| Instant Messaging (IM), a new kind of technology that can enable us to recognize online users and exchange information with them instantly. It is a very popular instant-communication method and such kinds of products are Skype, QQ, Gtalk and so on. IM is based on the technology of internet, wired and wireless network. IM is a kind of terminal service that can support the user's online instant massaging, enable two or more users to transmit test, picture and voice information through the internet and enable us to send and receive internet message instantly. Compared with the traditional Email service, IM is more convenient than telephone and can save a lot of time when transmitting information. All of those features make IM become the new symbol of modern information exchange method.The system introduced in this dissertation is designed by JinGang Computer Network Co. Ltd in Jilin province. Although it's a kind of instant messaging software, the system can also provide a solution used for virtual private network. Based on the UDP protocol, such kind of solution can complete the data transmission work by using P2P technology. Meanwhile, the virtual adaptor driver based on TAP/TUN pattern can provide the enterprise and the further third application with Seamless compatibility. All of those methods can ensure the seamless migration on the virtual network of existing business. Future more, it also can solve the problem of special service program so that further third application can steadily run on the virtual network.Virtual adaptor and P2P technologies are applied in this system. In terms of the operation system, the driver program for virtual adaptor is just like a real physical network adaptor so that the operation system can control it as a physical network adaptor. By using virtual adaptor technology, the project can have a great improve in compatibility, stability and characteristic of easy-use. All of those mentioned above can't be found in existing solution and the system can provide the customer the best experience.The P2P technology originated from the primary network communication. It refers to a fully distributed system, whose nodes are identical in the terms of function and assignment. The P2P pattern changes the service mode and transmission path in the traditional mode.Compared with the client/server mode, it has no central server and the function of server and data distribution are located in the nodes, which have the function of implementing the distribution of activities and allocation of tasks to the other nodes. It is a fully distributed architecture and every of such entities in the network are in the same status. All of them can request access to service and provide service synchronously. They play dual roles of server and clients in the traditional mode and can even have the function of router and high-speed cache. Such entities in the network constitute the vertex-connected graph and they also can directly exchange information between each other. The problems of server-dependent and IP address-dependent will also successfully be solved and the performance of the system can be improved by using the P2P technology.Through the combinations of the P2P, virtual adaptor, announcement of network events technologies, the system designed in this dissertation constructs a unique model of a virtual private network. Thus this kind of mode synthesizes the superiorities of the P2P, virtual adaptor and announcement of network events technologies. The competitiveness of the company's products can have a great improve and better social benefits can also be created for the customers through the integration of the system with the company's existing products. In the handling of instant messaging, the system simply posts the relevant network events and deal with the interested events by using these outstanding characteristics provided by the bottom layer. The IM part no longer cares about the problem of data transmission and Internet penetration so that it simplifies the development difficult of the application. Generally speaking, by using a circular network technology, the application can concentrate on business, and the services deal with Collaborative work.The significances for the development of this system are listed as follows. Firstly, it can meet the increasing demands of the clients and reduce the information costs of enterprise. Secondly, it can save inputs on network building, everyday maintenance and information security and the enterprise's level of information and safety can also improved a lot. The system enables the development of business applications in the existing platforms and models to develop without repeating the input, and meet the needs of collaboration. Therefore,It is convinced by the JinGang Company that the platform can win more customers, effectively reduce the operating costs, enhance the level of competitiveness and profit with a good cost-effective and market prospects.The system designed in this dissertation can be divided into two parts. One part is server-side, which mainly provides the service of authentication and data storage to the customers by store the relevant data into database. The other part is client-side, the core of this project. The client-side is consisted of four parts. The first part is application layer, which contains all kinds of services (instant messaging also included) that depend on bottom layer's virtual network. The second part is virtual adaptor driver. The virtual adaptor driver can provide an important guarantee for the good compatibility so that the project can become the standard network application program. The third one is client service. The main work of this part is listed as follows: log in and obtain the relevant parameters, complete the transmission of the virtual network data, provide various interfaces services to the upper applications. And the last part is physical network. It directly connects to the internet and realizes data transmission between different nodes.In this dissertation both of the backgrounds of system and the concept & origin of the instant messaging were introduced in the beginning. Meanwhile, the development trends of the further IM software and typical instant messaging system in home and aboard were introduced. Further more, the relevant technologies, including the technical definition, structure, application of P2P and virtual adaptor were also described in details. Thus the necessary for the use of virtual adaptor technology were gained. In this dissertation, the overall structure of the system was designed and the system architecture, the design of database, the character and function of the system were discussed in details. The author also analyzes the functional package designed for bottom communication, including network events announcement, sending queue module, conversation module, network transmission module, transmission management module and handshake module. Meanwhile, the operating interface and functional effect map were showed in the dissertation. A summary about the system and vision for the future were given in the end of the dissertation. The client service will send the data that is received from a virtual card data through standard Sockets interface to the remote client service.For the use of relatively new technology, parts of the function and performance need to be improved. There will be some debugs when delivering massive data or very narrow bandwidth and extreme poor performance of the computer are occurred. It is believed that all these debugs will be solved as the products mature slowly. With the development of the JinGang Company, this system designed in this dissertation will gradually gain a firm foothold in the market and have a good future. |
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