A Study On Service Quality Optimization Methods On Internet Of Things System

The Internet of Things(IoT)is an important part of modern information technology.It is a highly integrated and synthetical application of the new generation of information network technology.Also,it is significant to foster new economic growth points,give impetus to industrial transformation and upgrading,and improve the efficiencies and effectiveness of social management and public services.IoT service is used to solving the problems of resource integration,resource reuse and interoperability between heterogeneous components,which applies the service-oriented methodology to the internet of things.It is an extension of the sensor network to the physical environment.More precisely,it allows heterogeneous physical facilities,as well as the physical facilities and traditional Web services,to invoke and exchange information to achieve seamless integration between the physical world and the virtual network world.However,compared with traditional Web services,IoT services have their own characteristics.First,although there are abundant functional equivalent of services on IoT,due to the openness,complexity and dynamics of its environment,and the stochastic uncertainty of Web services,it is difficult for users to obtain a high quality service composition.Second,a large number of service providers exist in the Internet of Things,but their credibility cannot be guaranteed.All of the participants in the service portfolio have the possibilities of bringing malicious attacks,fraud and false information.As a result,how to ensure the credibility is the challenge of IoT services.Third,most of the Internet of Things services interact with each other through physical devices.The working environment often has the characteristics of autonomous changes.Fourth,IoT services are affected by the time constraints of the physical environment,resource constraints,and potential failure probability of the devices.Therefore,the response speed,service energy consumption,and fault tolerance of IoT services have become an important factor affecting the overall performance of the Internet of Things system.In summary,how to effectively solve the service composition of IoT services and improve service quality,has become one of the important research contents in the field of IoT services.To address the above issues,this dissertation aims to improve the quality of IoT services and investigate the characteristics of the Internet of things in terms of service evaluation,selection,combination and optimization.The major contributions are summarized as follows:(1)Considering the complexity,uncertainty and randomness of IoT services,we introduce complex network theory into the field of IoT services.Based on the methodology of complex networks,we construct a complex network model for IoT services.Then,with the help of this model,we analyze the characteristics of IoT services.This above steps establish foundation to improve the quality of service composition.(2)The credibility of Internet of things service providers is one of the important factors affecting service quality.In this dissertation,we apply the credibility evaluation method of social network to the Internet of Things service field.The credibility of the IoT service provider is evaluated based on the constructed IoT service network model.Furthermore,we propose an evaluation method for IoT service credibility.Based on the method,a trust-based service optimization selection method is given.In this manner,we select a highly credible Web service as a candidate for a service composition,which ensures the credibility of the IoT service and improves its quality.(3)Based on the concept of service-based adaptive software system,we propose a multi-mechanism adaptive service environment optimization method combining the dynamic change characteristics of IoT service users with the uncertainty of service environment.The method constructs an optimal service environment for recommending replaceable services by pre-calculating the execution path.And then divides the service optimization mechanism into two parts:offline and online optimization.This approach reduces the calculation cost and improves the efficiency of the service combination.(4)We propose a multi-tenancy SaaS service model based on interaction and state transition for the Internet of Things environment.With the aid of the SaaS service model and the characteristics of the Internet of Things,the prototype system of the human service manager is given,in which the Human Service Manager functionality are reconnected and integrated into a new functional model.Furthermore,using the state manager,interactive executor and manual service manager,it realized the interaction between the two parties.To support the rapid and efficient development and deployment of SaaS software,we design a session-oriented service interactive execution engine based on the model,which can support the efficient concurrent execution of SaaS software under multi-tenancy and multi-user conditions.