crm-4-0-plugins

(Lisle to Union is going to be a recurring series.  I'm going to attemptto write daily my thoughts on what I'm currently working on.  As to the name "Lisle to Union"?  That's the train I take to get into work every morning. :))

In my current project we are consuming data out of MS CRM.  Accounts and contacts to be precise. Pulling data out to display it is relatively easy using their web service apis and we are quite happy with the result.  Having one silo-ed system that is in charge of a very specific domain and requesting data from that domain from very well defined end points jives with my line of thinking.

But, there is one problem with not having control over the domain.  The problem is how do you find out about changes to data that you are interested in?  Account name changes, contact name changes, merging of entities, etc?  Luckily MS CRM has a rich plug-in model that allows you to receive messages when "interesting" things happen in the MS CRM pipeline.  I say "interesting" things because you can hook into every event that you need.

When I first started looking into the MS CRM Plug-in model I first thought "This so extensible that it is useless". The amount of configuration and registration that is required is quite frightening.  The awesome part is that the CRM 4 sdk has tools in it to make it super easy.  They have a plugin registration tool that makes it a snap to register a plug-in for the events you are interested in and a developer tool that makes it easy to re-register any changes to your plug-in during development. 

When you get a message from MS CRM you are passed a Context object that contains the entity that changed (which was the entity you said you wanted in the plug-in registration) and (here is the interesting part) the actual message that MS CRM processed.  You don't get a "here is the before and after" message (which is what I was expecting).  Since all of the APIs MS CRM uses are all passed on the Command Pattern, the easiest thing for them to do is pass you the command that it used.  In all honesty I find this pretty slick. (and I'm happy that we are using the Command Pattern in my current app (not through-out but in places where we didn't want to play the game of "What has changed on my data model?".  That is not a fun game to play.)

Unfortunately, for my first plug-in it seems I have tried to tackle one of the hardest problems in MS CRM.  Entity Merging.  There aren't a lot of examples out there for MS CRM and I can't find a single one for entity merging.  As soon as I get it figured out I'll post more in depth on it.