Architecture Reconstruction

Intended vs. realized architecture. Evaluation of an architecture's properties is critical to successful system development. However, reasoning about a system's intended architecture must be recognized as distinct from reasoning about its realized architecture. As design and eventually implementation of an architecture proceed, faithfulness to the assumptions of the intended architecture is not always achieved. This is particularly true in cases where the intended architecture is not completely specified, documented or disseminated to all of the project members. This problem is exacerbated during maintenance and evolutionary development, as architectural drift and erosion occur.

Why architecture reconstruction important. To apply reasoning about the properties of a system's intended architecture to the properties of the implemented system, we must either ensure that the realized architecture conforms to the intended architecture or change the intended architecture to match reality. Both cases may require reconstructing the architecture of the realized system.

Phases of reconstruction. Architecture reconstruction is an iterative and interactive process, comprising four phases.

• The first phase is the extraction, from implementation artifacts (including source code and dynamic information such as event traces), of a set of extracted views that represent the system's fundamental structural and behavioral elements.
• The second phase is fusion of the extracted views to create fused views that augment or improve the extracted views.
• During the third phase, the analyst iteratively and interactively develops and applies patterns to the fused views to reconstruct architecture-level derived views. Patterns provide the medium for an analyst to express their understanding of a system's architecture as structural and attribute-based relationships among its components.
• Finally, the derived views may be explored for the purposes of evaluating architectural conformance, identifying targets for reengineering or reuse and analyzing the architecture's qualities.

The reconstruction process can be most effectively supported by the integration of existing tools and techniques. There currently exist a large number of commercial and research tools that provide the basic mechanisms for view extraction. Similarly, there are several tools and techniques available for performing view fusion and reconstruction. The synthesis of these tools and techniques provides a support environment for software architects and analysts reconstructing architectures.

To compliment our previous work in reconstruction we are currently surveying tools that are available for reconstruction to determine the current state of the practice for reconstructing architectural representations. We will study the information that these tools extract with emphasis on how they present the extracted views and how they aid in analysis of legacy systems.

The SEI will assist organizations with architecture reconstruction exercises.