Sections from my thesis (work in progress!) of possible relevance to JSR-286. Hope they are of use :)

They describe limitations of JSR-168 encountered while developing portlets generally, and then when developing the IPC library. (Final summary at the end)

The IPC sections mostly concentrate on the design of the library, which will not be of direct use as it was constrained to fit within JSR-168, whereas the IPC in JSR-286 will of course be much freer to do what it likes! However, our specific messaging requirements and use cases may be of interest.

Although the thesis chapters on this site are the most detailed and up-to-date, this work was also presented at All Hands 2005 - paper (PDF 0.5MB), presentation (PPT 8MB).