The Architecture of Service-Orientation

Thomas Erl presented on the Architecture of Service-Orientation to start the breakout sessions and build on his opening comments. The key challenge is that of the endless IT progress cycle – the business continually needs more and different support from IT to deal with changes to business models while IT has new and changing capabilities that can inspire or empower the business. This creates a never-ending cycle. He identified seven goals of service-orientation computing:

1. Increased intrinsic interoperability
2. Increased federation
3. Increase business and technology domain alignment
   Something clearly improved when the business and IT can share an understanding of business logic thanks to the use of business rules to build decision services
4. Increased vendor diversification options
5. Increased ROI
6. Increased Organizational agility
   Again, something improved by decision services within SOA as decision services are inherently more transparent and agile services.
7. Decreased IT burden
   Empowering the business so they can maintain decision services for themselves also increases this effect.

He went on to discuss eight principles of Service-Orientation:

• Standardized service contract
• Service Loose Coupling
• Service Abstraction
• Service Reusability
• Service Autonomy
• Service Statelessness
• Service Discoverability
• Service Composability

Thomas made the point that these principles build on a long history of design approaches. They are evolutionary not revolutionary. The approaches results in four characteristics of SOA:

• Business-Driven
  The evolutionary path of the technology architecture is driven by the evolution of the business. Not only is this critical to SOA it is the key element of SOA that is enhanced and supported by the use of enterprise decision management to develop decision services.
• Vendor-Neutral
• Enterprise-Centric
  Interestingly he means the same as we do with the “E” word (Enterprise). It does not mean you have to do SOA, or decision management, enterprise-wide. It just means you have to be enterprise-centric and think of assets (services, decisions) as enterprise assets.
• Composition-Centric

Thomas believes that four types or scopes of SOA can be seen. A service architecture is the first scope. Building on this is a service composition architecture that can be extended to a service inventory architecture before you finally reach a service-oriented enterprise architecture.

All these elements tie back to the endless IT cycle with which he started.