中文摘要：

针对服务放置问题，提出P2P覆盖网络框架下自上而下的两级服务部署策略，研究领域内部服务部署的优化模型和求解算法。仿真实验结果表明，领域内部服务放置策略能降低领域内部服务组合的代价，两级服务部署策略从整体上减小了用户获得组合服务的总代价。

英文摘要：

A two-tier service placement strategy based on the P2P overlay network framework is proposed. The optimization model is built for intra-domain Service Placement Problem（SPP） and an efficient algorithm is designed to solve the problem. Several cost calculation methods are adopted to fit different structures of the composed service. Simulation result shows the intra-domain service placement strategy decreases the cost for intra-domain composed services, and the two-tier service placement strategy decreases the total cost of composed services.