Securing services

[Moritz Gmelin]

Hi,

Securing page access with an access controller injected as a  
dispatcher in the render cycle is well described in the T5 wiki. But  
How would I secure a service method on a page?
E.G. I have a page "DocumentPage" with a method onDownload(id docID).
When the URL DocumentPage/onDownload/5 is called, the dispatcher is  
not even fired.
My Dispatcher is added like this
public void contributeMasterDispatcher(
                                        OrderedConfiguration<Dispatcher> 
configuration,
					@InjectService("AccessControlDispatcher") Dispatcher  
accessController)
        {
                configuration.add("AccessControlDispatcher", accessController,
                        "before:PageRender");
        }


Adding the same dispatcher with "before:OnEvent" is not helping either.
How can I secure service access on a page?

Thanks

Moritz