In computing, code on demand is a general term for any technology that sends executable software programs from a server computer to a client computer upon request from the client's software (e.g., browser). Originally, the word computing was synonymous with counting and calculating, and a science and technology that deals with the original sense of computing mathematical calculations. ...

Code on demand is a specific use of mobile code. A well-known example for the code on demand paradigm are Java applets: An applet's program code lies inactive on some web server until a user (client) requests a web page that contains a link to the applet using his web browser. Upon this request, the web page and the applet are transported to the user's machine using HTTP. When the page is displayed, the applet is started in the browser and executes locally, inside the user's computer until it is stopped (e.g. by the user leaving the applet's web page). This completes the applet's life cycle. In computer science, mobile code is a general term for any executable software program that is sent via some computer network from one computer to another to be executed at the destination. ... A Java applet is an applet delivered in the form of Java bytecode. ... Wikimedia servers architecture The term Web server can mean one of two things: A computer that is responsible for accepting HTTP requests from clients, which are known as Web browsers, and serving them HTTP responses along with optional data contents, which usually are Web pages such as HTML documents and... An example of a web browser (Mozilla Firefox running under Microsoft Windows). ... HTTP (for HyperText Transfer Protocol) is the primary method used to convey information on the World Wide Web. ...

Note that in most cases, the user is not aware that the Web page is downloaded and is executing mobile code into his/her workstation. The user does not "explicitly" or "intentionally" request the mobile code; nor does the user explicitly or intentionally terminate the mobile code.