The Common Gateway Interface (CGI) is a standard for data transfer between WWW browsers (clients) and WWW servers. CGI provides a mechanism for clients (typically using a WWW Browser) to invoke executable programs on a WWW server.
Data summation, data retrieval, file access, or database access in a business system that was constructed using the Internet or running on a local Intranet cannot be achieved when using only static HTML documents (Web pages) with a WWW server.
To support the above requirements, external COBOL applications or other tools musts be used. Such external COBOL applications running in conjunction with a WWW Server are called Web applications.
A Web application may consist of one or many programs. When using CGI, a main program is invoked on a WWW Server as a result of a request received from a client. This main program must be in .EXE format. When using NetCOBOL, you may, however, segment a Web application by using .DLL files as subprograms. DLL's, however, cannot be invoked directly from a client using an HTTP page.
This chapter:
describes the CGI processing flow, and
gives an overview of NetCOBOL CGI subroutines.
