Eddie is a high availability clustering tool. It is an open source, 100% software solution written primarily in the functional programming language Erlang (http://www.erlang.org/) and is available for Solaris, Linux and *BSD.
Eddie provides advanced automatic traffic management and configuration of geographically distributed server sites, consisting of one or more Local Area Networks.
At each site, certain servers are designated as Front End Servers. These servers are responsible for controlling and distributing incoming traffic across designated Back End Servers, and tracking the availability of Back End Web Servers within the site. Back End Servers may support a range of Web servers, including Apache.
Currently, Eddie consists of two main software packages:
Enhanced DNS
For server sites distributed over a city, a country, or even the world, Eddie's Enhanced DNS allows the entire distributed web server capacity to be usable. The individual sites may have different numbers of servers, different vintages of computer, even different operating systems.
The load information passed between servers at a site is processed locally and summary information passed to each Eddie Enhanced DNS server, across the Internet if necessary.
The Eddie Enhanced Domain Name Service package dynamically balances client domain name resolution requests across all sites in the distributed server, and more specifically, across each Front End within each site. The balancing is performed to keep each site working at approximately the same fraction of its overall capacity, rather than equalising the number of requests sent to each site, as occurs with Round Robin based schemes. This ensures maximum efficiency of Front End Server resources within each site.
Intelligent HTTP Gateway
Within a single site, Eddie's Intelligent HTTP Gateway supports superior functionality and performance. Load information passed to Front End Servers running the Intelligent HTTP Gateway package enables,
- Dynamic load balancing to be employed, maximising the capacity of the site.
- Automatic discovery of failed servers and subsequent re-direction of traffic, thereby improving reliability.
- Site scalability through simple addition of extra servers as needed.
- Advanced admission controls to be employed to improve user Quality of Service.
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