Nearly all client/server applications built today are supported across the Internet. Most of these applications are built around web servers, such as Internet Information Server, and web browsers, such as Internet Explorer. However, some functions require special-purpose applications that use the Internet to transfer data between applications. For example, custom programs can perform functions like synchronizing clocks and exchanging real-time information.
I’ll begin this chapter with a brief review of the requirements for communicating over the Internet, including IP addresses, domain names, port numbers, protocols, and URLs. Then I’ll quickly go over the workings of the two protocols that Visual Basic’s Internet Transfer control supports: FTP and HTTP. The remainder of the chapter is devoted to using the Internet Transfer control.