Contract-Oriented Software Development for Internet Services

The fast evolution of the Internet has popularized service-oriented architectures with their promise of dynamic IT-supported inter-business collaborations. Realizing this promise involves integrating services which are geographically distant and are offered by a variety of organizations which do not fully trust each other. Indeed, collaboration presumes a minimum level of mutual trust. Wherever trust is perceived as insufficient, businesspeople turn to contracts as a mechanism to reduce risks. The ability to negotiate contracts (e.g. for quality of service, security, and distribution of information) and to provide services based on them is therefore one of the most pressing needs to make collaborations a reality. High-level models of contracts are slowly making their way into service-oriented architectures, but application developers are still left to their own devices when it comes to writing code that will comply with a contract concluded just before service provision. At the programming language level, contracts appear as separate concerns that crosscut through application logic. The aim of this project is to develop language-based solutions to the above problem through the formalization of contracts as behavioral interfaces and the design of appropriate abstraction mechanisms that would guide the developer in the production of contract-aware applications. In the project, we will concentrate on contracts dealing with performance (real-time) and information flow (confidentiality). The proposed programming language mechanisms will be formally described so that they are either correct by construction or their properties become amenable to formal proof.