While working on some Windows Workflow projects I was having some trouble getting ExternalDataExchangeServices to raise events. In searching for an answer, I came across this wiki that has the beginnings of some good material. I think the Windows Workflow community might want to contribute to efforts like this because, frankly, WF can be hard.

Incidentally, the reason my events weren’t getting raised was found right on the wiki: I was raising an event from a service where the event arguments were serializable but the sender was not. Everything has to be marked [Serializable], even the sender. Sounds obvious now, but let me tell you what a pain that was to try and track down.