Service Oriented Architecture: Why OOAD and BPM are Not Enough

An interdisciplinary modeling approach for SOA projects
Olaf Zimmermann (ozimmer@de.ibm.com), Senior IT Architect, IBM
Pal Krogdahl (pal.krogdahl@se.ibm.com), Solution Architect, IBM
Clive Gee (clive@us.ibm.com), Senior Solution Architect, IBM

2 Jun 2004

Experience from first Service-Oriented Architecture (SOA) implementation projects suggest that existing development processes and notations such as Object-Oriented Analysis and Design (OOAD), Enterprise Architecture (EA) frameworks, and Business Process Modeling (BPM) only cover part of what is required to support the architectural patterns currently emerging under the SOA umbrella. Thus, there is a need for an enhanced, interdisciplinary service modeling approach.

In a recent interview at Info World (see Resources), Grady Booch stated that "the fundamentals of engineering like good abstractions, good separation of concerns never go out of style", but he also pointed out that "there are real opportunities to raise the level of abstraction again." Past experience indicates that the abstraction level has to be raised up to the business domains a company deals with, taking the entire enterprise IT landscape into account.

SOA, for example, as introduced by Mark Colan in the article, "Service-Oriented Architecture expands the vision of Web services, Part 1", is an emerging architectural style for crafting next-generation enterprise applications. While the SOA approach strongly reinforces well-established, general software architecture principles such as information hiding, modularization, and separation of concerns, it also adds additional themes such as service choreography, service repositories, and the service bus middleware pattern.

A structured approach or analysis and design method is required to craft SOAs of quality. As none of the existing approaches met the authors requirements on recent SOA projects, they suggest combining elements from well-established practices such as OOAD, EA, and BPM, complementing them with innovative elements upon demand.