Guidelines for the development of resilient web services to enhance business process continuity

Abstract

Processes, either in scientific or business domains, are in general subjected to decay. In general, processes often interact with external components, which are located outside of the process boundaries. Web Services have become the de facto standard for realizing remote software components. Thus, Web Services are often part of a process and therefore can have a strong impact on a correct process execution. However, processes themselves are designed for long lasting, whereas Web Services have a highly dynamic and varying nature. That means, their functional behaviour often changes on demand. That dilemma of volatile third party resources is a major driver for process decay. Business Continuity Management (BCM) is a framework for developing and implementing Business Continuity within an enterprise including various activities like risk management and process analysis. However, Business Continuity plans and strategies do not cover external artifacts sufficiently. Such external services involve a potential risk, but are hard to address by BCM as they are out of the sphere of influence. This thesis analysis reasons why Web Services so easily become outdated. Based on a literature survey, the most common service changes scenarios causing the Web Service's dynamic nature are presented. In a first step we investigate challenges regarding Web Service's resilience. Therefore, we observe the Web Service beyond its public interface to identify non apparent challenges. In more detail, we concentrate our effort on two major challenges: Web Service version management and Web Service dependency management. We organized our work as follows: In the first step, theoretical concepts including requirements and policies addressing the resilience challenges have been developed. In a second step, we provided a reference implementation for that framework to support resilient Web Services. Both, the theoretical and practical contributions lead to the Resilient Web Service Framework. By applying this framework, it supports Web Service providers in offering resilient Web Services. For the purpose of demonstration, we applied the Resilient Web Service Framework on a selected set of scenarios of the Web Service management domain. The introduced resilience annotations get automatically attach to the service's WSDL. It demonstrates the successfully capturing of Web Service's dependencies at runtime. Furthermore, notifications have been pushed in case of a dependency modification.