Introduction of P2p technology
What is p2p?
Peer-to-peer is called a peer-to-peer connection or peer-to-peer network. P2P technology mainly refers to the information control technology after the hardware is connected, and its representative form is software. P2P originated from the initial networking communication mode. For example, PCs in buildings are interconnected through local area networks, and different buildings are interconnected through remote dialing through modems. Among them, the communication mode based on TCP/IP protocol constitutes the foundation of today's Internet, so from the perspective of basic technology, P2P is not a new technology, but a new application technology mode.
2. Technical introduction
1. Key technologies
P2p is a new application technology based on Internet environment, mainly software technology.
(1) For many computers on the Internet, P2P applications pay more attention to the interconnection of low-end PCs than other applications. They don't have as strong networking ability as servers. At the same time, for the previous P2P application technology, the current hardware environment has become more complicated. In terms of communication foundation, P2P must provide end-to-end positioning (addressing) and handshaking technology on the existing hardware logic and underlying communication protocols to establish a stable connection. The technologies involved are IP address resolution, NAT routing and firewall.
(2) On the application layer, if two Peer represent two different companies respectively, and they have established a connection through the Internet, then one party's information must be recognized by the other party, so the current protocols on data description and exchange on the Internet, such as XML, SOAP, UDDI, etc. , are considered by a perfect P2P software.
(3) Communication must be secure, and encryption technology must be considered.
(4) Other considerations include how to set up the central server and how to control the network scale.
2. Comparison between 2.P2P technology and existing Internet technology
At present, the main technical mode of the Internet is S/C mode, which requires setting up a high-performance computer with strong processing power and large bandwidth on the Internet, cooperating with high-level server software, and then storing a large amount of data on it in a centralized way, and installing diversified service software, which can serve other PCs on the Internet, provide or receive data, and provide processing power and other applications while processing data in a centralized way. For a PC connected to a server and receiving services, this PC is a client, and its performance may be relatively weak. One characteristic of P2P technology is to weaken the role of the server, or even cancel the server. Any two PCs are servers and clients, which are peers.
3.p2p technology is strictly a grid.
Definition of Grid: Grid is the software infrastructure running on the network, and it is the bond and adhesive to connect and integrate different hardware systems, software systems and application systems.
4.P2P technical characteristics
(1) is both S and C. How to express it depends on the requirements of users, and the network application is freely driven by users.
(2) Information flows directly between network devices at high speed and in time, which reduces the cost of transit service.
(3) It constitutes the basis and application of network equipment interaction.
(4) While the network information is decentralized, P2P devices with the same characteristics can form a subnet existing in the Internet, so that the information can be re-centralized in a new way.
Third, technology application.
At present, p2p technology is mainly used in the following aspects:
1. Timely communication: ICQ, OICQ and IP telephone technology.
2. Enjoy documents and other contents * * *-BT technology
Now people are familiar with downloading resources with BT. The full name of BT is BitTorren, which is translated into BitTorren in Chinese. Many netizens call it homophonic, called/abnormal. For example, it is very vivid to remove the derogatory color, because this is indeed a resource exchange mechanism different from the normal Internet. BT, as an innovative download tool, absorbs the technical advantages of P2P and simply and effectively realizes the sharing of download pressure. BT first divides a file into z parts at the uploader's end. A downloads the N part randomly on the server side, and B downloads the M part randomly on the server side, so that A's BT will get the M part downloaded by B on the computer according to the situation, and B's BT will get the N part downloaded by A on the computer according to the situation, which not only reduces the load on the server side, but also accelerates the download speed of users (A and B). Efficiency has also improved, and restrictions between regions have also decreased. "For example, if C wants to connect to the server to download, it may be only a few K, but if it goes to A and B's computers, it will be much faster ... So the more people use it, the more people download it, and the faster everyone will be. This is the advantage of BT. And when you download, you are uploading (someone else took a part of that file from your computer), so you are also contributing while enjoying the download provided by others.
3. Search engine-the design of adaptive information retrieval system based on P2P.
The network topology of the adaptive information retrieval system based on p2p proposed in this paper is shown in figure 1. The system consists of several autonomous nodes, which form an information retrieval network according to the network architecture, and each node is peer-to-peer. Each node consists of a client agent and a server agent. Users submit questions through the client agent. For each problem, the client agent can use any combination of meta-search, crawler and forwarding to the server agent according to the specific situation. For the results returned by these three methods, the client agent will present them to the user after merging and filtering. When users browse the results, they submit relevant feedback to the client agent by marking the documents as interested or uninterested. Using these feedbacks, the client agent can build a user model, which can be used to filter the results in the future, and also be used to modify the user's original questions for further retrieval processing in the future. At the same time, the server agent is responsible for the communication between nodes. It can cluster users on the basis of receiving user models and related documents, and realize collaborative recommendation and forwarding retrieval requests among users with the same or similar interests on the basis of clustering. The internal structure design of a single node is shown in Figure 2.
