Usage Scenarios to be included in the spec.

• 2.1 Reserving More Resources. Consider a case in which a service provider (also the agreement responder) provides a hosting service. A service consumer, a web ticketing site, had requested the hosting service in order to sell concert tickets. The sales amount is growing and the service consumer decides that it needs more web server resources. Since the service consumer does not want to suspend the service while the new agreement is being made, the service consumer (Agreement Initiator) decides to renegotiate for more web servers and sends an agreement modification request to the service provider (Agreement Responder). Depending on the available resources, the service provider agrees / disagrees to adding more resources.

• 2.2 Extension of Agreement Expiration Time Consider a case in which a service provider (also the agreement responder) provides a hosting service. A service consumer, a web shopping site, had requested the hosting service in order to sell a new merchandise. Originally the request had been for a certain period. After that duration, the original intention had been to terminate the contract. Thus, the expiration time of the agreement had also been set to a certain date. Later on, it turns out that the sales amount of the merchandise is much more successful than had been expected. Thus the service consumer decides that it would like to extend the service. Since the resource needs had been the same as before and the service consumer didn’t want to suspend the service while waiting for a new agreement to be made (Also the hosts would be undeployed and might be re-deployed in a different environment) the service consumer (Agreement Initiator) decides to renegotiate for a longer usage period modifying the usage time defined in a service description term as well as the extending the expiration term. An agreement modification request is sent from the agreement initiator to the agreement responder. Agreement responder is happy to extend the deal so creates a modified Agreement and sends the EPR of the new agreement to the agreement initiator as an acceptance message.

• 2.3 Asking for Releasing Resources which had been Agreed Upon (Thanks to Dominic Battré) Consider a case in which a service provider (also the agreement responder) provides a hosting service. A service consumer, a web shopping site, had requested the hosting service in order to sell a new merchandise. The service had been agreed upon and is being serviced. Due to unforeseen reasons (A higher priority service consumer requests for more resources. / Due to server problems, some of the resources has to be allocated to other currently running services./ The power company forecasts that it would not be able to comply to the necessary power consumption and asks for the service provider to reduce power usage etc..) the service consumer (Agreement responder) realizes that it will not be able to meet the SLA level that had been agreed upon. So the service provider sends an urgent agreement modification request to the service consumer (Agreement Initiator) to lower the agreed upon SLA with reduced cost for the service initiator. Service consumer agrees/disagrees on the agreement modification depending on how much priority it has and the advantage of the reduced cost.