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Service compositions provide a promising way to realize and coordinate automated support for business activities and processes. These business processes and their automated support need to survive in highly volatile market and technical environments. Consequently, many approaches have been proposed to address the issue of flexibility support in business process modeling and enactment. However, it remains a challenge for researchers and practitioners. In this paper we provide a systematic analysis of the requirements for process flexibility in the context of service compositions, and analyze the existing approaches against these set of requirements. Based on this analysis, we draw some general observations and point to some critical issues for future investigation into business process flexibility support in service composition.

The Single-Instance Multi-Tenancy (SIMT) model for service delivery enables a SaaS provider to achieve economies of scale via the reuse and runtime sharing of software assets between tenants. However, evolving such an application at runtime to cope with the changing requirements from its different stakeholders is challenging. In this paper, we propose an approach to evolving service-based SIMT SaaS applications that are developed based on Dynamic Software Product Lines (DSPL) with runtime sharing and variation among tenants. We first identify the different kinds of changes to a service-based SaaS application, and the consequential impacts of those changes. We then discuss how to realize and manage each change and its resultant impacts in the DSPL. A software engineer declaratively specifies changes in a script, and realizes the changes to the runtime model of the DSPL using the script. We demonstrate the feasibility of our approach with a case study.

Abstract-Service oriented architecture plays a prominent role in creating and utilizing business services in enterprise computing environments. The service composers produce value by aggregating lower-level re-usable services, scattered across the internet to create application level services. Web service middleware facilitates in defining service compositions in a comprehensive manner. However, in order to ensure the business viability amidst unpredictably changing business requirements, such compositions may need to adapt during the runtime. Such changes might vary from a minor regulation to a major re-structuring of the IT service composition. However, the complexity of the composition shouldn't increase and the runtime interruptions to the service delivery need to be kept to a minimum. In this paper we introduce ROAD4WS, which is a middleware extension to the popular Apache Axis2 web service engine. The extension brings together the modular adaptive architecture of the Role Oriented Adaptive Design (ROAD) with the web services deployment and consumption capabilities of the Apache Axis2 engine, in order to facilitate deploying adaptive service compositions.