What is P2P software?

P2P is the abbreviation of peer-to-peer. Peer means "peer", "colleague" and "partner" in English. In this way, P2P can also be understood as "partner-to-partner" or peer-to-peer networking. At present, people think that it has great prospects in strengthening people's communication, file exchange and distributed computing on the network.

Simply put, P2P directly connects people and allows them to interact directly through the Internet. P2P makes communication on the Internet easier, more direct and more interactive, and really eliminates middlemen. P2P means that people can directly connect to other users' computers to exchange files, instead of connecting to the server to browse and download as in the past. Another important feature of P2P is to change the current state that the Internet is centered on large websites, return to "decentralization" and return power to users. P2P seems very new, but just as B2C and B2B transplant common things in the real world to the Internet, P2P is nothing new. In real life, we communicate face to face or by telephone every day according to the P2P model.

Even from the network point of view, P2P is not a new concept. P2P is the foundation of the whole Internet architecture. TCP/IP, the most basic protocol of the Internet, has no concepts of client and server, and all devices are equal terminals of communication. Ten years ago, all systems on the Internet had the functions of both server and client. Of course, the later developed software based on TCP/IP did adopt the client/server structure: browser and Web server, mail client and mail server. However, for the server, it is still point-to-point networking. Take e-mail as an example. There is not a huge and unique mail server on the Internet to handle all the mail, but peer-to-peer mail servers cooperate with each other to send the mail to the corresponding servers. In addition, e-mail between users has always been a point-to-point communication channel. Of course, but in the past five years, the development of the Internet is far from P2P at least on the surface, and most nodes on the Internet can't communicate directly with other nodes. Napster is the awakening of peer-to-peer network hidden behind the Internet. It is also common to share Napster files in the LAN * * * sharing directory. However, the success of Napster makes people realize the possibility of extending this "peer-to-peer networking" to the whole Internet. Of course, in the eyes of many people, Napster is not pure P2P, and it still needs a central coordination mechanism.

In fact, many existing services on the network can be classified as P2P. Instant messaging systems such as ICQ, AOL Instant Messenger, Yahoo Pager, Microsoft's MSN Messenger and China's OICQ are the most popular P2P applications. They allow users to communicate with each other and exchange information and files. The information exchange between users is not direct and needs to be coordinated through a central server. However, these systems do not have functions such as searching, which is very important for enjoying a large amount of information. The lack of this function may be one of the reasons why instant messaging has existed for a long time, but it has not had such a big impact as Napster.

Another auction website that can be classified as P2P, such as Yi Bei, does people use C2C when summarizing Yi Bei's model? Is it similar to P2P? EBay is a community that connects people and trades goods, and users can easily search for goods sold by other users. EBay provides some services to make the transaction go smoothly, but the transaction is directly between users. If the concept of "transaction" is generalized, C2C is a special case of P2P, and people exchange goods.

However, if we study it carefully, Napster and instant messaging give users the ability to communicate directly, while Yi Bei enables users to trade directly, but at the same time, they destroy the idea of peer-to-peer networking that has existed on the server side since the emergence of the Internet, because they all need a central server to coordinate, instead of many servers distributed in different parts of the world. It is precisely because Gnutella and Freenet keep claiming that they have created a "pure" P2P service without a central server at all.

(2) The ideological source of P2P is to return to the essence of the Internet.

If we look back, we will find that at the beginning of WWW, P2P was one of the essential features of the Internet. People build their own web pages and link to each other. People surf the Internet along the links. At that time, the web was the real "web". But when Yahoo! After establishing search engines and portals with Lycos, the way people surf the Internet has been changed, and people go to one place to get all the information. I remember that Sina once said that they were "target sites" for a while, but ask another question. Do you still have the concept of "net" in your mind when you watch Sina news one by one? The biggest problem is that these websites control the flow of information, are full of outdated information and hinder real communication, or for many people, there are too many advertisements. P2P is to give control back to users. People can enjoy files, directories and even the whole hard disk through P2P. This energy is very exciting. What they have worked so hard to store on their hard drives must be the most valuable. Everyone enjoys what he thinks is most valuable, which will greatly enhance the value of information on the Internet. Are you as excited as when WWW first appeared? A little bit.

