Binary newsgroups

While newsgroups were not created with the intention of distributing binary files, they have proven to be quite effective for this. Because of the way they work, a file uploaded once will be spread and can then be downloaded by an unlimited number of users. More useful is that every user is drawing on the bandwidth of his or her own news server. This means that unlike P2P technology, the user's download speed is under his or her own control, as opposed to under the willingness of other people to share files. In fact, this is another benefit of newsgroups: it is usually not expected that users share. If every user makes uploads then the servers would be flooded; thus it is acceptable and often encouraged for users to just leech.

There were originally a number of obstacles to the transmission of binary files over Usenet. First, Usenet was designed with the transmission of text in mind. Consequently, for a long period of time, it was impossible to send binary data as it was. So, a workaround, Uuencode (and later on Base64 and yEnc), was developed which mapped the binary data from the files to be transmitted (e.g. sound or video files) to text characters which would survive transmission over Usenet. At the receiver's end, the data needed to be decoded by the user's news client. Additionally, there was a limit on the size of individual posts such that large files could not be sent as single posts. To get around this, Newsreaders were developed which were able to split long files into several posts. Intelligent newsreaders at the other end could then automatically group such split files into single files, allowing the user to easily retrieve the file. These advances have meant that Usenet is used to send and receive many terabytes of files per day.

There are two main issues that pose problems for transmitting binary files over newsgroups. The first is completion rates and the other is retention rates. The business of premium news servers is generated primarily on their ability to offer superior completion and retention rates, as well as their ability to offer very fast connections to users. Completion rates are significant when users wish to download large files that are split into pieces; if any one piece is missing, it is impossible to successfully download and reassemble the desired file. To work around the problem, a redundancy scheme known as PAR is commonly used.

A number of websites exist for the purpose of keeping an index of the files posted to binary newsgroups.

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