Introduction to OCL

Visual modeling languages are appealing because “a picture tells more than a thousand words”. The UML is such a visual language and is well known for its graphical notation and diagramming techniques. However, pictures often only tell half of the story and additional information needs to be captured in a different way. For this reason the UML includes the Object Constraint Language (OCL), a textual language which allows a UML modeler to specify these additional constraints. This tutorial shows the importance of constraints as an object-oriented modeling technique and how they add value to the visual modeling techniques and help “telling the complete story”. The OCL language itself and the connection with the visual UML diagrams is thoroughly explained. The final part of the tutorial will show how one can achieve a good balance between the visual and constraint modeling in UML. Biography: JOS WARMER is senior consultant in IBM’s European Object Technology Practice. He was co-author of the IBM/ObjecTime proposal for an object analysis and design language to the OMG and was the representative of IBM in the UML 1.1 core team. He is the chief architect of OCL. Jos has been active in the OT community since 1985, as a trainer, mentor and consultant. ANNEKE KLEPPE has over seven years of experience with object technology, and runs a training and coaching company, Klasse Objecten (“Class objects”): clients include PTT Telecom, NCR, IBM, and the Dutch government. For Dutch PTT Research, she has worked on conformance testing (TTCN), formal specification languages (LOTOS) and established a centre for object technology. She has extensive experience of UML, C++ and Smalltalk. ANNEKE and JOS are co-authors of “The Object Constraint Language: precise modeling with UML” [AWL] and two other books on OT.