local) JMX server. For use with BEA WebLogic Server 6, 7 and 8 and for other schemes, see the next section about the aspect parameter <strong>&quot;mbeanServer&quot;</strong>.</p>

<p>Here is a sample <em>META-INF/aop.xml</em> file:</p>
<table class="wysiwyg-macro" data-macro-name="code" data-macro-default-parameter="xml" style="background-image: url(/plugins/servlet/confluence/placeholder/macro-heading?definition=e2NvZGU6eG1sfQ&amp;locale=en_GB&amp;version=2); background-repeat: no-repeat;" data-macro-body-type="PLAIN_TEXT"><tr><td class="wysiwyg-macro-body"><pre>
&lt;!DOCTYPE aspectwerkz PUBLIC
    "-//AspectWerkz//DTD//EN"
    "http://aspectwerkz.codehaus.org/dtd/aspectwerkz.dtd">
&lt;aspectwerkz>
    &lt;system id="aware-jmx">
        &lt;!-- make use of defaults granularity and server -->
        &lt;aspect class="org.codehaus.aware.jmx.ResponseTimeAspect">
            &lt;advice name="monitor" type="around"
                    bind-to="execution(!static * test.jmx.ResponseTimeObject.*(..)) AND !execution(* *..*.freeze(..))"/>
        &lt;/aspect>
  &lt;/system>
&lt;/aspectwerkz>
</pre></td></tr></table>

<h2>Reporting response time averages</h2>
<p>To change the granularity of the reported metrics, which defaults to <em>one mbean per target method/constructor/field signature</em> you need to use the <em>aspect parameter</em> <strong>&quot;granularity&quot;</strong>.</p>

<p>This parameter will specify a class that implements the <em>org.codehaus.aware.jmx.ResponseTimeAspect.IGranularity</em> interface below:</p>
<table class="wysiwyg-macro" data-macro-name="code" data-macro-default-parameter="java" style="background-image: url(/plugins/servlet/confluence/placeholder/macro-heading?definition=e2NvZGU6amF2YX0&amp;locale=en_GB&amp;version=2); background-repeat: no-repeat;" data-macro-body-type="PLAIN_TEXT"><tr><td class="wysiwyg-macro-body"><pre>
public class ResponseTimeAspect {
    /**
     * Granularity interface to determine which mbean to update given a specific joinpoint signature.
     *
     */
    public static interface IGranularity {
        /**
         * Compute a suitable key given a signature. The mbeans will be register on a per key basis, and it is thus
         * advised to have suitable hashcode(), equals() and toString() implementation for it.
         *
         * @param signature
         * @return
         */
        public Object getKeyFor(Signature signature);
    }
}
</pre></td></tr></table>

<p>AWare provides an implementation which is able to compute a global average. Here is how it has been written. You can refer to AspectWerkz documentation about the <em>org.codehaus.aspectwerkz.joinpoint.Signature</em> interface to write your own:</p>
<table class="wysiwyg-macro" data-macro-name="code" data-macro-default-parameter="java" style="background-image: url(/plugins/servlet/confluence/placeholder/macro-heading?definition=e2NvZGU6amF2YX0&amp;locale=en_GB&amp;version=2); background-repeat: no-repeat;" data-macro-body-type="PLAIN_TEXT"><tr><td class="wysiwyg-macro-body"><pre>
public class AverageGranularity implements IGranularity {
    public Object getKeyFor(Signature signature) {
        // to compute a global average, just always return the same value
        return "Average";
    }
}
</pre></td></tr></table>
<p>This class is provided in AWare as org.codehaus.aware.jmx.ResponseTimeAspect.AverageGranularity. Since it is a static inner class, we will have to use it under the name &quot;org.codehaus.aware.jmx.ResponseTimeAspect$AverageGranularity&quot; (with a <strong>$</strong> sign) :</p>

