What filter chain includes in architecture of Struts 2x framework ?

The filter chain includes : 

ActionContextCleanUp filter

• This filter is optional and it is useful when integration has to be done with other technologies like SiteMash Plugin.

FilterDispatcher

• Next, the FilterDispatch is called which in turn uses the ActionMapper to determine weather to invoke an Action.
• If the action is required to be invoked, FilterDispatcher delegates the control to ActionProxy.

ActionProxy

• The ActionProxy takes the help from Configuration Files manager, which is initialized from the struts.xml.
• Then the ActionProxy creates an ActionInvocation, which implements the command pattern.

 

• The ActionInvocation process invokes the Interceptors (if configured) and then invokes the action.
• The the ActionInvocation looks for proper result.
• Then the result is executed, which involves the rendering of JSP or templates.

• Then the Interceptors are executed again in reverse order.
• Finally the response returned through the filters configured in web.xml file.

• If the ActionContextCleanUp filter is configured,
• The FilterDispatcher does not clean the ThreadLocal ActionContext.
  

• If the ActionContextCleanUp filter is not present then,
• The FilterDispatcher will cleanup all the ThreadLocals present.