While visiting ODTUG Kaleidoscope 2009 in Monterey and talking to fellow BPM, SOA and EDA adepts I got this idea about creating a best practices and lessons learned blog series. This first blog is dedicated to best practices in the BPM and SOA-space based on cases from a presentation by Lonneke Dikmans. Subsequent blogs will dive into best practices and lessons learned for a specific product, methodology or technology.
Case I: Introducing BPM. Mistake: Organizational impact underestimated. Explanation: Successful delivery of BPM project, business heavily involved. Never used because they realized after delivery that changes in both the organization and the software were needed. Best practice 1. BPM and SOA are about business, IT and humans. Observe how people work, don’t just ask them.
Case II: Notifications. Mistake: Dependencies between processes modeled directly in the processes itself. Explanation: Process flow sometimes is influenced by other processes. This was modeled into every process: this makes processes tightly coupled to each other and hard to change. It resulted in deadlocks. Best practice 2. Use events to notify running processes. Best practice 3. Monitor & avoid exceptions.
Case III: New technology. Mistake: Use BPEL as a general purpose language. Explanation: BPEL is a domain specific language; it was designed to orchestrate (web) services. Someone coming from a homogeneous -for example PL/SQL environment- in their back office, could decide to rewrite everything in BPEL, even the service implementations. The progress of such a project is very slow, and doing things that used to be easy becomes very hard. Best practice 4. BPEL is a Domain Specific Language (DSL); use BPEL for orchestration only. Best practice 5. Use an Enterprise Service Bus (ESB) to expose services to consumers including BPEL. Best practice 6. Use Java for service implementation. Best practice 7. Use PL/SQL for persistent data manipulation and data integrity rules. Best practice 8. Use rules when you need customization, inference or when business rules are volatile.
Case IV: Quality of Service. Success: involve administrators early. Explanation: Someone designed their first SOA project with quality of service in mind. In production all the non-functional demands were met. Best practice 9: Design architecture for Quality of Service from the start … but only what you really need! Not everyone needs clustering, fail-over, high-availability, and so on.
Case V: Domains. Success: combine a top down with a bottom up approach. Explanation: By defining 6 business domains and one supporting domain, the service taxonomy and event definitions were easier to keep track of. Also defining an owner for some of the services and design guidelines for services that cross domains become possible. Best practice 10. Use domains and layers to facilitate making a taxonomy of services and defining design guidelines.
Conclusion. Think big, start small. Meet in the middle requires aligning Business, IT and People. Architects can be intermediaries. Sharing knowledge and experience is necessary.
The next blog in this series will dive into Web Services best practices.