Are you tired of clicking on some link from a web portal, only to find that the website is temporarily off-line because thousands or millions of other users are also trying to access it? Does your network have a really low-bandwidth connection, such that everyone, even accessing the same web pages, suffers from slow downloads? Have you ever run a website, only to find that suddenly you get hit with a spike of thousands of requests, overloading your server and possibly causing high monthly bills? If so, CoralCDN might be your free solution for these problems!
What is CoralCDN?
CoralCDN is a free and open content distribution network based around peer-to-peer technologies, comprised of a world-wide network of web proxies and nameservers. It allows a user to run a web site that offers high performance and meets huge demand, all for the price of a $50/month cable modem.
Publishing through CoralCDN is as simple as appending a short string to the hostname of objects' URLs; a peer-to-peer DNS layer transparently redirects browsers to participating caching proxies, which in turn cooperate to minimize load on the source web server. CoralCDN proxies automatically replicate content as a side effect of users accessing it, improving its availability. Using modern peer-to-peer indexing techniques, CoralCDN will efficiently find a cached object if it exists anywhere in the network, requiring that it use the origin server only to initially fetch the object once.
One of CoralCDN's key goals is to avoid ever creating hot spots in its infrastructure. It achieves this through a novel indexing abstraction we introduce called a distributed sloppy hash table (DSHT), and it creates self-organizing clusters of nodes that fetch information from each other to avoid communicating with more distant or heavily-loaded servers.
CoralCDN has been continuously operated since March 2004, running on 300-400 servers on the PlanetLab testbed, spread worldwide. As of 2011, it receives 25-50 million requests per day from a few million unique clients.(What's with the Google ads? Our Illuminati measurement project sought to understand how IP addresses and public information characterize Web clients. One related question is how such information plays a role in pay-per-click advertising, so we decided to run some ourselves to better understand how such systems work.)