Because every peer represents the following people, the network community based on self-organization is also emerging. Different from the way portal websites build communities from top to bottom, people will spontaneously form communities.

When people join the P2P network, everyone has equal opportunities, and everyone has the opportunity to easily create "content" on the network. Of course, only a few people actually create or provide content on the Internet. According to statistics, only 2% of Gnutella users provide content to other users, and even users who post articles on active newsgroups account for only 7% of all users. However, for the first time, P2P gives all people who surf the Internet equal opportunities.

The following attempts to reveal the influence of P2P in three sentences:

Peer-to-peer network is the end of read-only network.

Peer-to-peer allows you to participate in the Internet again.

As mentioned above, P2P is not a new concept. In some ways, it is even the initial creation of the whole mutual.

The most basic idea of network. We might as well take some time to do a little review.

The development of the Internet is no different from many advanced technologies in modern times, that is, it was first formed in the military field and then transferred to the civilian field. Internet originated from a novel strategic idea: what should be done to prevent the enemy's destructive weapons from hitting military command and control centers all over the country? On the one hand, the traditional methods try not to let the enemy know the exact location of the center, on the other hand, they improve the ability of the center to resist attacks. However, in today's nuclear age, the other side has a nuclear bomb, which can even blow up a planet. Once attacked, the impregnable defense measures will definitely go up in smoke. As long as there is a secret, there is always a way to find it out, so relying on the location of the security center is not a long-term solution. In this case, the US military personnel give full play to the reverse thinking and think that since it is impossible to effectively protect the center from attacks for a long time, it is better not to set up a center at all! Let every base, even every computer, operate independently, which means there are countless centers. Unless the enemy really blows up the planet, one of the bases or computers is damaged, which will not affect the continued operation of other bases or computers. It is this idea of "decentralization" that has become the most basic concept of the Internet. However, after many technologies appear, they often do not develop completely according to the original design. The server/client architecture has gradually become the mainstream of the Internet, and browsing has become the most important way of life for people on the Internet. Ordinary users of the Internet seem to be slowly degenerating, passively browsing the content created by big websites like TV viewers. People's main activities on the Internet are visiting such portals, reading news, participating in discussion groups and chatting. But this makes one of the characteristics of the designed Internet disappear-what happens if Yahoo interrupts its service for some reason? This assumption is not easy to see, but the confusion caused by hackers attacking major websites at the beginning of the year seems to give us some Lenovo clues.

As mentioned above, Napster and instant messaging still need a central server, so a sentence on Gnutella's website may express the concept of "decentralization" contained in their "pure" P2P: Gnutella was designed to survive in nuclear war. According to its website, the attack on users in new york will only affect some users in this area at most, while users in other places can still use Gnutella normally. Isn't this the original ideal of the Internet?

The revolution brought by Napster

Napster was developed by Shawn Fanning, who was only 18 years old last year. It provides a service that allows music lovers to exchange MP3 files. It is different from MP3.com, which provided free music download before, because there are no songs on Napster server. Napster provides a new software for music lovers, which can * * * enjoy the song files on their hard disks, search the song files enjoyed by other users, and download the songs on the hard disks of other users who also use Napster service. Napster attracted 50 million users in a short time, and was finally put in the dock by five major record companies for copyright infringement, which became the focus of the world.

Perhaps there has never been an industry like the recording industry, and its survival will be threatened so deeply by a small software. There has been a lot of discussion about copyright issues caused by Napster, but it is worthwhile to spend more time discussing it, because this case determines the future of this branch of P2P file sharing and how to deal with copyright issues on the Internet in the future.

