Towards increased expressiveness in service level agreements

The aim of this paper is to argue for the benefits of increased expressiveness in service level agreements (SLAs). Such benefits may be obtained from the use of analytical expressions to specify a SLA’s agreement terms as functions and not as variable or constant values or ranges. The main idea behind this thinking is that functions may contain variables defined in the SLA or be drawn from the known set of reference variables, such as wall-clock time, job start time, current bandwidth of the resource, etc. Experiences and conclusions drawn are in the context of SLA-based job management systems. We demonstrate that the use of analytical expressions in SLAs can potentially reduce the overheads associated with job renegotiation and/or reduce the number of failed agreements. Copyright c © 2006 John Wiley & Sons, Ltd.