Kazuyuki Shudo

Overlay Weaver: An overlay construction toolkit

A layered model of structured overlays has been proposed and it enabled development of a routing layer independently of higher-level services such as DHT and multicast. The routing layer has to include other part than a routing algorithm, which is essential for routing. It is routing process, which is common to various routing algorithms and can be decoupled from a routing algorithm. We demonstrated the decomposition by implementing an overlay construction toolkit Overlay Weaver. It facilitates implementation of routing algorithms and we could multiple well-known algorithms just in hundreds of lines of code with the toolkit. The decomposition also enables multiple implementations of the common routing process. Two implementations the toolkit provides perform iterative and recursive routing, respectively. Additionally, to our knowledge, the toolkit is the first feasibility proof of the layered model by supporting multiple algorithms and the higher-level services. Such modular design contributes to our goal, which is facilitation of rapid development of realistic routing algorithms and their application. We demonstrates that Overlay Weaver supports the goal by conducting large-scale tests and comparisons of algorithms on a single computer. The resulting algorithm implementations work on a real TCP/IP network as it is.

Constructing Grid Applications Using Standard Grid Middleware

The effectiveness of standard Grid middleware has been evaluated through the work of “gridifying” a legacy program. As a case study, we have gridified a typical parameter survey program called barotropic S-model which aims to predict short- to middle-term weather change accurately. Ninf-G was used to gridify the system. It was found that the program could be easily gridified using Ninf-G without worrying about the complicated structure of the Grid itself. Performance was measured on the ApGrid Testbed which spreads over Pan-Pacific countries. Although large costs of initialization and termination hinder the application from attaining good performance, these costs can be reduced by optimizing the middleware as well as the application itself. Using over 100 processors, we succeeded in giving a demonstration of a weather prediction simulation at the CCGrid conference, PRAGMA workshop, and SC2003 conference. Lessons learned from the construction of the demonstration system are presented.