In his posting SOA=Orchestration, David Linthicum said, among other things,
"Orchestration is a godlike control mechanism that's able to put our SOA to work, as well as provide a point of control. Orchestration layers allow you to change the way your business functions, as needed, to define or redefine any business process on-the-fly. This provides the business with the flexibility and agility needed to compete today."
"Orchestration must provide dynamic, flexible, and adaptable mechanisms to meet the changing needs of the domain. This is accomplished through the separation of process logic and the back-end services employed."
As you read this you can immediately see the value of business rules. Business rules management systems:
- Offer a single point of control for managing business rules, something your orchestration layer needs
- Support change on the fly by the people who understand the business, the people who know how your business functions should evolve
- Deliver real business agility by reducing the time it takes to change the way you do business
- Separates logic from back-end technology or plumbing
So I would argue that an orchestration layer should include a business rules management solution as a key delivery technology (assuming you pick one that can be deployed into an SOA).
In addition, it should be noted that the name of the SOA game is to create modular software applications that can work together and allow each component of the system to focus on what it does best. This allows organizations to pick the right technology for each kind of service. By picking a business rules management technology to build these kinds of services one can also avoid the issue of how to effectively manage the consistency of business decisions delivered. Business rules management systems provide a highly effective and efficient mechanism for managing decision logic. The key to BRMS is the use of a centralized rules repository, within which resides the decision logic that applications use in their process interactions. This allows for a single point of change and control across services and across the orchestration layer.
Business rules management systems fit within a service-oriented architecture, and a BRMS can act both as an orchestration layer and as a way to deliver sophisticated decisioning services.