Analysis And Research On Method Of Service Composition Optimization In Dynamic Networks

With the rapid development of wireless techniques, many portable devices emerged, such as smart mobile phones, wearable devices etc., which enrich our measures to accessing Internet and to make communication. Meanwhile, the Internet based services and applications are exploding, which leads that to efficiently deal with all kinds of requirements in Internet faces huge challenges, especially for the network environment that wireless equipments occupy larger proportion. We call the above network environment as the dynamic networking, in which requirement variety, node mobility and communication resource scarity are its main characteristics. Many existed strategies or techniques in traditional Internet are no longer to applying in dynamic networking. Therefore, this dissertation focus on designing strategies of service optimalization for dynamic networking.In this dissertation, three contributions are made:optimal service routing design, service flow composition and optimal schedule, and lightweight malicious nodes detection strategy and channel protection encryption mechanism.In detail, for the case with controllable mobile nodes, we propose an architecture that efficiently finding an acceptable service composition strategy through moving several nodes. Generally, given the requirements of all arrived services, we firstly compute the set of nodes in the reverse route of the service composition of these services and determine how many feasible routes to support this composition. Then we can use MASCO (Movement-Assited Service Composition Optimization) algorithm to calculate optimum position combination of feasible nodes, and move minimum nodes to calculated positions to complete the service composition. This method can eliminate reverser route loop and reduce computation complexity of determining optimal service compositions.For case with distributed service requirements and variety of services, such as wirless monitoring systems, we propose a dynamic service composition method which may satisfy all requirements as much as possible and alleviate transmission collision of tasks through dealing all kinds of services differently and locally. We adopt the SLA (Service Level Agreement) mechanism and design fleasible SLA definition. In our system, any service requirement has its SLA attribute which determine its priority to be served, we attempt to satisfy all requirements if the resource is sufficient. A SLA based flow schedule strategy is presented, the experiment results show the transmission collision probability is decreased, the system throughput and experience quality is increased.For the disadvantage in mobile wireless networking that all routing may tolerant larger delay, which may incur malicious attack for working energy limited nodes. We propose a lightweight encryption mechanism KMDTAN (Key Management for Delay Tolerant Ad hoc Networking), which may help normal nodes detect malicious nodes immediately through judging received key. The encryption mechanism is infrastructure free, and just need simple verification between communication peers. As a result, the life of the service network grows drastically and ensure high dependability of given the service composition strategies. Experiment results show the malicious nodes detection rate is increased.