With the number of e-Business applications dramatically increasing, service level agreement (SLA) will play an important part in Web services. A SLA is a combination of several quality of services (QoS), such as security, performance, and availability, agreed between a customer and a service provider. Most existing research addresses only one QoS metric, and in the case of the response time, the average time to process and complete a job is typically used.

In this paper, we study trustworthiness, percentile response time and availability. We consider all these qualities for a trust-based resource allocation problem which typically arises in Web services applications. We formulate the trust-based resource allocation problem as an optimization problem under SLA constraints, and we solve it using an efficient numerical procedure.