Experimenting with Real-Time Specification Methods:

The Model Multiplicity Problem

Mor Peleg and Dov Dori

Area of Information systems Engineering

Faculty of Industrial Engineering and Management

Technion, Israel Institute of Technology, Haifa 32000, Israel

{mor, dori}@ie.technion.ac.il; Fax 972-4-8235194 , Tel: 972-4-8294409 / 2921


The Object-Process Methodology (OPM) specifies both graphically and textually the system’s static-structural and behavioral-procedural aspects through a single unifying model. This model singularity is contrasted with the multi-model approach taken by existing object-oriented system analysis methods. These methods employ several models for specifying various system aspects – mainly structure, function, and behavior. Object Modeling Technique (OMT), the main ancestor of Unified Modeling Language (UML), extended with Timed Statecharts, represents a family of such multi-model object-oriented methods. Two major open questions have been whether or not a single model, rather than a combination of several models, enables better system specification, and which of the two alternative approaches yields a specification that is easier to comprehend. In this study, we address these questions through a controlled experiment, and establish empirically that a single model methodology – OPM – is more effective than a multi-model one (OMT) in generating better system specification. The paper also discusses the significant differences between OPM and OMT that were found in specification comprehension.