In a web service environment, such as Parlay X, contracts are agreed between the involved participants to guarantee a reasonable measure of Quality of Service (QoS). A common policy adopted is for contracts to involve only one parameter which places a limit on the number of incoming operation calls. This constraint is expressed as the maximum number of operation calls per second that a source is allowed to request. In this paper, we investigate the impact that different constraints placed on the incoming traffic have on performance and guarantees. By expressing shaping conditions mathematically, analysis can be performed for a scenario which considers hard time constraints. Simulations will be used to investigate scenarios involving soft time constraints.