The purpose of events is to simplify business logic customization while not impeding upgradeability and general extensibility. However, there is one particular class of events that may cause troubles: OnAfter* table events. There are four of them: OnAfterInsert, OnAfterModify, OnAfterDelete, and OnAfterRename.
If you need them, you must be careful.
When I was writing my last post I had a distinct feeling that I was trampling over some boundaries of good NAV design. After all, you should not do stuff like that, NAV isn’t meant to do things like that, or at least that was how I felt.
And then two things happened.
First, I asked myself: what the heck, why not? What exactly is NAV meant to do, and why not things like that? If folks at Vedbæk didn’t provide an out-of-the-box solution for the problem, why should the problem stay unsolved?
Second, my dear friend and a fellow MVP, Hrvoje of Hudo’s Vibe, identified the thing as the mediator pattern. So, the thing I’ve done to NAV, civilized world has been doing to their programming environments for a long time.
And then I decided to take it all to a different level altogether, and expand the simple class which didn’t do much but raise events on itself when its method was called, into a full-scale framework. And here it is, the mediator pattern incarnated into a brand new Dispatcher class, adapted to NAV, and with features that make it truly flexible. I do not dare starting to think what are all the situations where you could put this thing to use in NAV.
Read on.
Four months ago I attended a conference, where I had a chance to listen to Miha Kralj, an architect at Microsoft, talk about architectures. It was one of the best presentations I ever attended, and ever since I had this topic in queue, but never really had chance to write about it. Most of the stuff he talked about reminded me of some bad experiences about architectures on projects I’ve worked on. Most of stuff here is also not my original contribution to the universal pool of knowledge, and I reuse it with the permission of the author, so Miha, thanks! What I did, however, is that I applied general principles to specific Microsoft Dynamics NAV situations.