A basic webserver
- knows how to turn a HTTP get for some URL to a particular document within its docs dir
/path/to/htdocs - has, by convention, a special dir where requests for documents do not yield the document itself but the output of executing that "document"
- the "document" is a binary executable or script
- sub directory name is usually
/cgi-bin
- scripts in
cgi-bin/- STDOUT is sent over the wire to the HTTP client
- Info about the request are stored in the environment that the script inherits.
- In perl this is
%ENV
- The CGI spec defines the headers the script should get by being invoked by the server
- CGI assumes that the web server will fork a new process (duplicate itself, edit environment of the dupe and load new code) to run the script
- This is not super fast as you might imagine
Options for speeding up CGI
- Web server plugin
- does not fork new process to run script
- webserver loads script and interperter into memory at startup (it "preforks")
- examples:
mod_php
- FastCGI
- basically CGI without the requirement that server fork every time
- Replace webserver
- Java does this - the java process acts as web server and "application" runner