Towards a Protocol for the Attachment of Semantic Descriptions to Grid Services

Service discovery in large scale, open distributed systems is difficult because of the need to filter out services suitable to the task at hand from a potentially huge pool of possibilities. Semantic descriptions have been advocated as the key to expressive service discovery, but the most commonly used service descriptions and registry protocols do not support such descriptions in a general manner. In this paper, we present a protocol, its implementation and an API for registering semantic service descriptions and other task/user-specific metadata, and for discovering services according to these. Our approach is based on a mechanism for attaching structured and unstructured metadata, which we show to be applicable to multiple registry technologies. The result is an extremely flexible service registry that can be the basis of a sophisticated semantically-enhanced service discovery engine, an essential component of a Semantic Grid.

Towards a Protocol for the Attachment of Metadata to Service Descriptions and its Use in Semantic Discovery

Service discovery in large scale, open distributed systems is difficult because of the need to filter out services suitable to the task at hand from a potentially huge pool of possibilities. Semantic descriptions have been advocated as the key to expressive service discovery, but the most commonly used service descriptions and registry protocols do not support such descriptions in a general manner. In this paper, we present a protocol, its implementation and an API for registering semantic service descriptions and other task/user-specific metadata, and for discovering services according to these. Our approach is based on a mechanism for attaching structured and unstructured metadata, which we show to be applicable to multiple registry technologies. The result is an extremely flexible service registry that can be the basis of a sophisticated semantically-enhanced service discovery engine, an essential component of a Semantic Grid.

A security architecture for a semantic Grid registry

Existing registry technologies such as UDDI can be enhanced to support capabilities for semantic reasoning and inquiry, which subsequently increases its usability range. The Grimoires registry was developed to provide such support through the use of metadata attachments to registry entities. The use of such attachments provides a way for allowing service operators to specify security assertions pertaining to registry entities owned by them. These assertions may however have to be reconciled with existing registry policies. A security architecture based on the XACML standard and deployed in the OMII framework is outlined to demonstrate how this goal is achieved in the registry.