BMG, one of the plaintiffs, reached a settlement agreement with Napster. According to public opinion, this shows that the recording industry realizes that digital music distribution will be an irresistible trend, and the elimination of Napster will not prevent other service providers imitating Napster from appearing. So it is better to cooperate with Napster and change it into a channel for online music sales. Now the recording industry may not be faced with how to crush it like an egg, but to cooperate with it and turn Napster's 50 million users into their own customers. That is to turn Napster mode into "legal Napster" mode. The dilemma of the recording industry is how to prevent Napster imitators from continuing to provide songs for free.

On February 12, 2000, three judges of the Court of Appeals for the Ninth Circuit in San Francisco, USA, ruled on the copyright dispute of the music website Napster, arguing that it infringed the copyright of major record companies. However, the three judges did not immediately shut down the website at the request of the record company, but sent the preliminary judgment back to the local lower court. The judge said that the content of the ruling was too complicated and needed further clarification. However, the complicated legal process and the 58-page judgment reflect the lack of Internet-related copyright law and judicial practice.

However, no matter what the outcome of the Napster case is, it cannot change the influence of the technology and ideas behind Napster on the Internet. The devil has drilled the magic bottle, and the magic bottle has been broken. For the record industry, at least the way they sell records has completely changed. The next one may be the Hollywood film industry. Compression technology and broadband network will make it easy for people to transmit the whole movie on the network.

In fact, many companies have tried to launch the "legal Napster" model on the legal network, such as lightshare.com and Flycode.com, one of the founders of Napster. If P2P can charge users, it is really attractive to record companies. For mp3 music download with centralized website, every time users download from the website, the website must communicate with telecom, but the use of P2P makes this part of the cost disappear. In this way, record makers can get more profits, and users should also get cheaper music.

In a sense, software seems to have predicted the possible impact of large-scale piracy and file sharing, which is mainly due to the "brainstorming" brought by open source software to the software industry. In Asia and Eastern Europe, the software industry has lost the fight against piracy. This is also a "software registration model" promoted by Microsoft, which sells software as a monthly payment service instead of selling hard copies that are easy to copy and pirate as in the past.

Of course, there are still many questions about the so-called "legalized Napster" model. This file sharing function of P2P doesn't seem to bring any added value, although the process may be interesting. On the other hand, this technology may be used to promote people to re-participate in the Internet and create their own content, which may be the value. All community websites have a "dream" for users to interact and produce content, but this dream has never really come true because of the most fundamental problem of top-down communities. P2P may be able to change this.

The miracle created by Napster also reveals that ordinary people also have the ability to change the whole world in the Internet age. When sean fanning developed Napster on the campus of Northeastern University, he just wanted to share mp3 song files with his friends in Virginia. Now this little software has changed the whole world.

(4) What has 4)p2p changed? The content moves to the "edge"

After reviewing Napster's problems and dilemmas, let's look at more wonderful things about P2P, eliminate all kinds of misunderstandings around this new word, and see where the opportunities of P2P are mainly.

One of the changes brought by P2P is to change the position of "content", which is moving from "center" to "edge", that is, the content will mainly exist on all users' personal computers, not on several major servers.

The success of Napster makes us have to question two long-standing assertions: "Application Service Provider (ASP) is the future trend" and "Personal computer is dead". A basic assumption of ASP is that the cost of purchasing and maintaining a high-performance server is too high for most customers, but P2P makes everyone's desktop computer a "server". Users used to use desktop computers to prepare data before uploading it to the server, but P2P will no longer need this process. The assertion that "personal computers are dead" means that personal computers will be mainly used for browsing the Internet and word processing, so the simplest thin client can meet the demand. P2P makes personal computers "centralized" again. Peer-to-peer (P2P) rejuvenates the personal computer, which is no longer a passive client, but a device with both server and client characteristics. The personal computer will once again become the center of the Internet.

