Prior to JSR 286, the support for inter portlet communication was rather minimal and information sharing between different portlets was accompalished primarily using application scoped session objects or vendor specific APIs. Both of above methods were rather problematic as in the former maintaining the uniqueness of the session attribute over a complex aaplication was a concern and in the later portability of the portlet was hampered. In order to provide coordination between portlets the Java Portlet Specification v2.0 (JSR 286) introduces the following mechanisms:
An example where a portlet may want to offer receiving events is for state changes triggered by simple user interactions, e.g. adding an item to a shopping cart. By offering this as an event to other portlets these can trigger adding items to the shopping cart based on the user interactions happing inside these portlets.
More details here:
http://blog.xebia.com/2009/04/19/inter-portlet-coordination-with-jsr-286/
- public render parameters in order to share render state between portlets.
- portlet events that a portlet can receive and send.
An example where a portlet may want to offer receiving events is for state changes triggered by simple user interactions, e.g. adding an item to a shopping cart. By offering this as an event to other portlets these can trigger adding items to the shopping cart based on the user interactions happing inside these portlets.
More details here:
http://blog.xebia.com/2009/04/19/inter-portlet-coordination-with-jsr-286/
