Event notification?

I've been learning a lot lately about adding event driven capabilities to custom objects, like the INotifyPropertyChange event which tells every consumer of a particular object that something changed and to update the display.

However, I want to take this one step further and apply this to a n-tier application. Basically, the middle tier will have a cache of objects. The client tier will consume these objects. Any change made to an object on in the cache on the middle tier will fire an event so all current consumers of that object will receive an event.

Would this use the TCP class? Any pointers on how to go about this would be appreciated.

I suspect the implementation will depend upon the IPC you intend to use to interface the n tiers together. In a networked application it might be natural to use something like Winsock (VB6) or the TCP class for .Net, which can handle asynchronous events. So, when your middle tier detects a change to an objectit can send a message to the other tiers and your code could the perform the necessary refresh.