In this example, there are two portlets deployed in a single portlet application: Portlet1 and Portlet2.
A page with four portlets: two instances each of Portlet1 and Portlet2.
The same page, with all portlets in edit mode. This lets you see the message mappings: the inputs and outputs of the portlets. It's set up so that the Portlet1's on the left talk to the Portlet2's immediately to their right.
Send a message from the top Portlet1. This will be put in public message box "b_val".
The message is received by the top Portlet2 (which is configured to read from "b_val").
Next, send a different message in the bottom Portlet1: this portlet is configured to send its message to the "2nd b_val" public message box.
The second message is retrieved by the bottom Portlet2 from "2nd b_val". The top Portlet2 still sees the first message as it is still reading from "b_val".
In Edit mode on the bottom Portlet2, change its mapping so that it reads its message in from "b_val" instead of "2nd b_val".
As soon as we return to View mode, the bottom Portlet2 now retrieves the message from public message box "b_val", originally sent by the top Portlet1.
