Getting To GRIPs With Grid Interoperability

Grid computing is one of the hot topics in distributed computing. Using a Grid of computers, located around the world, it is possible to carry out truly massive calculations. To achieve this requires a high level of interoperability between computer systems. Addressing this is IST project GRIP. Its system will be used to enable the European Weather services to share resources and allow applications the resources for which are beyond the capabilities of a single service.

Grid computing is one of the hot topics in distributed computing. Using a Grid of computers, located around the world, it is possible to carry out truly massive calculations. To achieve this requires a high level of interoperability between computer systems. Addressing this is IST project GRIP. Its system will be used to enable the European Weather services to share resources and allow applications the resources for which are beyond the capabilities of a single service.

“Grid computing is about defining and prototyping standards that enable the sharing of distributed resources, such as remote data, remote computer applications, remote instruments, output media, and so on,” says Dietmar Erwin, GRIP project coordinator, from Germany’s Zentralinstitut für Angewandte Mathematik (ZAM) at the Research Centre Jülich. “To access these resources on a particular system, however, may require detailed specific knowledge of that system, and the next system may require an entirely different knowledge set.” There is an obvious need for standardisation in this area.

A lot of development work has already been carried out on various software solutions. In the United States, a toolkit has been developed, called Globus, that enables application developers and middleware developers to use the Grid, and its resources, in a consistent way. “You can visualise this as a kind of horizontal approach,” adds Erwin, “which covers the areas that have to be addressed. It provides application programming interfaces [APIs] to high-level services that will make use of Globus program calls.”

In Germany a different approach was taken called UNICORE (UNiform Interface to COmputing Resources). It’s a vertically-integrated Grid system that starts with the user’s desktop and a graphical interface. It enables the user to formulate complex computational problems that may involve many computers at many different sites. UNICORE has many high-level features, such as the control of repetitive jobs and error handling. “You can define your computational tasks, submit them to the Grid for execution and monitor their progress – without having to sit at a particular console on each of the systems,” explains Erwin.

Searching for molecules

“The idea behind GRIP was to combine the advantages of the two Grid developments: the seamless access to resources of UNICORE and the wide support that already exists for Globus,” says Erwin. “In the first year of the project, we successfully completed our objective of making Globus resources accessible from the UNICORE interface. This was done by extending some of the components within UNICORE and without having to modify Globus in any way. We demonstrated various applications in the meteorological field and molecular science applications. Our GRIP partners in Warsaw use GRIP for bio-molecular calculations and on a regular basis. Especially for CPMD (Car-Parrinello molecular dynamics), a graphical interface for performing certain molecular computations has been developed in UNICORE that even a novice can use. The point is that users are no longer constrained to using only locally available applications. So long as UNICORE or Globus have been installed, there is no difference in the user interface.”

Complying with Open Grid Service Architecture

Part of the original GRIP plan included work to make UNICORE resources available from Globus, i.e. in the reverse direction. “This was an entirely logical and consistent objective, but then events overtook us,” comments Erwin. “The Global Grid Forum started work on the definition of OGSA (Open Grid Service Architecture), so it became much more important to focus our resources on interoperability between UNICORE and Globus Toolkit 3. The latter is essentially Globus with an OGSA wrapper around it, and complies with the Open Grid Service Architecture. The OGSA standard is in the process of being defined, so obviously we were not able to complete the task within the original timeframe. The upshot of this modification to our original work programme is that we will be able to interface any UNICORE-based Grid system with any Globus- or an OGSA-based system.”

The project strategy to make UNICORE OGSA-compliant has led to UNICORE’s selection as Grid middleware by the Japanese Grid Initiative at the Global Grid Forum (GGF7) in Tokyo last spring. The initiative plans to build an infrastructure making over a hundred Teraflops available for scientific applications.

Another high-profile use of the GRIP system will be to provide the framework for combining the computing resources of the European weather services for extended range and probability weather forecasts. The resources available to an individual service are insufficient to tackle such problems but by sharing their resources the community together will be able to provide better weather guidance.