13.9. Summary

The Symmetrical Proxy design pattern represents the kinds of experiments with design patterns envisioned by Gamma and his associates when they wrote Design Patterns: Elements of Reusable Object-Oriented Software. James Heliotis and Axel Schreiner's key insight is that two sides of a game over the Internet can be played on a client using symmetrical referees and each side pitting a local player against the proxy of an opponent. This is not an isolated solution to any single game, but rather any games played over a network.

Our particular implementation of the design pattern used Flash Media Server 2 to send the moves of each side to the other, and it's doubtful whether Heliotis or Schreiner had a clue about FMS2. Therein lies the strength of the design pattern. Design patterns should represent general solutions to problems and not specific implementations of a solution. Because of the flexibility of the Symmetrical Proxy pattern, we were able to apply it using the Internet communication program of our choosing, rather than one specified by the original designers.