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https://issues.apache.org/jira/browse/CLK-598?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12804243#action_12804243
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Bob Schellink commented on CLK-598:
-----------------------------------

Wonder if this functionality could be extended to a Control as well. In 
ClickClick I needed something similar: the ability to "intercept" certain 
events to add Ajax functionality to controls. Currently this is solved through 
a custom EventDispatcher that can fire listeners beforeOnProcess and 
beforeResponse. However the idea of an interceptor is semantically more correct 
than a listener for this scenario.

One issue with a ControlInterceptor is that we don't have full control over the 
control lifecycle. For example, controls are created and added by the 
developer, not by the framework so we won't be able to intercept all events 
such as onInit. However the more interesting interception points are 
beforeOnProcess and beforeOnResponse.

> Add Page Interceptor facility
> -----------------------------
>
>                 Key: CLK-598
>                 URL: https://issues.apache.org/jira/browse/CLK-598
>             Project: Click
>          Issue Type: New Feature
>          Components: core
>            Reporter: Malcolm Edgar
>             Fix For: 2.2.0
>
>
> Provide an application page interceptor /  listener facility into Click.  The 
> concept is to provide an extension point for code which can listener to key 
> page events and also interrupt normal page processing flow.
> Using this code which tends to be incorporated into Page superclasses can be 
> refactored into listener classes which can be reused in applications. This 
> approach supports Page design by composition, rather than through inheritance.
> Page listeners could be used for:
> * enforcing an application wide security polity, rather than using the 
> Page#onSecurityCheck() method
> * dependency injection, see CLK-581
> * support page performance profiling and logging
> The listener interface would be:
> public interface PageInterceptor {
>        boolean pageCreate(Class<? extends Page> pageClass, Context context);
>        boolean postCreate(Page page);
>        boolean preResponse(Page page);
>        void postDestroy(Page page);
> }
>  
> Application page interceptor  classes would be defined in the click.xml 
> configuration file. Applications could defined multiple interceptor which 
> would be executed sequentially in the order in which there are defined.  
> Lnterceptor could have a scope /  lifecycle of request (where by new 
> instances are created for each page request, and are threadsafe), or 
> application (where by a single instance is created and used for all page 
> requests).  interceptor can also be configured to have properties which are 
> set after creation.  This scope rules equates to Spring prototype and 
> singleton scopes.
> An example configuration is provided below:
>     <page-interceptor classname="com.mycorp.listener.ProfilingInterceptor"/>
>     <page-interceptor classname="com.mycorp.listener.SecurityInterceptor" 
> scope="application">
>         <property name="notAthenticatedPath" value="/login.htm"/>
>         <property name="notAuthorizedPath" value="/not-authorized.htm"/>
>     </page-interceptor >
>    

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