Abstract

Abstract-Web services paradigm is allowing applications to electronically interact with one another over the Internet. The business process execution language (BPEL) takes this interaction to a higher level of abstraction by enabling the development of aggregate Web services. However, the autonomous and distributed nature of the partner services in an aggregate Web service present unique challenges to the reliability of the composite services. In this paper, we present an approach where existing BPEL processes are automatically instrumented, so that when one or more of their partner services do not provide satisfactory service (e.g., because of a service being overwhelmed, crashed, or because of a network outage), the request for service is redirected to a proxy Web service, where the failed or slow services are replaced by substitute services.

Web services are increasingly being used to expose applications over the Internet. These Web services are being integrated within and across enterprises to create higher function services. BPEL is a workflow language that facilitates this integration. Although both academia and industry acknowledge the need for workflow languages, there are few technical papers focused on BPEL. In this paper, we provide an overview of BPEL and discuss its promises, limitations and challenges.

Abstract. Grid computing aims to create an accessible virtual supercomputer by integrating distributed computers to form a parallel infrastructure for processing applications. To enable service-oriented Grid computing, the Grid computing architecture was aligned with the current Web service technologies; thereby, making it possible for Grid applications to be exposed as Web services. The WSRF set of specifications standardized the association of state information with Web services (WSResource) while providing interfaces for the management of state data. Key to the realization of the benefits of Grid computing is the ability to integrate WS-Resources to create higher-level applications. The Business Process Execution Language (BPEL) is the leading standard for integrating Web services and as such has a natural affinity to the integration of Grid services. In this paper, we share our experience on using BPEL to integrate, create, and manage WS-Resources that implement the factory pattern. We use a Bioinformatics application as a case study to show how BPEL can be used to orchestrate Grid services. The execution environment for our case study comprises the Globus Toolkit as the Grid middleware and the ActiveBPEL as the BPEL engine. To the best of our knowledge, this work is among the handful approaches that successfully use BPEL for orchestrating WSRF-based services and the only one that includes the discovery and management of instances.

No abstract