Service Level Agreements (SLAs) have been promoted as a means to forge agreements between users and providers of services. These agreements could specify acceptable constraints for the provision of services. These constraints can be used by providers to optimize the use of their resources and at the same time from users to obtain better deals from the providers. Managing the SLAs is a challenging task from the provider's point of view, as SLAs may increase pressure on their resources.
There are various optimization problems, for some indication of past research in the area, I could point to: http://www.gridscheduling.org