Engineering Service Oriented Applications: From StPowla Processes to SRML Models

Abstract

Abstract. Service Oriented Computing is a paradigm for developing software systems as the composition of a number of services. Services are loosely coupled entities, can be dynamically published, discovered and invoked over a network. The engineering of such systems presents novel challenges, mostly due to the dynamicity and distributed nature of service-based applications. In this paper, we focus on the modelling of service orchestrations. We discuss the relationship between two languages developed under the SENSORIA project: SRML as a high level modelling language for Service Oriented Architectures, and STPOWLA as a process-oriented orchestration approach that separates core business processes from system variability at the end-user's level, where the focus is towards achieving business goals. We also extend the current status of STPOWLA to include workflow reconfigurations. A fundamental challenge of software engineering is to correctly align business goals with IT strategy, and as such we present an encoding of STPOWLA to SRML. This provides a formal framework for STPOWLA and also a separated view of policies representing system variability that is not present in SRML.

Model-Driven Development of Adaptable Service-Oriented Business Processes

“…The latters are discussed in [7]; here we concentrate on the formers, and call them simply policies. For instance, the generic BankEvaluation process can be adapted to specific situations via policies, like:…”

From StPowla processes to SRML models

“…We model a workflow using a graphical notation presented in [GRM06c]. However, for the purpose of this paper we also adapt the more concise textual grammar presented in [BGR08] which shows how complex processes can be composed:…”

“…they last for the duration of the workflow instance and usually will be made during the execution of the instance, rather than applied to the overall workflow model. STPOWLA allows for both functional and non-functional changes to a workflow, the former have been introduced in [BGR08]. The non-functional changes are called refinement and provide a means to select the most appropriate service based on the current environment when a service is invoked.…”

“…This paper extends on [BGR08] by introducing a mapping for the refinement aspects of STPOWLA and providing more detail on the reconfiguration mapping to enhance clarity. Furthermore we consider an example for the use of SRML and STPOWLA in combination based on an industrial case study from the SENSORIA project [sen].…”

“…In this paper, we give an overview of the STPOWLA approach, including the extension for workflow reconfigurations initially proposed in [BGR08] in section 2. We describe the main concepts of SRML, with respect to STPOWLA in section 3.…”