Grid and Web Services to converge

Speccing out

The two big computing ideas of the twenty first century grid computing and web services were brought closer together by an announcement this week at GlobusWorld the grid conference run by Globus Alliance, writes Bloor Research analyst Peter Abrahams.

The Globus Alliance is a research and development project focused on enabling the application of Grid concepts to scientific and engineering computing and has developed the toolkit used by most scientific and university grid computing projects. It is an alliance between several university and laboratories in the US and Europe, including Edinburgh.

Web services have concentrated on creating an environment for 'applications on-demand' whereas grid has concentrated on providing 'computer-resources on-demand'. The announcement is made up of two new web services specifications that are necessary to make the grid computer resources available to the applications without the applications having to be grid aware. The two are the WS Resource Framework and the WS Notification specifications.

Note the careful use of the word specification, and not standard, they are specifications put out for public discussion before they are submitted to a standards body. The authors of the specification say that they will submit them to a standards body soon. A word of caution IBM and Microsoft said that when they announced their WS Reliable Messaging specification nearly a year ago and there is still no indication when WS-RM will be submitted. The new specification use WS-RM as a building block so I await movement in this area. IBM is one of the main authors of the new specification whereas Microsoft is not involved, so movement may be faster.

WS Resource Framework specification was contributed to by IBM, Globus and HP. It defines how to access a WS Resource through a web service. A web service is stateless whereas a WS Resource is stateful, the state could be such things as data in a purchase order, current usage agreement for resources on a grid, or metrics associated with work load on a Web server. The framework describes a standard way to access a WS resource by referencing it through an endpoint reference made up of the web services address and a resource id. It also defines how a web service can access or create new WS resources.

The WS Notification specification was contributed to by IBM, Globus, Akamai, HP, SAP, Tibco and Sonic. It provides a publish-subscribe messaging capability for Web Services. It enables changes or events to be published in a standard way and then notification send directly or via a broker. This is bringing some of Sonic's Enterprise Service Bus (ESB) concepts into a standards specification.

WS Notification is important for grid computing because it provides a standard way for grid resources such as web servers to notify grid schedulers of changes in state. Changes in state include coming on and off stream, being fully loaded or having spare capacity, having a fault that needs attention etc. All of this information is required for a grid scheduler to make informed decision on what resources to use next.

With well defined WS Resources being accesses through well defined Web Services it is possible for grid resource to be scheduled without the application having to be grid aware.

If IBM. HP and Globus can take these specifications quickly to a standards body then there is a high chance that the rest of the industry including integration, system management and application systems suppliers will support the standards in their products.

© ENN

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