Numerous classes, complex inheritance and containment hierarchies, and diverse patterns of dynamic interaction all contribute to difficulties in understanding, reusing, debugging, and tuning large object-oriented systems. To help overcome these difficulties, we introduce novel views of the behavior of object-oriented systems and an architecture for creating and animating these views. We describe platform-independent techniques for instrumenting object-oriented programs, a language-independent protocol for monitoring their execution, and a structure for decoupling the execution of a subject program from its visualization. Case studies involving tuning and debugging of real systems are presented to demonstrate the benefits of visualization. We believe that visualization will prove to be a valuable tool for object-oriented software development.

This paper describes a way of organizing information aboutan object-oriented program's execution. The context is our system for visualizing that execution. The critical constraints are completeness, compactness, and efficient retrieval. We describe our design and how it meets these constraints. 1 Introduction Much is known about how to characterize programs statically. Contemporary programming languages embody countless lessons learned over nearly a half century of modern computing. It's clear that a language must balance expressiveness and simplicity, abstraction and specificity, flexibility and robustness. The proportions can vary according to need, but programming language design is necessarily a compromise between conflicting goals. We can think of a programming language as defining a vast space of legal programs relatively few of which are of any practical use. To define a space we must have orthogonal dimensions. In the case of structured programming languages we might devote on...