The myGrid Notification Service

The notification service is the part of myGrid that enables asynchronous delivery of messages between distributed components. It includes features such as topic-based publish-subscribe messaging, push/pull models, asynchronous delivery, persistence, transient and durable subscriptions, durable topics, negotiation of QoS, hierarchical topic structure and federation of services. Some of these features are novel in the area of messaging middleware. A cost evaluation of some of these features indicate that the overhead incurred is justified in terms of compensating benefits gained.

Automated Negotiation Between Publishers And Consumers Of Grid Notifications

Notification Services mediate between information publishers and consumers that wish to subscribe to periodic updates. In many cases, however, there is a mismatch between the dissemination of these updates and the delivery preferences of the consumer, often in terms of frequency of delivery, quality, etc. In this paper, we present an automated negotiation engine that identifies mutually acceptable terms; we study its performance, and discuss its application to a Grid Notification Service. We also demonstrate how the negotiation engine enables users to control the Quality of Service levels they require.

Automated Negotiation for Grid Notification Services

Notification Services mediate between information publishers and consumers that wish to subscribe to periodic updates. In many cases, however, there is a mismatch between the dissemination of these updates and the delivery preferences of the consumer, often in terms of frequency of delivery, quality, etc. In this paper, we present an automated negotiation engine that identifies mutually acceptable terms; we study its performance, and discuss its application to a Grid Notification Service. We also demonstrate how the negotiation engine enables users to control the Quality of Service levels they require.

Recycling workflows and services through discovery and reuse

Scientific workflows are becoming a valuable tool for scientists to capture and automate e-Science procedures. Their success brings the opportunity to publish, share, reuse and repurpose this explicitly captured knowledge. Within the myGrid project, we have identified key resources that can be shared including complete workflows, fragments of workflows and constituent services. We have examined the alternative ways these can be described by their authors (and subsequent users), and developed a unified descriptive model to support their later discovery. By basing this model on existing standards, we have been able to extend existing Web Service and Semantic Web Service infrastructure whilst still supporting the specific needs of the e-Scientist. myGrid components enable a workflow life-cycle that extends beyond execution, to include discovery of previous relevant designs, reuse of those designs, and subsequent publication. Experience with example groups of scientists indicates that this cycle is valuable. The growing number of workflows and services mean more work is needed to support the user in effective ranking of search results, and to support the repurposing process.