Overlay-network Based Distributed Interactive Application And Key Tecknologies

Human society is a social community, communication and collaboration are the foundation of human social activities. Human beings is put into the information age by Sustained and rapid development of network and computer related technology. Computer applications shift from single-user mode to multi-user collaborative model in information age, no longer confined to a separate stand-alone system, but carried out in distributed form. Interactive applications between people and computer become interactive applications based on Internet, that is, DIA(distributed interactive application). DIA-based communication and collaboration in information age can improve efficiency, promote the development of productive forces, improve people’s work and life.Overlay Network is positively concerned and has made extensive development, because of its scalability, flexibility, robustness, ease of deployment and other characteristics. Overlay Network technology is a method of network configuration, regardless of the specific network level and specific technology. According to actual needs, it is to construct a virtual logical network based on the original physical network. In the maximum compatibility with the existing network, Overlay Network supports features and services that original network is difficult or impossible to provide. Therefore, Overlay Network can provide a more flexible solution to the existing network architecture problems.This paper studies scalable distributed interactive application based on DIA research status and characteristics, starting from the network architecture. The idea of Overlay Network is integrated into DIA study, and the scalability and adaptability features of Overlay Network are used. In order to achieve large-scale deployment of DIA, DIA is studyed based on Overlay Network to overcome DIA past deficiencies in architectures and mechanisms. Therefore, considering DIA scalability, low latency, high bandwidth, dynamic, many-interaction and other needs, this paper propose the concept of DIA based Overlay Network and network architecture ODIA(Overlay-Network based Distributed Interactive Applications), and key technologies based on ODIA were studied.1. DIA network architecture based on overlay network is studied.Based on the analysis of traditional DIA network architecture, it is proposed the concept of DIA based on Overlay Network and the logical framework of network architecture model ODIA. ODIA is functionally divided into three layers,namely DIA user application layer, ODIA overlay layer and physical network layer, and the function of each layer and relationships is defined. The construction of DIA overlay layer based on Overlay Network is detailed descripted, and a hierarchical structure overlay network model DIA service domain layer—DIA core layer is put forward. Combining DIA features and texisting physical network characteristics to construct ODIA. Based on delay distance and application field correlation between ASes, the network is divided into K DIA service domains. Each DIA service domain contains one or more autonomous domains, and certain proxy nodes are requisitioned and deployed in a DIA service domain. Service domain layer which support DIA in DIA service domain is generated by the proxy nodes. At the same time, in order to support inter-domain DIA, one or more kernel proxy nodes selected in each DIA service domain to generate DIA core layer. Then, key issues to be addressed are identified in the hierarchical ODIA model.2. It is studied the construction of ODIA overlay layer of network architecture based on Overlay Network.It is very critical to construct ODIA overlay layer of network architecture based on Overlay Network. The construction of ODIA overlay layer includes five sub-problems, that is, DIA service domain partitioning problem DSDD, DIA proxy requisition and placement problem DPRP, DIA service domain layer construction problem DSCP, DIA kernel proxies selection problem DKPS, and DIA core layer construction problem.Firstly, addressing DIA service domain partitioning problem DSDD, based on delay distance and application field correlation between ASes, geographical proximity and large application field correlation ASes are divided into a service domain. Then formal description and modeling DSDD, it is proposed to solve the problem DSDD based on improved genetic algorithm DSDD_IGA.Secondly, the different types of servers in an AS are requisitioned to transform into proxy nodes, which provide services for users in an AS together with DIA proxy nodes deployed. Based on formal description and modeling, DPRP_IPSO algorithm is put forward to solve DPRP, ensuring to meet network performance constraint and as small as possible deployment cost.Thirdly, in order to efficiently support DIA in service domain, addressing DIA service domain layer construction problem DSCP, topology-aware DIA service domain layer network is constructed based on GNP network coordinate system, Hilbert space filling curve, Skip Lists and other technologies, modeling DSCP, proposing DE_DSCP algorithm to solve the problem of DSCP.Fourthly, modeling DIA kernel proxy node selection problem DKPS, immune algorithm DKPS_IA is put forward to solve the DKPS problem, selecting kenel proxy nodes to meet maximum bandwidth and minimum network delay.Finally, in order to effectively support inter-domain DIA, addressing DIA core layer construction problem, it is proposed to construct and optimize DIA core layer based on Hypercube. Modeling DIA core layer construction problem, the optimization goal is to achieve minimum total delay, minimum physical link reusability, maximum link minimum bandwidth and maximum total link bandwidth.3. DIA routing problem based on overlay network is researched.According to DIA routing characteristics and properties, the domain and inter-domain DIA routing problem are studied based on the put forward DIA network architecture model ODIA. Firstly, the static routing problem SMSTR within DIA service domain is studied based on multiple shared trees, modeling SMSTR, proposing SMSTR_TSGA algorithm to solve SMSTR. Secondly, DIA dynamic routing DMSTR is researched based on multiple shared trees in DIA service domain, including node joining and leaving algorithms in DMSTR. Thirdly, the inter-domain DIA static routing problem is studied based on Hypercube, and Hypercube multicast routing algorithm HMR_LC is proposed based on local cluster. Finally, inter-domain DIA dynamic routing problem DHMR is studied based on Hypercube, including node joining and leaving algorithms in DHMR.4. DIA interactive problem based on overlay network is researched.In DIA, how to sort events which occurred on two different nodes, and how to determine whether an event may submit the current process is critical. As the network transmission delay heterogeneous, different DIA node receives the order of events is not the same. A DIA node can not regard the received sequence of events as the processing sequence, and can nor regard the smallest timestamp event as a next event to be processed, Because it can not determine whether there is a smaller event timestamps are still transmitted over the Internet, it has not been received.According to the characteristics and nature of interaction problem, DIA interaction problem is hierarchically solved based on network architecture ODIA. For interactive problem in DIA service domain, under the premise of clock synchronization, interactive control method ICM_SE is put forward based on sampling period and event sequence number. ICM_SE can determine the time of the event can be delivered to executive, and effectively solve the problem of interaction on different nodes within DIA service domain due to the inconsistent event processing order.For inter-domain interactive problem, geographically distributed nodes can not be precisely synchronized clocks, and clock synchronization is not available for large-scale wide area network environment.But the time step rate is almost no difference between the nodes. Therefore, the time conversion method is put forward based on time clock relation matrix, and the event timestamp in other DIA service domain can convert to corresponding local DIA service domain timestamp based on this mothod. Then inter-domain interactive control mothod ICM_CRM is put forward. Simulation shows that interactive control method proposed in this paper has a low overhead, scalability, and can effectively reduce the DIA inconsistencies occur. Finally, network congestion and packet lost not be completely avoided, event message not be able to reach the receiving node in acceptable response time node problem, therefore, DIA interactive control repair mechanism is put forward.5. The mechanism of DIA based on overlay network is studied.DIA mechanisms are studied based on ODIA network architecture, mainly including DIA session registration mechanism, DIA node joining mechanism, DIA node leaving mechanism, the interactive mechanism within DIA service domain based on the sampling cycle and event sequence number, and the inter-domain interactive mechanism based on clock relation matrix. At the same time, the formal description of DIA mechanisms are carried out by using the formal tool Petri net, and the models of DIA mechanisms are carried out based on the reachability graph of Petri net, and the correctness and completeness of those models are verified.Finally, this paper summarizes the research work, analyzes the deficiency existing in the paper, proposes some suppositions to the problem needing further studying base on the existing work, and has looked into the distance to the development prospect of DIA.