Connecting to a CGI Script
Although an applet can read files from a web server machine, as in, for example, establishing a URL connection and doing getInputStream(). Applets are not allowed to directly write to files on the web server machine by doing getOutputStream(). (Java applications can do this!)
The applet can establish a socket the URL of the web server. Then it uses an OutputStream on the socket to send a message formatted in MIME, just as if it were from the browser. The header of this message requests the web server to run a CGI script. In addition, the applet can send data in the body of the message for the CGI script to read. And the CGI script can send back a MIME message to the applet.