Abstract Single Stepping in Event�Visualization Tools

Event visualization tools are commonly used to facilitate the debugging of distributed applica� tions. Although these tools provide a graph� ical view of distributed executions � they are frequently insu�cient for full debugging pur� poses. The need for traditional debugging op� erations is often overlooked when building these tools. One of the most useful operations in traditional debuggers is single stepping. How� ever � the di�culties faced when dealing with partially ordered�executions have deterred the development of a single�stepping method for concurrent processes. This paper describes a single�stepping operations suitable for event� visualization tools. Three di�erent methods for single stepping are presented � global�step� step�over and step�in. Abstraction techniques are commonly used to reduce the overwhelm� ing amount of detail presented to the user. Ac� cordingly � single stepping in the presence of ab� straction is considered. The operations de�ned in this paper have been implemented in Poet� aPartial Order Event Tracer � and examples of the resulting visualizations are given.