Stacking Interceptors
Further to my earlier posts about Mule Interceptors and Envelope Interceptors, one quick point about having more than one interceptor in your Mule config is merited.
Mule supports the concept of an interceptor stack which is nothing more than a list of interceptors. This is useful since you can avoid having to include all the interceptors in every service – just refer to the stack. Since interceptors are the sort of things you’d use in multiple locations, using an interceptor stack can greatly simplify things.
Instead of doing this:
<component> <custom-interceptor class="com.ricston.tests.HelloInterceptor"/> <custom-interceptor class="com.ricston.tests.SecondInterceptor"/> <prototype-object class="com.ricston.tests.SimpleBridge"/> </component> <component> <custom-interceptor class="com.ricston.tests.HelloInterceptor"/> <custom-interceptor class="com.ricston.tests.SecondInterceptor"/> <prototype-object class="com.ricston.tests.AnotherService"/> </component>
you can do this:
<interceptor-stack name="customIntercepting"> <custom-interceptor class="com.ricston.tests.HelloInterceptor"/> <custom-interceptor class="com.ricston.tests.SecondInterceptor"/> </interceptor-stack> <model> <!-- Other services --> <service name="Bridge"> <!-- Inbound router collection left out in this example --> <component> <interceptor-stack ref="customIntercepting"/> <prototype-object class="com.ricston.tests.SimpleBridge"/> </component> </service> <service name="Another"> <!-- Inbound router collection left out in this example --> <component> <interceptor-stack ref="customIntercepting"/> <prototype-object class="com.ricston.tests.AnotherService"/> </component> </service>
Additionally, you can also declare an interceptor stack as well as an interceptor on a service. This is useful in cases when you want to add one more interceptor to the standard list in a few cases:
<!-- Other services --> <service name="Bridge"> <!-- Inbound router collection left out in this example --> <component> <interceptor-stack ref="customIntercepting"/> <logging-interceptor/> <prototype-object class="com.ricston.tests.SimpleBridge"/> </component> </service>
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Tags: interceptor-stacks, interceptors, stacks