Saturday, September 8, 2007 Architecture Best Practices

This is the second of a series of best practices I considered when starting a new workflow. Note that manye of these Best Practices are 2003 specific. They will be re-evaluated with the new BlackPearl release.

1) Understand When to Use provides the layer of human-to-human and human-to-system process definitions. typically compliments the middle layer business logic in a traditional three-tiered architecture. BizTalk workflow is used for system-to-system business workflow definition and specializes as a data broker. The native pattern of BizTalk is to serve as an Enterprise Bus for data between line of business applications. Integration Services (SSIS) for SQL Server 2005 can be used as the “poor man’s” BizTalk but should be limited in its usage as an ETL facility. can be the hub for human related workflows to start BizTalk or SSIS data workflows.

2) Decouple External Data Request with XML
Using XML to pass data between and external actors will ensure for a more configurable and manageable process over its lifetime.

3) Understand Integration with Line of Business Systems
Versioning should be accounted for whenever interacting with anything external to When integrating with external applications, the introduction of a version number should be considered especially when process instances may have a long life-cycle.

4) Design for Long Running Processes
When designing long running and large processes it is highly recommended that the process is broken up into several smaller processes. This allows for flexibility and manageability of the process definitions if things change while a process instance is in flight. Use the IPC server event and create a master child or a daisy chain of process that as a whole make up on large process. Note this is not recommending that processes are used as a sub function.

5) Design with Maintainability in Mind
A reality is that processes change with time due to evolving business rules. Locate all places where there is a possibility of change and consider what types of changes will be made and how they can be resolved. Understand the service level agreement of the process; for instance can a process instance be stopped and started over if there is a change request? If not, understand where a configuration can be introduced. A configuration is not just the usage of the string table or configuration file. A web service, database, sub-process, etc. could be introduced to allow for more flexibility in handling changes.

6) Handling Volatile Business Rules
Line Rules are no more than standard if statements in structured programming; if this do that. If Line Rules are going to be volatile and it is required they are up to date at all times it is recommended that those rules be externalized. Use web services, BizTalk Business Rule Engine, BlackPearl Business Rule Engine (TBD), Database, etc.

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