Improving the Scalability of DPWS-Based Networked Infrastructures

The Devices Profile for Web Services (DPWS) specification enables seamless discovery, configuration, and interoperability of networked devices in various settings, ranging from home automation and multimedia to manufacturing equipment and data centers. Unfortunately, the sheer simplicity of event notification mechanisms that makes it fit for resource-constrained devices, makes it hard to scale to large infrastructures with more stringent dependability requirements, ironically, where self-configuration would be most useful. In this report, we address this challenge with a proposal to integrate gossip-based dissemination in DPWS, thus maintaining compatibility with original assumptions of the specification, and avoiding a centralized configuration server or custom black-box middleware components. In detail, we show how our approach provides an evolutionary and non-intrusive solution to the scalability limitations of DPWS and experimentally evaluate it with an implementation based on the the Web Services for Devices (WS4D) Java Multi Edition DPWS Stack (JMEDS).Comment: 28 pages, Technical Repor

Towards flexible compensation for business transactions in Web service environment

Recently, many business applications embrace Web services as their implementation technologies. Due to the long duration and loosely coupled properties, Web service based applications require more transactional supports beyond traditional transactions. Some initial work has been done to deal with the transaction aspect of Web service applications, in form of standards or protocols. Among these efforts, compensation is commonly used for backward recovery. However, the compensation mechanism adopted is too fixed and cannot satisfy the various requirements of different applications. In this paper, we propose a flexible compensation mechanism which enables flexible compensation schemes for a single failed case. Based on a thorough analysis of current Web service compensation protocols and standards, we extend the flexible compensation mechanism to the Web service computing environment. The implementation of the extended compensation mechanism is discussed and the incorporation of the mechanism into current standards is also addressed