Publications

This paper presents an approach for the automated generation of proof obligations for OO program refinement defined in the rCOS language. We first extend the mechanization of the refinement calculus done by von Wright in HOL, representing the state of a program as a graph instead of a tuple, in order to deal with object-orientation. The state graph structure is implemented in Isabelle, together with definitions and lemmas, to help the manipulation of states. We then show how proof obligations are automatically generated from the rCOS tool that can be loaded in Isabelle to be proved. We illustrate our approach by generating the proof obligations for a simple example, including object access and method invocation.

 We present the roadmap of the design and progress of a theory supported tool for component-based model driven software development (CB-MDD). First the motivation for using CB-MDD, its needs for a theoretical foundation and tool support are discussed, followed by an overview of the development of the theory and a prototype tool. The initial experiences with the tool are summarized, and based on the lessons learned, the further development trajectory leading to further integration with transformation and analysis plug-ins is delineated.

 Component-based development allows to build software from existing components and promises to improve software reuse and reduce costs. For critical applications, the user of a component must ensure that it fits the requirements of the application. To achieve this, testing is a well- suited means when the source code of the components is not available. Robustness testing is a testing methodology to detect vulnerabilities of a component under unexpected inputs or in a stressful environment. As components may fail differently in different states, we use a state machine based approach to robustness testing. Firstly, a set of paths is generated to cover transitions of the state machine, and it is used by the test cases to bring the component into a specific control state. Secondly, method calls with invalid inputs are fed to the component in different states to test the robustness. By traversing the paths, the test cases cover more states and transitions compared to stateless API testing. We apply our approach to several components, including open source software, and compare our results with existing approaches.

Component based development allows to build software upon existing components and promises to improve software reuse and reduce costs. To gain reliability of a component based system, verification technologies such as testing can be applied to check underlying components and their composition. Conformance testing checks the consistency between the behavior and component specifications. On the other hand, robustness testing detects vulnerability of software with unexpected input or stressful environment. Existing robustness testing tools aim to crash components with preset values of different data types. But they do not take into account component states, which are vital to the detecting robustness problem of a component. We propose a state machine based approach to detect robustness problems of components. Firstly, a set of paths is generated to cover transitions of the state machine. Test inputs which follow the paths achieve high coverage of the system states and examine more transitions than stateless API testing. Secondly, invalid inputs and inopportune method calls are fed to the component in different states to test the robustness. When unexpected exceptions arise in the test runs, robustness failures are reported. We do a case study on a component from an open source software and it results in positive results.

Component-based development allows one to build software from existing components and promises to improve software reuse and reduce costs. For critical applications, the user of a component must ensure that it fits the requirements of the application. To achieve this, testing is a well-suited means when the source code of the components is not available. Robustness testing is a testing methodology to detect the vulnerabilities of a component under unexpected inputs or in a stressful environment. As components may fail differently in different states, we use a state machine based approach to robustness testing. First, a set of paths is generated to cover transitions of the state machine, and it is used by the test cases to bring the component into a specific control state. Second, method calls with invalid inputs are fed to the component in different states to test the robustness. By traversing the paths, the test cases cover more states and transitions compared to stateless API testing. We apply our approach to several components, including open source software, and compare our results with existing approaches.

The refinement calculus provides a methodology for transforming an abstract specification into a concrete implementation, by following a succession of refinement rules. These rules have been mechanized in theorem-provers, thus providing a formal and rigorous way to prove that a given program refines another one. In a previous work, we have extended this mechanization for object-oriented programs, where the memory is represented as a graph, and we have integrated our approach within the rCOS tool, a model-driven software development tool providing a refinement language. Hence, for any refinement step, the tool automatically generates the corresponding proof obligations and the user can manually discharge them, using a provided library of refinement lemmas. In this work, we propose an approach to automate the search of possible refinement rules from a program to another, using the rewriting tool Maude. Each refinement rule in Maude is associated with the corresponding lemma in Isabelle, thus allowing the tool to automatically generate the Isabelle proof when a refinement rule can be automatically found. The user can add a new refinement rule by providing the corresponding Maude rule and Isabelle lemma.