Recurring Architectural Decisions - A Context-Specific Guide through SOA Design

Software architects view systems under construction from multiple viewpoints such as the 4+1 logical, development, physical, process, and scenario viewpoints. Their methods and tools typically center on these structural viewpoints. The capturing of architectural decision rationale, however, is another essential viewpoint, which only recently has become a software architecture research topic. Unfortunately, most of the emerging architectural decision modeling tools only support the retrospective capturing of decisions made; they do not support a proactive modeling of decisions required (issues) and available solutions (alternatives). This limits the opportunities for reuse.

In this lecture, we first present two large-scale industry projects to motivate the benefits of proactive architectural decision modeling. Next, we introduce a meta model which separates decisions required from decisions made to support reuse. As meta model instances, we present excerpts from a 500-node Service-Oriented Architecture (SOA) decision model harvested from full lifecycle projects since 2001: We investigate selected SOA design decisions such as the selection of integration style and message exchange patterns, transaction management, and service granularity. We also demonstrate how to capture decisions required and their alternatives in Architectural Decision Knowledge Wiki, a Web 2.0 collaboration system and application wiki supporting decision maker collaboration over the Web. Meta model, reusable SOA decision model and application wiki jointly support real-world usage scenarios such as project team education, architecture design method support, facilitation of technical quality assurance reviews, and IT governance.

Dr. Olaf Zimmermann is a Research Staff Member in the IBM Zurich Research Lab. Olaf recently received his Ph. D. (Dr. rer. nat) from Suttgart  University, Germany (Prof. Frank Leymann); in his Ph. D. dissertation, he  created an architectural decision modeling framework for Service-Oriented  Architetcure (SOA) design. Olaf also is an Open Group Master Certified and  IBM senior certified Executive IT Architect; he has 20 years of IT industry experience.

Previously, Olaf was a solution architect, helping IBM clients designing enterprise-scale SOA/Web services and Java Enterprise Edition (JEE)  solutions on numerous professional services projects. He also educated  practitioners around the world on emerging middleware technologies. In the  beginning of his career, Olaf worked as a scientific consultant in the IBM  European Networking Center (ENC) in Heidelberg, Germany, focusing on  industry-specific middleware frameworks for systems and network management.

Olaf is a regular conference speaker and an author of the Springer text book „Perspectives on Web Services“. He contributed to several IBM Redbooks  such as „Web Services Wizardry with WebSphere Studio Application  Developer“.