Re: Event Dispatcher and Failed Posted Notifications

Michael Caplan wrote: >Bertrand et al, > > > >I have been paying close attention to the proposed / approved Event >Dispatcher, as it seems to provide a very elegant solution to the problem of >inter-module coupling. I have spent some time in the code and working >through the unit tests to figure out how Event Dispatcher works. I think I >have my head around most of it, but there is one issue I can't seem to >figure out and I am hoping you or anyone else can help me solve it. > > > >The scenario is this: I am coding in an environment which has several >defined modules. Each module provides unique functionality (eg: article >module, calendar module, tracker module, etc....). Under certain scenarios, >these modules will need to interface with each other (eg: an article is >posted into the article module which requires the tracker module to be >updated so that it can track access to the article - or something like >that). So, module A posts an event (which is to be handled immediately) >which the dispatcher then forwards to an observer in module B. All good. >But let's say the event posted to module B fails. For whatever reason, >module A has a strong dependency on module B doing it's work, and upon >failure of module B's handled event it would be most desirable that module A >rolls back. Is there a way that the event poster can become aware of an >event failure (presuming it is an immediately posted event)? I think this might be better handled by exceptions if PHP5 is an option for you. You can also have object A (the poster) be the contained notification object (this is the usual way to go anyway) and have B (the receiver) use the contained object like suck: // In B, this is your callback function receiverMethod(&$notification) { // Do some work... if ($failed) { $A =& $notification->getNotificationObject(); $A->rollback(); $notification->cancelNotification(); } } Good luck, Bertrand Mansion Mamasam