Understanding Software Architectures: Tracing architectural knowledge in software architecture documentation

Introduction " The reality is more excellent than the report. " – Ralph Waldo Emerson This thesis is about understanding software architecture documentation and how the integration of software architecture description and rationale can improve this understanding. Understanding software architecture (documentation) is important in the complete life cycle of a software architecture; during development, maintenance and evolution. Understanding the documentation of a software architecture is difficult. A description of the design of a software architecture is far from enough to make it understandable. A description does not answer why a design is done as it is, or how the software architecture arrived at the present design. To understand a software architecture, one must know and understand the reasoning behind the design, i.e. the rationale, and how architectural artifacts are related. Research in software architecture can be seen in two perspectives: a traditional and modern one. The traditional perspective describes the design of a software architecture in terms of components and connectors and how these are arranged. The second, more recent one describes software architecture in terms of the decisions and rationale that led up to the software architecture. Research and practice so far have been confined within these perspectives, but an integration of the traditional and modern perspectives to describe software architecture promises to solve some of the problems of software architecture. Figure 1 illustrates these two perspectives. Both perspectives are about representing architectural knowledge, which is done in either a non-formalized or a formalized approach. The research areas that result from this subdivision are traditional software architecture documentation, modeling of software architectures, templates for capturing architectural decisions, and ontologies for representing architectural knowledge. This thesis will analyze the problems of understandability in these areas except modeling of software architectures, because this area is not relevant for documentation of software architecture. The focus lies on how understandability of software architecture documentation can be improved by integrating it with rationale. The remainder of this chapter gives a short introduction to the traditional and modern perspectives on software architecture description and rationale. This is followed by a section on how an integration of these perspectives promises to solve some