摘要： 分析了在Overlay服务网络上进行服务组合的必要性，指出了在进行组合时服务次序约束所带来的特定困难，进而给出了服务次序约束的形式化定义以及带OoS组播路由问题的数学优化模型。借助于罚函数的方法，将服务次序约束条件吸收到目标函数中，从而可以用求解一般组播优化模型的算法来求解新模型。

关键词: Overlay服务网络, 服务次序, 组播, 罚函数方法

Abstract: This paper analyzes the necessity for combining services and the particular difficulties considering order of service constraints, and proposes the formal definition of order of service (OoS) and a programming model for multicast routing problem with OoS-constraints in the overlay network environment. Penalty-function method is employed and the OoS-constraints are integrated into the objective function, resulting in that many algorithms for general multicast model can be used to solve the proposed OoS-multicast model.

Key words: Overlay service network, Order of service (OoS), Multicast, Penalty-function method