2. HOW MUCH USE CAN THE APPLICATION SUPPORT?
(See part 1.)
The architecture of Croquet is very different from that of, for example, J2EE applications. In a client-server application, one server or server “farm” must process each and every interaction initiated by the thousands or millions of users. The only thing processed on the end-user’s computer may be as little as the HTML formatting of the text and image results. Every single other computation must be handled on the big-iron servers. To double the number of users, the capacity of the servers must be doubled. It should be no surprise, then, that so much effort goes into trying to squeeze out each available computing cycle in such architectures.
When an application has state — that is, when results depend on previous results rather than simply generating static files — client-server does MUCH worse. The amount of storage required can go up much faster. In some cases the application state depends on the number of possible connections between users or between applications. The storage (and certain kinds of search-like operations) increases as the square of the number of users or applications (N^2, c.f. Metcalfe’s law). But we are particularly interested in allowing students and faculty to form their own ad-hoc groups among which to communicate and solve problems. A client-server architecture hosting such “group forming” applications would grow exponentially to the number of users (2^N, c.f. Reed’s 3rd law). With only a few users, this architecture would not work at all, no matter how (finitely) fast the servers, or what language the application is written in. (See Reed’s discussion for a surprisingly accessible treatment of value, saturation, and other issues.)
