Hi all, I am happy to see this discussion. Let me state my position in two steps: Wearing my researcher hat and my OGSA-RSS-Cochair hat. As a researcher, I think we need advance reservation in grids for a huge class of jobs. I would like to have an agreement between the client/consumer and the provider/producer for each job (possibly not for very small tasks). The provider should decide which terms he can offer, and the client should accept or refuse. A scheduler/resource broker has then the duty of bringing clients and provider together. There is no such thing as atomicity in distributed systems, therefore I would like to have an economic model that punishes participants that violate any contracts. Basically, since the provider needs to execute a given job, he needs to know the dependencies of a job and may then map the job to a set of local resources, or start provisioning of resources. The broker gathers offers from various providers, which consist of multiple properties. The client provides information about his preference structure. The broker is then responsible for matching the offers to the clients needs. The client is then presented with this solution and may confirm it. If one of the parties cancels the agreement, the broker should propagate the cancelation cost to the entity that caused the cancelation. As a OGSA-RSS Cochair, I also have to state that this is out of scope. RSS deals with the Execution Planing System (EPS) and the Candidate Set Generator (CSG). As Donal already wrote, there is no change on the environment during the execution of those services. Therefore, the CSG can point to a (ordered) set that may suit the needs of a given job, and the EPS can then choose an appropriate execution location. There is no reservation support at the moment. If the Jobmanager chooses to reserve resources, he is on his own. There is no way of supporting e.g. coallocation of resources in the RSS. But nevertheless, I would love to see a short primer document about WS-Agreement. -Mathias