BPMashup: Dynamic Execution of RESTful Processes

1 Introduction While WS*-based Service-Oriented Architecture (SOA) is employed heavily in the enterprise application & integration space, end-user-oriented organizations such as Facebook, Google or Yahoo! adopted the REST paradigm. Web service ecosystems [1] have been established around web service offerings like social networking, where open platforms enable third-party developers to easily leverage the infrastructure provided by the social networks, to build web applications and plugged-in services for a massive user base. Such a web service ecosystem typically comprises a service provider opening up their product public service platform, a set of external value-added-resellers, and a community of users building and sharing customizations [2]. The lower layers of the traditional SOA-based WS* standards stack provide a loosely coupled infrastructure for Web service ecosystems. However, process layers on top of the standards stack introduce a comparatively tight coupling between the process logic and the WSDL interface definition [3], which tends to be brittle. Composition of RESTful web services is usually achieved as lightweight Mashups – focusing on combining data from various sources, or handling events – or by using textual documentation to allow developers to understand processes involved. Traditional process-centric composition methods hardly fit the new paradigm. REST and Resource-Oriented Architecture principles [4] are well established, and have been applied to web-based cross-enterprise business processes [5, 6] as an alternative way of implementing Web services. However, most existing approaches focus on building a RESTful facade to traditional service technologies without fundamentally using the REST principles. In traditional SOA, many approaches have been proposed to extend BPEL, e.g., with adaptation mechanisms using aspect-oriented programming [7] or rules [8]. These approaches still introduce tight coupling between process definition and Web service description. Some approaches [9] use WSDL-like descriptions for RESTful services, which arguably means losing most of the benefits. In contrast, we present BPMashup in this demonstration: a framework that tailors REST principles towards process-aware information systems. BPMashup consists of the previously published server component, RESTfulBP [10], as well as a novel client-side JavaScript library – the Localized Process Execution Engine, LPEE – for executing processes and rendering UI widgets referring to individual service invocations. It has previously been shown that RESTfulBP can improve the adaptability and interop