Forms and Server Programming

The true power of Web technology comes from the ability of the server to execute a program rather than just serving an existing document file. All of the popular servers support something called CGI for Common Gateway Interface. This is a mechanism for executing an arbitrary program and serving the output of that program back to a client. To do this, the server is configured so that a URL requesting certain document paths is interpreted as a request to execute a program. Different servers manage this in different ways, but essentially either all the files in a particular directory on the server are designated as executables, or the server interprets certain filename suffixes (e.g., .exe) to mean that the file should be executed rather than served as a document.

One of the ways that a browser requests a program execution rather than a document is through the use of an HTML form. An HTML form is a document that contains HTML tags that display various controls for entering data such as text boxes, radio or command buttons, and lists. The form also contains a URL that specifies the program to execute to analyze and respond to the data entered into the form.

For a demo of HTML forms capabilities, use this URL: http://www.mmcom.com/demos/FormDemo.html

Another way to invoke a program execution instead of a document access is through various search requests.