Introduction
The first version of the portlet specification, JSR-168/portlet1.0, did not include any support for Inter Portlet Communication. The second version, JSR-286/ portlet2.0, which is supported for IPC Mechanism.
IPC is made easy with JSR-286 to share the data between two portlets. Using IPC mechanisms, we can share the data from ACTION to VIEW phase and VIEW-VIEW Phase.
There are 3 ways to share the data between 2 portlets.
1. Portlet session
2. IPC Mechanisms
2.1 Public Render Parameters
2.2 Event
2.3 Client-Side IPC
3. Cookies