The storage mode of the Internet will change from the current "content in the center" mode to the "content in the edge" mode. From this perspective, P2P has brought several changes:

First of all, customers no longer need to upload files to the server, only need to use P2P to provide * * * information;

Secondly, the personal computer running P2P does not need a fixed IP address and a permanent Internet connection, which makes those dial-up Internet users enjoy the changes brought by P2P, accounting for a large proportion of all users.

Finally, P2P completely changed the client/server mode that used to control the Internet, and eliminated the difference between client and server.

There is a lot of discussion about the legal problems encountered by Napster, but from another perspective, piracy often shows that there are a lot of unmet needs. Napster's amazing success (in this case, attracting a large number of users instead of making profits) is a rare proof of the feasibility of P2P concept, revealing the potential of P2P to change the Internet. The desktop broadband network has gradually become a reality, and personal computers are becoming more and more powerful, which is enough to be competent as a "server", which also ensures that P2P can exert its energy from another aspect.

Replacing the central server with a personal computer as the main storage place of content will have a far-reaching impact on several main development directions of the Internet: this may change the situation of the "war" between Windows and Linux for several years. When "desktop" and server gradually merge, Microsoft may vigorously promote its Web service based on Windows2000 and "content on the edge" (content on the desktop) mode, which may destroy the foundation of Linux's existence in the server market.

One of the reasons why companies provide free personal homepage services exists is that the current Internet makes it difficult for ordinary users to have their own servers to place their own content. It can be predicted that services like Napster will appear for people to publish home pages and content on personal computers.

At present, WAP and other mobile service protocols mainly focus on letting people use central business services such as news and stock information. But more often, the information people need most is the information on personal computers, and P2P makes it possible. People can access their personal computers through wireless P2P, which is a "wireless version" of personal P2P promoted by some companies.

Of course, this does not mean that personal computers using P2P can replace servers, and those secure backups and data that need constant updating by experts will still exist in the central server. We can look at the changes brought by P2P in this way. The "content-centered" model is well adapted to the initial situation of the Internet. The performance of personal computers is so poor that they need special servers, and the bandwidth is so narrow that personal computers have to degenerate into passive browsing. Broadband internet, more stable and higher-performance personal computers give us reason to predict that the next five years will be dominated by the "marginal content" model.

(5) Re-interpret P2P

Every epoch-making innovation may be misunderstood when it appears. P2P is no exception this time. Napster makes people pay attention to P2P, but it also makes many people think that P2P is the exchange of songs and files, and even thinks that P2P is necessarily related to piracy. It can be said that people's understanding of P2P is misleading and incomplete.

At the beginning of its appearance, free software also faced the dilemma of being misread. At the beginning, people understood freedom as free, so that free software was unreliable and the free software movement was a radical "counterculture". In fact, free should mean to explore ideas freely, express them in software and enjoy the software. This is natural for advocates of free software, but someone needs to tell business, media and the public that free software is economically and logically feasible. At that time, the famous publisher O'reilly organized a free software summit, redefined free software and renamed it open source software. This redefinition makes people begin to clear the dark clouds of misunderstanding and understand the essence of free. Open source liberates people from flawed software, lock-in effect and traditional software distribution channels. Freedom means that cooperation will cross the company's boundaries, enjoy basic development and make people focus on high value-added services. In August this year, O'Reilly organized another summit to help people understand the potential of P2P and eliminate the negative impact of P2P as a pirated technology caused by Napster and Gnutella. In addition, he believes that the current state of P2P is similar to "the blind touch the elephant", and everyone who is the leader of P2P technology has seen some characteristics of this "giant elephant". If they can have the opportunity to exchange ideas, P2P will develop faster. This P2P summit has three main purposes: to define P2P, what we should learn from it and why; Describe the opportunities of P2P and what problems P2P can solve; Form a P2P information for the public and eliminate those negative effects.

