Open-world Sofware: Specification, Verification, and beyond Dissertation Committee

Open-world software represents a new class of software, which exhibits new features that often demand for rethinking and extending the traditional methodologies and the accompanying methods and techniques. Open-world systems are built by composing heterogeneous, third-party components, whose behavior and interactions cannot be fully controlled or predicted; moreover, the environment they interact with is characterized by frequent, unexpected, and welcome changes. In this thesis we deal with a particular class of open-world software, represented by service-based applications (SBAs). We focus on three specific aspects related to the development and provisioning of SBAs: specification, verification, and reputation management. With respect to these aspects, we provide methods and techniques that are i) suitable to deal with aspects such as change, evolution, and reliance on thirdparties, and ii) able to improve the overall quality of the systems they are applied to. More specifically, concerning specification, we report on the findings of a study that analyzed requirements specifications of SBAs developed in research settings and in industrial settings. These findings have then driven the design of SOLOIST, a language used to specify the interactions of SBAs. Regarding verification, our contribution is twofold; we propose: i) a technique for automatically generating the behavioral interfaces of the partner services of a service composition, by decomposing the requirements specification of the composite service; ii) a framework for the definition of verification procedures (encoded as synthesis of semantic attributes associated with a grammar) that are made incremental using an approach based on incremental parsing and attributes evaluation techniques; Finally, as for reputation management, we present a reputation-aware service execution infrastructure, which manages the reputation of services used by composite SBAs in an automated and transparent manner.