Identifying Core Objects for Trace Summarization Using Reference Relations and Access Analysis

Abstract

Behaviors of an object-oriented system can be visualized as reverse-engineered sequence diagrams from execution traces. This approach is a valuable tool for program comprehension tasks. However, owing to the massiveness of information contained in an execution trace, a reverse-engineered sequence diagram is often afflicted by a scalability issue. To address this issue, we present in this paper a method for identifying core objects for trace summarization by reference relations and access analysis. We detect and eliminate temporary objects that are trivial for a system, and then estimate the importance of non-trivial objects. By grouping objects with a focus on highly important ones (i.e., core objects), we visualize the system's behavior in terms of intergroup interactions. Consequently, we obtain a readable size of a reverse-engineered sequence diagram containing the system's key behavior. We implemented our technique in our tool and evaluated it by using traces from open-source software systems. The results showed that our reverse-engineered sequence diagrams contained only less than 30 lifelines, whereas the original diagrams (no abstraction methods were applied) contained approximately 1,000 to 3,000 lifelines. Our proposed method achieved significant reduction of the horizontal size of the diagram and is expected to be a valuable tool for program comprehension.