CGI programming

The IBM® HTTP Server for i supports the extension of the functionality of the HTTP Server through the use of Common Gateway Interface (CGI) programs.

The CGI Process
The basic principle of Common Gateway Interface (CGI) is that a Web server passes client request information to CGI programs in system environment variables (and in some cases through standard input or command line arguments) and all standard output of CGI programs is returned to Web clients.
CGI data conversions
The server can perform ASCII to EBCDIC conversions before sending data to CGI programs. This is needed because the Internet is primarily ASCII-based and the IBM i server is an extended binary-coded decimal interchange code (EBCDIC) server. The server can also perform EBCDIC to ASCII conversions before sending data back to the browser. HTTP and HTML specifications allow you to tag text data with a character set (charset parameter on the Content-Type header). However, this practice is not widely in use today (although technically required for HTTP1.0/1.1 compliance). According to this specification, text data that is not tagged can be assumed to be in the default character set ISO-8859-1 (US-ASCII). The server correlates this character set with ASCII coded character set identifier (CCSID) 819.
Writing high availability CGI programs
High availability CGI programs use APIs to preserve state information. The state information can be accessed by different IBM i servers that are participating as cluster nodes in a clustered environment, even after a failure or switchover of the HTTP Server or IBM i server.
Writing persistent CGI programs
Persistent CGI is an extension to the CGI interface that allows a CGI program to remain active across multiple browser requests and maintain a session with that browser client. This allows files to be left open, the state to be maintained, and long running database transactions to be committed or rolled-back based on end-user input.
CGI programs and activation groups
The following section is intended to give a brief overview of activation groups.
Running CGI programs in IBM PASE for i
The IBM HTTP Server for i Web server can run CGI programs created to run in the IBM Portable Application Solutions Environment for i. In addition, the HTTP Server can also run programs that follow the FastCGI protocol.
Setting up CGI programs for HTTP Server
This topic provides information about how to set up CGI programs for your IBM HTTP Server for i Web server.

Parent topic: Programming