A formal framework for developing adaptable service-based applications

Web services are open, interoperable, easy to integrate and reuse, and are extensively used in many application domains. Research and best practices have produced excellent support for developing large-scale web-based applications implementing complex business processes. Flexibility and interoperability of web services make them well suited also for highly-customizable reactive service-based applications, that is interactive applications which serve few users, and can be rapidly adapted to new requirements and environmental conditions. This is the case, for example of personal data managers tailored to the needs of few specific users who want to adapt them to different conditions and requests. Classic development approaches that require experts of web service technologies do not well support this class of applications which call for rapid individual customization and adaptation by non-expert users. In this paper, we present the formal framework of a model-based approach that provides expert users with the ability of rapidly building, adapting and reconfiguring reactive service-based applications according to new requirements and needs. Moreover this formal approach will presumably allow adaptations and reconfigurations by non-expert users as well. The underlying technique integrates two user-friendly, visual and executable formalisms: live sequence charts, to describe control flow, and graph transformation systems, to describe data flow and processing. Main results of the paper are the specification and semantics of the integration and early analysis techniques revealing inconsistencies.