[xwiki-devs] [PROPOSAL] Introduce begin/end events standard

Hi devs, I would like to introduced a standardized (at observation API level) way to indicate that en event represent the beginning or the end of something. The idea is them to use it in things like activity stream to group events/whatever or in my case maintain a stack of states in the Execution context about the current action updated by listening to events. My immediate use case is to filter some modification in automatic watch feature (imported xar, crated wikis, etc.) but I feel that we need that information for a larger audience. In details my proposal is to introduce BeginEvent and EndEvent interface (feel free to suggest better names if you have some in mind). Then pushing the BeginEvent instance in the context in a stack of current events poped when receiving a EndEvent. Note that I don't not plan to put an id in Begin/EndEvent since it should not be needed if they are properly generated (some job can't finish if all it's sub jobs are not finished). WDYT ? -- Thomas Mortagne