@ArquillianResource is a way to inject extension/core controlled objects so they can be used by the user.

@ArquillianResource
URL url; <-- targeted containers http context

@ArquillianResource(SomeServlet.class)
URL url; <-- targeted containers http context where servlet is located

@ArquillianResource
InitialContext|Context context; <-- targeted containers initial context

@ArquillianResource
Deployer deployer; <-- the manual deployer