Scaling for Large Chat Sites

More General Issues about Distributed Serving
Fanout Servers
Resources

Fanout Servers

Fanout servers are simply additional copies of Web Crossing which handle the load of additional chatters when you reach the limit of either server capabilities or TCP/IP sockets per "process" (i.e. running program) on the operating system of your server.

For instance, if you had a version of Unix that only supports 256 TCP/IP sockets per process, and you had 300 chatters, you would need a fanout server to handle the additional people.

Or if you were having performance problems with one physical server (computer) and wanted to split up the load over one or more additional computers, you could use one or more fanout servers.

Note: The ability to scale chat users providers nearly unlimited capacity for large numbers of users. Chats with thousands of simultaneous users have been held, and it is estimated that as many 200,000 simultaneous chat users can be supported on a system with sufficient bandwidth and fanout servers.

Depending on your setup and your needs, fanout servers can be set up on the same computer as the first copy of Web Crossing, or on another computer which is networked to the first server.

Figure 1 - fanout server setup options

On a different physical server:
  • Different IP address
  • Can use either DWS or CGI mode
    • On the same physical server:

  • Different IP addresses
  • CGI mode
  • If server supports multihoming, no need for unique ports in fanout server setup form

  • Different IP addresses
  • DWS mode
  • No need for unique ports in fanout server setup form

  • Same IP address
  • CGI mode: different Web Crossing script name
  • Assign unique ports on the fanout server setup form

  • Same IP address
  • DWS mode: server web port other than 80
  • Assign unique ports on the fanout server setup form

    • Consult the Sysop Documentation for more details on all of this.

    When you have the additional copies of Web Crossing set up in their new locations, go, in each, to the Control Panel > Chat Services. Click on the link at the top of that page to get to the more extensive Chat Services page.

    Fill in the port numbers and the IP numbers of the fanout server and Control Room server (the original Web Crossing server) as appropriate.

    Due to Java security issues, you'll need to specify a chat applet download area - one which resides within the IP address you've specified for that fanout server - for each fanout server. If you've used the default configuration, the WBChat directory will be within your Images directory.

    Note that you don't need additional license certificates for the additional copies of Web Crossing - the fanout servers will all use the certificate of the Control Room server.

    Resources

    See the more general information on Scaling, Mirroring, and Distributed Serving

    Sysop Documentation

    Sysop Control Panel

    Web Crossing FAQ