- Start with the premise that Processes DO CHANGE. Actually, the process tends to be the SAME. It is the policy within that PROCESS that CHANGES.
- Tracking is fundamental to the orchestration and rules.
- The Rules engine is a lightweight .NET application component that can run as an In-process within a BizTalk host.
- Developer will be able to drop a rules engine component into the BizTalk Orchestration designer.
What are rules?
- Basically they are predicates. (i.e. if
- Modify business policies (NOT processes) in real-time without rebuilding/redeploying.
- Rules engine can also be hosted in a WinForms component, or wherever!
- Security roles, define who can change these rules.
- Version management is also important; once rules are saved they are saved in SQL server. When they are published the ruleset they become immutable (i.e. they cannot be changed.)
- Rules engines can use English based vocabularies that map to .NET classes, database tables, XML Schemas.
- Instantiates the Policy Class... queries the Rules Store... holds rules in the rules cache.
- The Rules engine uses multiple Rules stores (XML / SQL Server / OleDB)
- Forward chaining inference mechanism.... [Finds all true statement.]
- Efficient pattern matching.
- Performance and scalability optimised.
- Eager-match algorithm for smaller rules sets & Microsoft patented algorithm for large rule sets.
The following design patterns describe when to call the Rules Engine: -
- To dynamically determine which orchestration to call.
- To determine the path within the orchestration. [Using inference]
- To execute logic instead of burying it in the code.
When to use what?
When should you code in the rule policy and when should you code in the orchestration?
- When there are a large number of permutations to encode in control.
- Fact-based inference where control cannot be predefined.
- Point-in-time evaluations
- Workflows that require formal Control structures, long running semantics, and messaging.
- When Control flow is well understood and performance is critical.
- Visibility and tracking are important. (Process rather than policy)