Improving workflow execution through SLA-based advance reservation

In SOA-based Grid environments service provider and service consumer usually do not know each other. In order to establish a business relation they must inter alia (i) create a trust relationship, and (ii) set up mechanisms to create reliable, verifiable, and, at least in a commercial environment, also audible agreements with respect to the services requested, delivered and consumed. In this paper we will only briefly address (i) but concentrate on solutions for (ii) based on Service Level Agreements (SLAs). Therefore we will give an overview on the state-of-the-art of SLA usage in Grids, highlight possible obstacles for the deployment of SLAs, and present a detailed example of a service improving the execution of workflows through the use of WS-Agreement to negotiate advance reservation of resources to execute workflow components.