In order to achieve adaptive and efficient service composition, a task-oriented algorithm for discovering services is proposed. The traditional process of service composition is divided into semantic discovery and functional matching and makes tasks be operation objects. Semantic similarity is used to discover services matching a specific task and then generate a corresponding task-oriented web service composition （TWC） graph. Moreover, an algorithm for the new service is designed to update the TWC. The approach is applied to the composition model, in which the TWC is searched to obtain an optimal path and the final service composition is output. Also, the model can implement realtime updating with changing environments. Experimental results demonstrate the feasibility and effectiveness of the algorithm and indicate that the maximum searching radius can be set to 2 to achieve an equilibrium point of quality and quantity.
为各类飞行器提供互联网接入的主要技术方案可以分为卫星通信和地空宽带2种。当飞行器处于两者的重叠覆盖区域,采用多路径进行数据通信将有可能极大改善传输性能。针对上述飞行器多接入场景,该文提出了一种多路径传输优化方案DMPTCP(dynamic multipath transmission control protocol)。针对链路通断情况发现缓慢、数据分配效率低的问题,结合飞行轨迹可预测的特点,设计了一种基于链路通断状态预测的数据分配算法;并针对链路时延和丢包率差异大所导致的接收方乱序情况严重的问题,通过接收方同时在多条子流回复连接层否定确认信息,使得发送方能够快速获得接收方总体乱序情况并对丢包进行重传。仿真实验表明:DMPTCP在聚合带宽和接收方总体乱序情况两方面均明显优于现有多路径传输机制。
