E-service/process composition requires allocating suitable resources to a set of services that constitute a composite service/process. The problem is complicated due to undetermined constraints of each component service and unpredictable solutions contributed by service providers. It needs the ability to rapidly identify the suitable solutions as well as effectively coordinate them under various constraints. In this paper, an agent-mediated coordination framework for e-service/process composition is proposed. Each agent works as a broker for each service type, posting service constraints, searching suitable solutions and refining the constraints for achieving coherence among the decisions of each service. Based on the framework, a prototype of multi-agent supported e-supply chain composition is implemented. The experimental results indicate the significant effectiveness of the approach.