Coral Content Distribution Network
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| Developer(s) | Michael Freedman |
|---|---|
| Initial release | 2004 |
| Development status | Inactive |
| Operating system | Cross-platform (web-based application) |
| Type | P2P Web cache |
| Website | www.coralcdn.org |
The Coral Content Distribution Network, sometimes called Coral Cache or Coral, was a free peer-to-peer content distribution network that ran from 2004 until 2015. It was designed and operated by Michael Freedman. Coral used the bandwidth of a worldwide network of web proxies and name servers to mirror World Wide Web content, often to avoid the Slashdot Effect or to reduce the load on web servers.
Coral avoided high loads on individual nodes through an indexing abstraction called a distributed sloppy hash table (DSHT); DSHTs create self-organizing clusters of nodes which fetch information from each other to avoid communicating with more distant or heavily-loaded servers.
The sloppy hash table refers to the fact that Coral was made up of concentric rings of distributed hash tables (DHTs), each ring representing a wider and wider geographic range (or rather, ping range). The DHTs are composed of nodes all within some latency of each other (for example, a ring of nodes within 20 milliseconds of each other). It avoids hot spots (the 'sloppy' part) by only continuing to query progressively larger sized rings if they are not overburdened. In other words, if the two top-most rings are experiencing too much traffic, a node will just ping closer ones: when a node that is overloaded is reached, upward progression stops. This minimises the occurrence of hot spots, with the disadvantage that knowledge of the system as a whole is reduced.
Coral users could access content through the Coral Cache by adding .nyud.net to the hostname in the site's URL, resulting in what is known as a 'coralized link'. So, for example,
becomes
Any additional address component after the hostname remains after .nyud.net; hence
...
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