The Web services resource framework defines conventions for managing state in distributed systems based on Web services, and WS-notification defines topic-based publish/subscribe mechanisms. We analyze five independent and quite different implementations of these specifications from the perspectives of architecture, functionality, standards compliance, performance, and interoperability. We identify both commonalities among the different systems (e.g., similar dispatching and SOAP processing mechanisms) and differences (e.g., security, programming models, and performance). Our results provide insights into effective implementation approaches. Our results may also provide application developers, system architects, and deployers with guidance in identifying the right implementation for their requirements and in determining how best to use that implementation and what to expect with regard to performance and interoperability.

Grid applications can combine the use of computation, storage, network, and other resources. These resources are often geographically distributed, adding to application complexity and thus the difficulty of understanding application performance. We present GridMapper, a tool for monitoring and visualizing the behavior of such distributed systems. GridMapper builds on basic mechanisms for registering, discovering, and accessing performance information sources, as well as for mapping from domain names to physical locations. The visualization system itself then supports the automatic layout of distributed sets of such sources and animation of their activities. We use a set of examples to illustrate how the system can provide valuable insights into the behavior and performance of a range of different applications.