Participants in P2P summit include developers who provide file exchange services, such as Napster, Gnutella and Freenet, and developers of companies and organizations that try to take advantage of P2P distributed computing capabilities, such as Popular Power, SETI@home and Distributed. The latter three companies hope to use P2P technology to centralize the idle CPU time, memory space and hard disk space of computers connected to the network, rather than "supercomputers". Other ongoing P2P applications include: IBM, Microsoft and Ariba are also cooperating in a project called UDDI to standardize B2B e-commerce; Eazel is building the next generation Linux desktop; Jabber developed an open instant messaging standard based on XML, and Jabber is considered as the standard of P2P data exchange in the future. Groove created by the developer of Lotus Notes tries to "help people communicate in a new way"; Intel is also promoting its P2P technology to help use the computing power of the chip more effectively.

Making such a list is a bit boring, especially for readers who are not interested in specific details, but it is necessary. Because these descriptions can give us a more comprehensive understanding.

(6) Unknown P2P

Napster is device-related, and users connect to the P2P network created by Napster in order to obtain Mp3 song files. But it is completely different for P2P applications such as instant messaging. The purpose of others' connection is to communicate with another colleague, whether he uses a computer, PDA or mobile phone. P2P provides real-time network communication capability independent of devices.

This ability to connect users in real time is the most exciting feature of P2P. In fact, we can realize this fact from the popularity of AOL's AIM and domestic Oicq.

Being able to find and contact people in need in real time is the basic requirement of commercial application. The telephone can do this, but the most commonly used email on the Internet can't. Therefore, instant messaging is not only an interesting service, but also the next most basic Internet business tool. Now, instant messaging seems likely to become a platform for business applications such as customer service and supply chain management. Jabber developed an open source instant messaging service based on XML and Java, and he seems to have created such a platform. Jabber's developers seem to deliberately put all the exciting things on the Internet together: P2P, Java, XML and open source. Does it have this potential? We'd better wait and see, but Jabber's model is at least much clearer than Napster's.

Negroponte once famously said in his "Digital Survival" that "there will be more things on the Internet than people". P2P will make it possible for these "things" to communicate directly. Every device on the network is "active", not as in the past, some are very active and some are very passive. Sometimes, devices that communicate directly may all belong to one user. For example, data synchronization between PDA and desktop computer is the best example. If the user's PDA has some data and contents that are not available on the desktop computer, the desktop computer should also be able to request these information from the PDA, which should be the same as searching and downloading other users' mp3 songs through Napster.

The most important point is that it is not the number of nodes on the network that determines whether the network is strong and valuable, but how these nodes participate in the network. How to make hundreds of millions of people and more devices actively participate in the network? P2P is the beginning of a series of architectures, technologies and strategies, which make this ideal of the Internet come true. What people see and predict now is only a small corner exposed by the iceberg, and more is still underwater.

7) 7)P in P2P is human!

Dave Wenner asserts that P in P2P is human! This is probably one of the most profound interpretations I have ever seen about P2P.

In fact, the reality of our life is a P2P environment where people can communicate directly with each other. Information technology has brought us to cyberspace, where we still hope to communicate in the original P2P way. Although the Internet essentially supports peer-to-peer communication, the development of the network has added many obstacles to peer-to-peer communication.

As many technical experts have pointed out, dynamic IP addresses, firewalls and proxy servers make peer-to-peer connection technically difficult. What's more, the current network-oriented model has developed into a server/client model, and people can only passively accept those big companies such as Yahoo! ABCnews.com, wait, it's hard to communicate. (Of course, in real life, such as space, social class, etc. It also restricts people's peer-to-peer communication. But if the network can let us see the possibility of peer-to-peer communication, why not pursue it? )

Analogously, the emergence of the Internet has the same significance as the invention of the telephone, but the main feature of the Internet at the beginning is non-real-time, more similar to fax, rather than providing real-time communication like the telephone. Now P2P instant messaging may make real-time communication on the Internet as common and indispensable as web pages and emails.

