8. Link Programs
Interchange requires a web server that is already installed on a system. It does have an internal server which can be used for administration, testing, and maintenance, but this will not be useful or desirable in a production environment.
As detailed previously, Interchange is always running in the background as a daemon, or resident program. It monitors either a UNIX-domain file-based socket or a series of INET-domain sockets. The small CGI link program, called in the demo simple, is run to connect to one of those sockets and provide the link to a browser.
Note: Since Apache is the most popular web server, these instructions will focus on it. If using another type of web server, some translation of terms may be necessary.
A ScriptAlias or other CGI execution capability is needed to use the link program. (The default ScriptAlias for many web servers is /cgi-bin.) If ExecCGI is set for all directories, then any program ending in a particular file suffix (usually .cgi) will be seen as a CGI program.
Interchange, by convention, names the link program the same name as the catalog ID, though this is not required. In the distribution demo, this would yield a program name or SCRIPT_PATH of /cgi-bin/simple or /simple.cgi. This SCRIPT_PATH can be used to determine which Interchange catalog will be used when the link program is accessed.