User:Alcot/WorldDirector

WorldDirector is a Content Delivery Network technology believed to be the first of its kind.

History
WorldDirector was conceived in late 1994 at NEXUS International Broadcasting Association non profit R&D labs in Milan, Italy, in order to overcome network bottlenecks of Internet users who had difficulties in downloading content or streaming audio from remote locations at the edge of the Internet. WorldDirector was originally deployed in late 1994 for streaming audio, ftp archives and web pages belonging to the NEXUS association's members, to the extent of providing easier access to the information by automatic load balancing content to users in Europe and USA from two Linux servers located in Milan, Italy, and California, USA. In 1995 it was used to provide on demand and live streaming audio under the name of IRN (Internet Radio NEXUS) to United Nations radio, UNESCO radio and UNEP radio, which were the first users of this technology.

NEXUS later extended its original 2-node concept, adding multiple, redundant nodes in Europe, USA and Asia embedding automatic recovery into the technology. Until 2002 WorldDirector was offered by NEXUS-IBA also to commercial companies to support the association's activities in local and international broadcasting.

In 2002 the technology was transferred for commercial exploitation to Wornex International, a startup spawn from the NEXUS-IBA R&D lab, and made available commercially as a fully managed solution that also included additional features.

Technology
WorldDirector is a proprietary technology based on open source that has been conceived to provide globally distributed and fully redundant content, requiring no content modification of web pages (i.e. no "akamization"), and offers no single point of failure. It was conceived to continue providing delivery of content under a disaster situation (like a catastrofic earthquake or DDoS attack), when both DNS and network connectivity may remain interrupted or disrupted for any period of time. It was also designed to provide fast access to localized content in less developed countries or at the edge of the Internet where connectivity may be scarce, slow or congested.

WorldDirector is currently deployed under two main variants:


 * 1) WorldDirector active CDN: provides total replication and acceleration of content at each node. Each node is independent of the CDN logic and can survive multiple failures at any other node. No central authority, and no central point of failure exists to undermine the possibility of each node to continue providing access to edge content. Under active configuration any N-1 number of WorldDirector nodes can become unavailable (i.e for maintenance) or unreachable (i.e. for network congestion or routing problems), while content still remains available and reachable from any of the servers that are still reachable from the client. Under this configuration nodes (or servers) can be brought down for maintenance, and brought back on-line without any disruption to content delivery.
 * 2) WorldDirector passive CDN: only provides remote (edge) caching and acceleration from one or more origin servers. As with most other CDN implementations, this configuration can fail to provide access to content if the network connection to the origin(s) servers is interrupted or the origin server(s) are down for maintenance.
 * 1) WorldDirector passive CDN: only provides remote (edge) caching and acceleration from one or more origin servers. As with most other CDN implementations, this configuration can fail to provide access to content if the network connection to the origin(s) servers is interrupted or the origin server(s) are down for maintenance.

Comparisons with other CDN Technologies
Most CDN technologies are based on a redirector node placed at a well-connected Point of presence. The redirector must be always reachable and able to sustain any kind of failures or attacks in order for all CDN nodes to deliver content.

However, when problems happen at the redirector node or if the redirector is unreachable from the edge of the Internet due to routing or DDoS issues, all the CDN network become totally or partially unreachable. As such, even if it may be replicated, the redirector may act as a single point of failure for the whole CDN. This may happen, for example, because of a routing problem if the redirectors and/or the caching nodes' routing are managed by a single Autonomous_System_(Internet).

Redirectors also add additional latency, especially for clients at the periphery of the Internet. The WorldDirector technology deployed in the active CDN mode for N nodes (N>=2) are independent from any redirector or any central authority and also each Worlddirector node is independent from one another. As such they can survive network failures while continuing to provide service seamlessly until at least one node is up and reachable.

WorldDirector does not employ redirectors by design, but uses multiple (N>=1) globally redundant autonomous nodes. Another difference with other CDN is that WorldDirector does not employ hundreds or thousands of caching nodes, and as such is easier to administer and has a lower installation and maintenance cost.

Other features
Other features provided inherently by the WorldDirector technology are:


 * Content acceleration (via HTTP compression using standard IETF content encoding)
 * Origin web site isolation and protection against malicious attacks to orgin server(s) by filtering undesired requests at the edge
 * Automatic disaster recovery (in active mode)
 * Locally and globally distributed load balancing
 * Standard edge caching (in passive mode)