How portlet communicate with other application

Dongyu Yang <[email protected]> Thu, 30 Aug 2012 21:57:28 +0800
Newsgroups gmane.comp.jakarta.jetspeed.user
Message-ID <CA+84s3UitqVs=-v8qDvLTf7oSSZx4U+Pc_hdXzLGksHDtqsrkw@mail.gmail.com>
Hi all:
       I am newer of jetspeed2, and I want to konw how can a portlet
communicate with other application?

       Thanks for your help!