4. Collaborative work-the influence of ——p2p technology on e-learning application mode.
Knowledge exchange and learning based on P2P;
P2P is a technology, but it is also an idea that has the potential to change the status quo of the whole Internet. It connects people directly, and people can interact directly through the Internet, making network communication easier and resources more direct. Therefore, it has great prospects in strengthening network interpersonal communication, file exchange and distributed computing. With the rise of P2P technology, knowledge exchange based on P2P ideas has also begun to appear on the network. For example, the scheme provided by LearningIDEAS Company, which can instantly capture the knowledge exchange between individuals, includes a unique matching and forwarding system, so that external knowledge can be transmitted in real time with information exchange. The technology of LearningIDEAS is very similar to the routing system of enterprise call center, which allows routing and matching based on knowledge and skills, and can connect one user with another related user when actual needs and specific problems occur. Compared with the traditional e-Learning system, the biggest difference of the knowledge exchange scheme based on P2P is that it can provide a channel for knowledge sharing between learners and others without creating a special learning environment or formally arranging teaching activities.
At present, mainstream e-learning systems such as Ellumniate, Centra and WebEx also provide some synchronous learning and collaboration solutions (such as virtual "online meeting rooms"). Although they can allow learners to communicate informally and directly, such learning activities generally need to be clearly planned and arranged in terms of theme, time and communication personnel. The knowledge exchange scheme based on P2P is different. When a user or student encounters some difficulties, he expresses his problems in the LearningIDEAS system, and the system can immediately help him to transfer to colleagues or student users who have experience in solving such problems. Just like asking questions and communicating with people around you at will, this virtual instant communication method can solve the real problems encountered by users more quickly and eliminate the time and space obstacles in learning through the formal teaching system.
The real value of informal knowledge exchange scheme based on P2P technology lies in that it enables learning and communication to be carried out on the Internet at any time and can be integrated into the actual work and life process. This random, free and timely knowledge exchange scheme not only makes learning interaction happen around every network user, but also makes the learning process of informal knowledge exchange recorded and archived. When people join the P2P network, all users have equal opportunities. They can easily exchange ideas freely on the network, exchange and learn at any time, and then get the knowledge and information they need from each other. P2P has got rid of the fetters of intermediary services, which directly reconnects people through the network, making the exchange of knowledge between people faster and more convenient, thus improving people's efficiency in solving learning problems and handling social affairs.
Fourthly, the shortcomings of p2p technology and the current solutions.
Management and security are the biggest problems that p2p faces at present.
In the p2p technology architecture, the meaning of the central node is greatly weakened or even completely dissolved. The characteristics of decentralization will be more fully reflected, and the flattening characteristics of network communication structure will be further highlighted. This communication structure makes the management and control of network information communication more complicated and difficult. From the management point of view, the main challenges of p2p technology are reflected in two aspects: the control of bad content dissemination is more complicated; Copyright management is more difficult.
In foreign countries, the problems brought by p2p in copyright management have attracted more attention. It is reported that the Intellectual Property Office of the US Congress has drafted a new version of the bill, trying to ban the application of such p2p software. As early as June 5438+ 10, 2003, Britain passed legislation to implement the controversial European copyright law. This legislation makes it clear in theory that using similar p2p services may constitute a crime.
The current solution: using JXTA technology (parallel technology).
JXTA technology provides the core technology for constructing P2P network applications, aiming at establishing a general development platform for P2P applications. JX2TA technology mainly includes a protocol set independent of programming language system platform and network platform, which explains the most basic requirements of P2P applications. It can be said that JXTA is a P2P stack under the P2P network service or application on the operating system or virtual machine, which provides the core functions required by P2P applications. However, some people are critical of this. For example, Fang Xingdong thinks that p2p communication should not be restricted by intellectual property rights if it is between individuals and there is no commercial activity.
Of course, technology can't solve all the problems, and relevant legal means need to be strengthened. However, the formulation of laws should focus on the future rather than the present, focusing on the overall interests of society rather than personal interests.
5. Prospects
From the development track of p2p technology, it is consistent with the development of Internet technology, that is, from technology-oriented to market-oriented, from exclusive users to ordinary users, which means that the influence of these technologies will shift from purely technical level to economic, cultural and social level.
Because p2p technology can facilitate information exchange and enjoyment between people, it can also provide possibilities for information exchange and cooperation between media. P2p technology may also become a new platform for communication and cooperation between media, and may also accelerate the evolution of media forms. For media organizations, what they can feel now seems to be more of a potential threat, because their privileged position in traditional media and online media will be challenged. However, from another perspective, if media organizations regard themselves as producers of general information products, they may find new hope from 2 technologies.
As a technology with more and more universal application value, the influence of p2p on the future network communication characteristics is beginning and will continue, although it is difficult to make a comprehensive description at present. This is like the popularization of technology, which greatly enhances the attribute of the network as a mass media.
References:
1. The Future of P2P Technology and Network Communication Peng Lan Vol.7No.1Journal of Nanjing University of Posts and Telecommunications
2. Design of adaptive information retrieval system based on P2P Jiang Qi.
3. The influence of technology concept on the application mode of online learning in Li Peng.
4. Talking about the next generation Internet technology-grid technology.
5. Information technology A brand-new P2P network solution technology Zheng Xuanxia
6. Research and Application of 6.P2P Technology Zhou Yonglin, Binxing, Chen Shufang
7.7 Application and research status. P2P Technology Zhao Heng Chen Jie