In order to know exactly how your application uses eXo JCR, it can be interesting to register all the JCR API accesses in order to easily create real life test scenario based on pure JCR calls and also to tune your eXo JCR to better fit your requirements.

In order to allow you to specify the configuration which part of eXo JCR needs to be monitored without applying any changes in your code and/or building anything, we choose to rely on the Load-time Weaving proposed by AspectJ.

To enable this feature, you will have to add in your classpath the following jar files:

You will also need to get aspectjweaver-1.6.8.jar from the main maven repository http://repo2.maven.org/maven2/org/aspectj/aspectjweaver. At this stage, to enable the statistics on the JCR API accesses, you will need to add the JVM parameter -javaagent:${pathto}/aspectjweaver-1.6.8.jar to your command line, for more details please refer to http://www.eclipse.org/aspectj/doc/released/devguide/ltw-configuration.html.

By default, the configuration will collect statistics on all the methods of the internal interfaces org.exoplatform.services.jcr.core.ExtendedSession and org.exoplatform.services.jcr.core.ExtendedNode, and the JCR API interface javax.jcr.Property. To add and/or remove some interfaces to monitor, you have two configuration files to change that are bundled into the jar exo.jcr.component.statistics-X.Y.Z.jar, which are conf/configuration.xml and META-INF/aop.xml.

The file content below is the content of conf/configuration.xml that you will need to modify to add and/or remove the full qualified name of the interfaces to monitor, into the list of parameter values of the init param called targetInterfaces.

<configuration xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.exoplatform.org/xml/ns/kernel_1_2.xsd http://www.exoplatform.org/xml/ns/kernel_1_2.xsd"

 xmlns="http://www.exoplatform.org/xml/ns/kernel_1_2.xsd">



 <component>

   <type>org.exoplatform.services.jcr.statistics.JCRAPIAspectConfig</type>

   <init-params>

     <values-param>

       <name>targetInterfaces</name>

       <value>org.exoplatform.services.jcr.core.ExtendedSession</value>

       <value>org.exoplatform.services.jcr.core.ExtendedNode</value>

       <value>javax.jcr.Property</value>

     </values-param>

   </init-params>

  </component>

</configuration>

The file content below is the content of META-INF/aop.xml that you will need to modify to add and/or remove the full qualified name of the interfaces to monitor, into the expression filter of the pointcut called JCRAPIPointcut. As you can see below, by default only JCR API calls from the exoplatform packages are took into account, don't hesistate to modify this filter to add your own package names.

<aspectj>

  <aspects>

    <concrete-aspect name="org.exoplatform.services.jcr.statistics.JCRAPIAspectImpl" extends="org.exoplatform.services.jcr.statistics.JCRAPIAspect">

      <pointcut name="JCRAPIPointcut"

        expression="(target(org.exoplatform.services.jcr.core.ExtendedSession) || target(org.exoplatform.services.jcr.core.ExtendedNode) || target(javax.jcr.Property)) &amp;&amp; call(public * *(..))" />

    </concrete-aspect>

  </aspects>

  <weaver options="-XnoInline">

    <include within="org.exoplatform..*" />

  </weaver>

</aspectj> 

The corresponding CSV files are of type Statistics${interface-name}-${creation-timestamp}.csv for more details about how the csv files are managed, please refer to the section dedicated to the statistics manager.

The format of each column header is ${method-alias}-${metric-alias}. The method alias will be of type ${method-name}(list of parameter types separeted by ; to be compatible with the CSV format).

The metric alias are described in the statistics manager section.

The name of the category of statistics corresponding to these statistics is the simple name of the monitored interface (e.g. ExtendedSession for org.exoplatform.services.jcr.core.ExtendedSession), this name is mostly needed to access to the statistics through JMX.

Please note that this feature will affect the performances of eXo JCR so it must be used with caution.