<p>To use your custom granularity the <em>META-INF/aop.xml</em> file will look like the following. Note that we are using the ResponseTimeAspect twice, once with default granularity and once with average granularity, and thus we specify an aspect <strong>&quot;name&quot;</strong>.</p>
<table class="wysiwyg-macro" data-macro-name="code" data-macro-default-parameter="xml" style="background-image: url(/plugins/servlet/confluence/placeholder/macro-heading?definition=e2NvZGU6eG1sfQ&amp;locale=en_GB&amp;version=2); background-repeat: no-repeat;" data-macro-body-type="PLAIN_TEXT"><tr><td class="wysiwyg-macro-body"><pre>
&lt;!DOCTYPE aspectwerkz PUBLIC
    "-//AspectWerkz//DTD//EN"
    "http://aspectwerkz.codehaus.org/dtd/aspectwerkz.dtd">
&lt;aspectwerkz>
    &lt;system id="aware-jmx">
        &lt;!-- make use of defaults granularity and server -->
        &lt;aspect class="org.codehaus.aware.jmx.ResponseTimeAspect">
            &lt;advice name="monitor" type="around"
                    bind-to="execution(!static * test.jmx.ResponseTimeObject.*(..)) AND !execution(* *..*.freeze(..))"/>
        &lt;/aspect>
        &lt;!-- make use of custom granularity -->
        &lt;aspect class="org.codehaus.aware.jmx.ResponseTimeAspect" name="MyAverageResponseTimeAspect">
            &lt;param name="granularity" value="org.codehaus.aware.jmx.ResponseTimeAspect$AverageGranularity"/>
            &lt;advice name="monitor" type="around"
                    bind-to="execution(!static * test.jmx.ResponseTimeObject.*(..)) AND !execution(* *..*.freeze(..))"/>
        &lt;/aspect>
  &lt;/system>
&lt;/aspectwerkz>
</pre></td></tr></table>

<h2>Using a specific JMX mbean server</h2>

<p>The default AWare implementation is using the default JMX API to retrieve the local JMX server and register the mbeans:</p>
<table class="wysiwyg-macro" data-macro-name="code" data-macro-default-parameter="java" style="background-image: url(/plugins/servlet/confluence/placeholder/macro-heading?definition=e2NvZGU6amF2YX0&amp;locale=en_GB&amp;version=2); background-repeat: no-repeat;" data-macro-body-type="PLAIN_TEXT"><tr><td class="wysiwyg-macro-body"><pre>
public class JMXHelper {
    /**
     * Default driver interface using javax.management.MBeanServerFactory.
     * See MX4JAspect if using it with MX4J jmx server.
     *
     */
    public static class StandardMBeanServerDriver implements IMBeanServerDriver {
        public MBeanServer findMBeanServer() throws Throwable {
            return javax.management.MBeanServerFactory.createMBeanServer();
        }
    }
}
</pre></td></tr></table>

<p>This might not be convenient in your environment. For example in BEA WebLogic, you have several JMX server available when you are running in a cluster or in a managed server environment.</p>

<p>AWare allows you to use the mbean server you like.<br />
For such use the aspect parameter <strong>&quot;mbeanServer&quot;</strong> and specify a class that implements the <em>org.codehaus.aware.jmx.JMXHelper.IMBeanServerDriver</em> interface:</p>
<table class="wysiwyg-macro" data-macro-name="code" data-macro-default-parameter="java" style="background-image: url(/plugins/servlet/confluence/placeholder/macro-heading?definition=e2NvZGU6amF2YX0&amp;locale=en_GB&amp;version=2); background-repeat: no-repeat;" data-macro-body-type="PLAIN_TEXT"><tr><td class="wysiwyg-macro-body"><pre>
    public interface IMBeanServerDriver {
        public MBeanServer findMBeanServer() throws Throwable;
    }
</pre></td></tr></table>

<p>AWare provides a BEA Weblogic implementation of it thru <strong>org.codehaus.aware.jmx.JMXHelper.WebLogicMBeanServerDriver</strong>.</p>

<p>To use it, the <em>META-INF/aop.xml</em> will looks like:</p>
<table class="wysiwyg-macro" data-macro-name="code" data-macro-default-parameter="xml" style="background-image: url(/plugins/servlet/confluence/placeholder/macro-heading?definition=e2NvZGU6eG1sfQ&amp;locale=en_GB&amp;version=2); background-repeat: no-repeat;" data-macro-body-type="PLAIN_TEXT"><tr><td class="wysiwyg-macro-body"><pre>
&lt;aspectwerkz>
    &lt;system id="aware-jmx">
        &lt;!-- make use of defaults granularity and use WebLogic mbean server custom lookup -->
        &lt;aspect class="org.codehaus.aware.jmx.ResponseTimeAspect">
            &lt;param name="mbeanServer" value="org.codehaus.aware.jmx.JMXHelper$WebLogicMBeanServerDriver"/>
            &lt;advice name="monitor" type="around"
                    bind-to="execution(!static * test.jmx.ResponseTimeObject.*(..)) AND !execution(* *..*.freeze(..))"/>
        &lt;/aspect>
  &lt;/system>
&lt;/aspectwerkz>
</pre></td></tr></table>