Service Oriented Design

Service oriented analysis and design is to bridge business architecture and IT architecture. Start from business requirements, define services (functions for one service, the right size), model a services (interface for one service, interaction between services), then use automatic tools to generate classes and code for service implementation. Some Q&A:

1. How to find the right services?
Features of a service: Service is a concept in business, rather than in IT terminology. A service should be bound to an explicit business goal or function. A service should have user inputs (ref. my paper Between Service Science and Service Oriented Software System) …
A service is a relatively independent function of the target system. It should be normally bigger than classes in a normal OO design.

2. Services vs. classes
A service is implemented by multiple (even numerous) classes. After the interface of a service is designed (e.g. in WSDL), the generation of implementation can be automatic. To the current automatic translation tool, the size of the service should not be too big. Otherwise, the code is not coherent.

3. Tools to help design a service
UML Use cases
UML logic architecture
UML activity diagram (with port definition?)
UML domain diagram
Not UML class diagram