WCGI combines the newest innovations with the technology of the old. To what end? CGI is dead. Long live WCGI!
CGI (Common Gateway Interface) was a way for web servers and server-side programs to interact as simple
as taking a request over STDIN and returning a response over STDOUT. The protocol however was inefficient because it required a new process to be respawned each time a page was served. As such it was superseded by technologies which were better, faster, more secure, with better integration with the web server.
One such was FastCGI which was introduced as a middle ground between the PHP Apache Module and the CGI application. It allowed scripts to be executed by an interpreter outside of the web server and included the security benefits of CGI without any of the inefficiencies of CGI. For an example in Java, see Servlets.