Killer Game Programming in Java

The Client/Server Model

The client/server model is the most common networking architecture employed in distributed applications. A server is a program (or collection of cooperating programs) that provides services and/or manages resources on the behalf of other programs, known as its clients. Figure 29-4 shows a typical client/server environment.

Figure 29-4. A simple client/server

A key advantage of the client/server approach is the ability for the server to control its clients by localizing important processing and data within itself. For example, in online games, decisions about the outcome of a player's actions (e.g., the shooting of a monster) will be made by the server. The alternative is to delegate this to the client's application, which may lead to abuse by hackers.

A central location for client data and processing makes it easier to monitor users, administer them, and charge them for game playing. These are significant benefits for commercial multiplayer gaming.

The server is an arbiter for conflicting client requests. For instance, it's impossible for two clients to update the same data state simultaneously.

Placing state information in one place makes changing it straightforward and avoids inconsistencies arising when updating multiple copies stored on clients.

Concentrating processing on the server side permits the client side to run on a less powerful machine, an important ...