"What I do not buy into is the idea that all systems should be seen either as services that expose their functionality only via unidirectional XML messaging or as clients of such systems"
We want as few a services running as possible for two reasons. Firstly, you don't want to waste the cpu on services that are never used. Second, the fewer services running, the fewers vunerabilities the system will have. To get a list of services curre
Substitute a standard web services interface for a speaking tube, a business rules management system for his encyclopedic knowledge of policies and regulations, data mining or predictive analytics for his customer knowledge and adaptive control for his experimentation and you have Decision Management. The Answerer but on an industrial scale.
JT has posted his view on rules and decisions and how they relate. Given that James talks more about services than events, I thought it would be worth reviewing his post from both a Complex Event Processing and a TIBCO BusinessEvents event processing platform perspective.
”Decision Services:
Support business processes by making the business decisions that allow a process to continue.
Support event processing systems by adding business decisions to event correlation decisions (they are often called Decision Agents in this context).
Allow crucial and high-maintenance parts of legacy enterprise applications to be externalized for reuse and agility.
Can be plugged into a variety of systems using Enterprise Service Bus approaches.”
Let’s start by recapping decisions services. Decision services are services, generally stateless ones, that answer business questions for other services. Decision Services typically have no side effects so they can be called whenever they are needed without the caller worrying that something will change in the system. This means that database updates, event generation or other actions taken as a result of the decision are taken by the caller not by the Decision Service. This is not 100% true but works as a general rule. To work, Decision Services need to contain all the logic and algorithms necessary to make the decision correctly.
As IBM absorbs ILOG it will be important that it continue to invest is this multi-platform approach. Not only are there some nice features in the .Net product (that I for one would like to see available to the Java product) but decision management with business rules is, for most companies, a multi-platform problem. The value of using business rules to decision management comes in part from making sure the same rules are used everywhere they are supposed to be used. While deploying business rules in Decision Services on SOA makes this easier, the best solution is to allow the rules to be packaged up and deployed as Java components, Web Services, .Net assemblies or COBOL code so that they can run natively on all the platforms that run the business.
Y. Ahn, S. Han, H. Kwak, S. Moon, und H. Jeong. WWW '07: Proceedings of the 16th international conference on World Wide Web, Seite 835--844. New York, NY, USA, ACM, (2007)