Input from the form is then made available to the CGI program using the Common Gateway Interface Standard. The CGI program can process the input data itself or call on other programs such as database or mainframe interfaces. Thus, information submitted by the form can interact with legacy applications. The CGI program can also dynamically create HTML pages to be passed back to the client. A database search could be conducted using the input fields, for example, and the results passed back to the user in a dynamically generated Web page.
Legacy applications come with a variety of mechanisms for tapping into their data.
These generally involve software which sits on both the mainframe and the Web server machine, each communicating with the other over an acceptable network transport protocol. This is a flavor of SQL initiated by Microsoft. It is more generic than the proprietary SQLs identified above, but it is also generally slower. Thus, greater flexibility is traded for reduced response time. Depending on the expected transaction volume, the slower times may not be noticeable to the average user.