Programming Microsoft® Composite UI Application Block and Smart Client Software Factory

Chapter 7. Action Catalog Service

A. Problem Background

1. The benefits of loose coupling are not confined to the display of visible controls on user interfaces. A common problem in composite applications is that of coordinating loosely coupled parts of business logic. One work item wants to take a certain action but doesn't know if doing so would be OK with the work items in the composite application, especially since the initiator doesn't know and doesn't really want to know exactly which other items are currently loaded in the application. It wants to say something like, "Hey, I'm about to do [this thing]; if anyone objects, let him speak now or forever hold his peace."

   Consider the hospital application that we've been working with throughout this ...