For all P2P applications, the first thing to do is to restore the point-to-point networking capability that the Internet once lost. This is Napster's biggest conceptual flaw. E-mail has the characteristics of P2P communication, but it lacks the ability of real-time communication. It's similar to fax, but we still need "telephone". )

From the perspective of "people", the key point of P2P development is not the P2P network architecture, but that P2P connects people on the network, and people can deal with those problems that need communication on the network, which is a faster medium. That's all that matters. Although some people still doubt the effectiveness of the Internet as a retail business and B2B media today, the Internet has fundamentally changed our way of communication without any discussion. It is meaningless to talk too much about "pure" P2P that completely eliminates control. Centralization or decentralization are just tools. They are all for creating tools to enable people to communicate more effectively.

So far, only a small part of human experience in real life has been applied to the Internet, such as news, B2C and B2B. Nowadays, P2P, which people use most often, has been transplanted to cyberspace. P2P may change some products and services that we are already familiar with and used to, and create more.

What will happen? The best way to predict the future is to create.

2. What can 2.p2p do?

P2P leads the transformation of network computing mode from centralized to distributed, that is to say, the core of network application spreads from central server to terminal devices on the edge of the network: server to server, server to PC, PC to PC, PC to WAP mobile phone ... All devices on network nodes can establish P2P sessions. This enables people to enjoy by going up one flight of stairs on the Internet and participate in the Internet in a more active and profound way. As Doug. Fan Houweilin, the father of I2 (the second generation Internet), said in a trip to China a few months ago: "The next generation of Internet users will really participate in the network, and everyone can make their own contribution to the expansion of network resources and functions."

P2P brings infinite reverie to the distribution and enjoyment of the Internet. Some people think that at least 100 applications can be developed, but from the current application point of view, the power of P2P is mainly reflected in the advantages of enjoying and searching widely. In this respect, four kinds of applications on the network are mainly triggered or solved well: peer-to-peer computing, collaborative work, search engine and file exchange.

(1) peer-to-peer computing

It has always been a dream of scientists to complete the functions of supercomputers through multiple computers. Peer-to-peer computing using P2P technology is to connect the computing power that many computers in the network have not used for the time being and use the accumulated power to perform the tasks of supercomputers. Any industry that needs a lot of data processing can benefit from peer-to-peer computing, such as weather forecast, animation, genome research and so on. With peer-to-peer computing, there is no need for expensive supercomputers. Now many companies in Silicon Valley are investing in the development of P2P computing, such as Popular Power, Centrata, United Devices, Entropia and so on. And obtained huge venture capital. Intel also uses peer-to-peer computing technology to design its CPU, which saves a lot of money. At the same time, the development of peer-to-peer computing is based on the effective use of PC resources, which is naturally highly praised by Intel. Essentially, peer-to-peer computing is the enjoyment of CPU resources on the network.

(2) cooperative work

With the increasing decentralization of enterprises, it is becoming more and more important to provide simple and convenient news and collaboration tools for employees and customers. The emergence of network makes cooperation possible. However, the traditional WEB implementation has brought a great burden to the server, resulting in expensive costs. With the emergence of P2P technology, any two PCs on the Internet can establish real-time contact, so a safe virtual space is established, where people can carry out various activities, which can be carried out simultaneously or interactively. Peer-to-peer technology can help enterprises to establish secure online working contacts with key customers and partners, so collaborative work based on P2P technology has also received great attention. Aoqi, the founder of Lotous Company, has obtained 60 million US dollars of venture capital to develop its collaborative work product Groove.

(3) Search engines

Another advantage of P2P technology is to develop powerful search tools. Peer-to-peer technology enables users to search documents in depth, which is not limited by the format of information documents and host equipment, and can reach an unparalleled depth (theoretically, it will include all open information resources on the network) of traditional directory search engines (which can only search 20%-30% of network resources). Take the search conducted by Gnutella, another pioneer of P2P technology development, as an example: Gnutella software on one PC can send the user's search request to another 10 PC on the network at the same time. If the search request is not satisfied, each of the 65,438+00 PCs will forward the search request to another 65,438+00 PCs, so that the search range will be within a few seconds.