Killer Game Programming in Java

The Peer-to-Peer Model

Peer-to-peer (P2P) encourages users to share their resources with others; resources include hard-disk storage, CPU time, and files (audio, video). This is different from today's Web/Internet in which business/government/university servers present information, and the rest of us read it. The difference is illustrated by Figure 29-5.

Figure 29-5. Client/server versus P2P

P2P isn't a new idea: the early Internet (at that time, the ARPANET) was designed to be P2P so U.S. universities and government installations could share computing resources.

Many of the killer apps of the 1980s, such as Telnet and email, were client/server-based but their usage patterns were symmetric—i.e., most machines ran clients and servers. Usenet (net news) is a P2P application: it employs a decentralized file-sharing model for distributing news, but an unofficial backbone has developed over time, based around server inequalities in storage capacity, processing speeds, and network connectivity.

Things started to change with the growth of the Web. It's a client/server model like most of the earlier applications, but differences lie in its political and social components. Most users only browse the Web; they don't run their own web servers. This is due to the user's lack of technical knowledge, the difficulty of setting up a server, and because commercial ISPs prohibit server installation. Many ...