Below are the different ways of sharing data between portlets. Just google and you will get the sample code.
Share Render parameters.
Share Data on the portletSession. Add attributes to the APPLICATION_SCOPE.
Share data by using portlet events
Share data through the cooperative portlets
Joined: Nov 26, 2007
Using an APPLICATION_SCOPE we can just share data among portlets that are in the same war file. But when there are multiple portlets on a page i..e multiple war files, then how can every portlet know about the logged in user and display customized content. Does it mean that we should use IBM Puma API to do that?