Abstract. A software design is often modelled as a collection of UML diagrams. There is an inherent need to preserve consistency between these diagrams. Moreover, through evolution those diagrams get modified leading to possible inconsistency between different versions of the diagrams. State-of-the-art UML CASE tools provide poor support for consistency maintenance. To solve this problem, an extension of the UML metamodel enabling support for consistency maintenance and a classification of inconsistency problems is proposed. To achieve the detection and resolution of consistency conflicts, the use of description logic (DL) is presented. DL has the important property of being a decidable fragment of first-order predicate logic. By means of a number of concrete experiments in Loom, we show the feasibility of using this formalism for the purpose of maintaining consistency between (evolving) UML models.

Abstract-For a system of distributed processes, correctness can be ensured by (statically) checking whether their composition satisfies properties of interest. However, Web services are distributed processes that dynamically discover properties of other Web services. Since the overall system may not be available statically and since each business process is supposed to be relatively simple, we propose to use runtime monitoring of conversations between partners as a means of checking behavioral correctness of the entire Web service system. Specifically, we identify a subset of UML 2.0 Sequence Diagrams as a property specification language and show that it is sufficiently expressive for capturing safety and liveness properties. By transforming these diagrams to automata, we enable conformance checking of finite execution traces against the specification. We show how our language can be used to specify the Specification Property System (SPS) [1]. We describe an implementation of our approach as part of an industrial system. Finally, we discuss our experience of specifying and monitoring a number of properties from three existing applications.

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Abstract. For a system of distributed processes, correctness can be ensured by (statically) checking whether their composition satisfies properties of interest. However, web services are distributed processes that dynamically discover properties of other web services. Since the overall system may not be available statically and since each business process is supposed to be relatively simple, we propose to use (on-line) runtime monitoring of conversations between partners as a means of checking behavioural correctness of the entire web service system. Our framework allows application developers to specify behavioural correctness properties. By transforming these properties to finite-state automata, we enable conformance checking of finite execution traces of web services described in BPEL against the specification. Moreover, when violations are discovered at runtime, we automatically propose and rank recovery plans which users of the system can then select for execution. For some of the violations, such plans essentially involve "going back" -compensating the occurred actions until an alternative behaviour of the application is possible. For other violations, such plans include both "going back" and "re-planning" -guiding the application towards a desired behaviour. We report on the implementation and experience with our monitoring and recovery system, and discuss the implications that the move to "smart internet" [39] may have on our approach.

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As the standard for object-oriented analysis and design, the UML (Unified Modeling Language) metamodel, as well as contemporary CASE (Computer-Aided Software Engineering) tools, must provide adequate and integrated support for all essential aspects of software evolution. This includes version control, traceability, impact analysis, change propagation, inconsistency management, and model refactorings. This chapter focuses on the latter two aspects, and shows how tool support for these aspects can be provided. First, we extend the UML metamodel with support for versioning. Second, we make a classification of the possible inconsistencies of UML design models. Finally, we use the formalism of description logics, a decidable fragment of first-order predicate logic, to express logic rules that can detect and resolve these inconsistencies. We also show how the logic rules are used to propose model refactorings. As a proof of concept, we report on the results of initial experiments with a prototype tool we developed for this approach.

When model-checking reports that a property holds on a model, vacuity detection increases user confidence in this result by checking that the property is satisfied in the intended way. While vacuity detection is effective, it is a relatively expensive technique requiring many additional modelchecking runs. We address the problem of efficient vacuity detection for Bounded Model Checking (BMC) of LTL properties, presenting three partial vacuity detection methods based on the efficient analysis of the resolution proof produced by a successful BMC run. In particular, we define a characteristic of resolution proofs-peripherality-and prove that if a variable is a source of vacuity, then there exists a resolution proof in which this variable is peripheral. Our vacuity detection tool, VaqTree, uses these methods to detect vacuous variables, decreasing the total number of model-checking runs required to detect all sources of vacuity.