Chapter 18. Custom Interceptors

It is possible to add custom interceptors to Red Hat Data Grid, both declaratively and programatically. Custom interceptors are a way of extending Red Hat Data Grid by being able to influence or respond to any modifications to cache. Example of such modifications are: elements are added/removed/updated or transactions are committed. For a detailed list refer to CommandInterceptor API.

18.1. Adding custom interceptors declaratively

Custom interceptors can be added on a per named cache basis. This is because each named cache have its own interceptor stack. Following xml snippet depicts the ways in which a custom interceptor can be added.

   <local-cache name="cacheWithCustomInterceptors">
      <!--
      Define custom interceptors.  All custom interceptors need to extend org.jboss.cache.interceptors.base.CommandInterceptor
      -->
      <custom-interceptors>
         <interceptor position="FIRST" class="com.mycompany.CustomInterceptor1">
               <property name="attributeOne">value1</property>
               <property name="attributeTwo">value2</property>
         </interceptor>
         <interceptor position="LAST" class="com.mycompany.CustomInterceptor2"/>
         <interceptor index="3" class="com.mycompany.CustomInterceptor1"/>
         <interceptor before="org.infinispanpan.interceptors.CallInterceptor" class="com.mycompany.CustomInterceptor2"/>
         <interceptor after="org.infinispanpan.interceptors.CallInterceptor" class="com.mycompany.CustomInterceptor1"/>
      </custom-interceptors>
   </local-cache>

18.2. Adding custom interceptors programatically

In order to do that one needs to obtain a reference to the AdvancedCache . This can be done ass follows:

CacheManager cm = getCacheManager();//magic
Cache aCache = cm.getCache("aName");
AdvancedCache advCache = aCache.getAdvancedCache();

Then one of the addInterceptor() methods should be used to add the actual interceptor. For further documentation refer to AdvancedCache javadoc.

18.3. Custom interceptor design

When writing a custom interceptor, you need to abide by the following rules.

+ * Custom interceptors must extend BaseCustomInterceptor * Custom interceptors must declare a public, empty constructor to enable construction. * Custom interceptors will have setters for any property defined through property tags used in the XML configuration.