i am using the the IPC-technics of the HelloWorldIPC sample in my own Portlet application (two portlets on one portal site). It works very well. There are PortletA and PortletB. PortletB implements the listener so that PortletA can modify the behaviour of Portlet B. My question is now, can i add a second Listener to PortletA, so that PortletB can also modify the behaviour of PortletA ? My application is packed like the HelloWorldIPC sample in one sar file.