SSI is a standard way of including dynamic content in a Web page. Using SSI #echo tags you can include the value of any Control Variable anywhere on the page including inside other HTML tags.
This technique makes design of the control program easy: it just has to update Control Variables when necessary. The Web server substitutes the SSI tags for the actual value of the variable before sending the page to the browser. The browser is completely unaware that this operation has taken place.
This demonstration shows how to monitor and control a device using CGI callbacks. CGI Callbacks give a tight coupling between the control program and the Embedded Control Server. When a CGI request is received a callback routine in the control program is called with the query as a parameter. The control program processes the query and calls the Web server to send a response back.
Vending machine demo shows how a remote device (a simulation of a vending machine) can be monitored and controlled. You must start cgivend on the server first.