Automated size analysis for OCL

  • Authors:

  • Fang Yu;Tevfik Bultan;Erik Peterson

  • Affiliations:

  • University of California: Santa Barbara, Santa Barbara, CA;University of California: Santa Barbara, Santa Barbara, CA;University of California: Santa Barbara, Santa Barbara, CA

  • Venue:
  • Proceedings of the the 6th joint meeting of the European software engineering conference and the ACM SIGSOFT symposium on The foundations of software engineering
  • Year:
  • 2007

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Abstract

An essential tool in object oriented modeling is the specification of cardinalities of associations between classes. In Object Constraint Language (OCL) such constraints are expressed as conditions on the sizes of the collections that correspond to associations. In this paper we present tools and techniques for automated verification of size properties of collection types in OCL. We automatically verify invariants related to the sizes of the collections of a class with respect to the pre and post-conditions of the methods of that class. Our approach is based on a size abstraction that abstracts away the contents of the collections, but preserves the constraints on their sizes. We implemented a tool which automates this abstraction by converting OCL expressions on collections to arithmetic expressions on their sizes. Following this translation, we employ an infinite state model checker, called Action Language Verifier (ALV), for size analysis. Size abstraction reduces the state space of the system and, hence, the cost of automated verification, and by focusing on size properties, enables us to use efficient, domain specific model checking techniques for automated verification. To demonstrate the effectiveness of our approach we conducted a case study on the OCL specification of the Java Card API. The OCL specification of the Java Card API consists of 31 classes and 150 methods. Using our tool, we translated the OCL specification of each class to Action Language and verified the size properties using ALV. Verification with ALV took only a few seconds per class and we revealed errors in 26 out of the 150 method specifications.