Is it a good idea to add a BRE policy to a specific application? ...
- the policies I've been given are specific to the application, so it seems appropriate
- but is it?
I've seen the actual "how to" on MSDN, but I'm interested in the "should you"
Yes, if using the BRE provides a benefit to the app, use it, just like many other components in the stack.
The question is usually what constitutes a 'benefit'. When used appropriately, the BRE can benefit developers and users by abstracting the 'rules' from the rest of the code and providing external means to maintain runtime behavior of the business process. However, implementing BRE as a config store when there are other config stores already in use is not a benefit to the Admin (one more thing they have to deal with). There are always trade-offs.
A similar question comes up quite often with the ESB Toolkit and my recommendation is always take the time to understand what it does, what problems it addresses and if it fits, use it.