Those of you who are former Greek scholars know the story of King Gordius of Phrygia, who tied an intricate knot that no one could untie. An oracle said that whoever could untie it would become ruler of Asia. An arrogant young boy came along and resolved the issue of the knot. He did not play by the rules that everyone else used. He took out a sword and cut the knot. The boy was known as Alexander the Great—and he did become the ruler of Asia.
Mainframe applications have become a knot in many businesses. It is a rather nasty knot: spaghetti code covered with sweat, blood, and tears. Our sword to cut the knot is called client-server architecture. We will implement a minor variation of this architecture that I call client-mainframe architecture.