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In this article:
- What is File Sharing
- History of File Sharing
- Network Architectures for File Sharing
- Classification of file sharing networks
What is File Sharing
Making a file or a set of files available for download by other people via the Internet or other networks is called file sharing. Today, the common method of file sharing is a peer-to-peer or P2P network where the files to be shared are stored on personal computers of the users, instead of placing them on a central server. People can then connect to the computers and download the file they want and may or may not give something in return. In the real world, however, most files being shared are actually copies of copyrighted material including e-books, music files as well as movie and music videos.
History of File Sharing
Though the practice of file sharing is very old and has existed even before email came into being, today, it usually means sharing files over a P2P network. File Transfer Protocol or FTP is another common way of sharing files since the very beginning and continues to be used today as well.
File sharing overwhelmed the world when the MP3 format became popular in the 1990s. At that time, people uploaded mp3 files to a hosting website (almost always a free one like Geocities) and allowed them to be downloaded from there. This, however, came to the notice of the web hosting companies and was immediately terminated. There was a war between the hosting companies and the people who uploaded such files to counter each other. The war came to a standstill when the P2P file sharing networks came into existence and it became even easier to share any kind of file anywhere in the world. The first of these networks was Napster which started off in 1999. A mp3-only file sharing network, it shot up to overnight popularity reaching its peak in 2001, the year it was finally closed down due to legal problems with the music industry.
Gnutella is another decentralized P2P network which is open source and allows the sharing of any type of file. BitTorrent has also played its own part in the file sharing scenario and has seen some popularity.
Today, however, a variety of computer programs provide the same functionality, an example being that of LimeWire.
Types of File Sharing Networks
File sharing networks that follow the Peer-to-peer method are sometimes classified as belonging to a particular generation. However, this classification is not definitive and is rather a result of general agreement rather than being an official standard. The networks are classified as under:
- First generation
The first generation of peer-to-peer networks was comprised by networks such as Napster. This was a nascent stage for file sharing networks of today and a centralized approach was followed. The server (such as Napster) would keep a file list which indexed all the people connected to the server and the files that they had. When a person wanted to download a particular file, he or she could perform a search for it. The server would then retrieve the names of the nodes that had the file and the person could chose to download from them, the download being assisted by the central server. This was the basic cause of the legal problem that Napster went into since the US court held it responsible for copyright infringement since it controlled the centralized list.
- Second generation
These came after Napster had died down, specifically the one made by Justin Frankel from Nullsoft (and named Gnutella). These types of networks let some ‘weak’ nodes to branch-off from a stronger node, making it simpler to handle the size of the network as it continued to grow. This approach is followed today as well.
- Third generation
While third generation file sharing networks are nearly the same as their predecessors, they have a unique feature of anonymity. It is not possible to pinpoint a user who downloaded a particular file over the network. They also stop traffic sniffing by encrypting the data that travels over the network. However, these networks are still very slow owing to these features and hence are not yet popular.
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