1. A computer-implemented method comprising: at a server computer, compiling a fact base and a set of business rules in accordance with a first platform definition model to derive a pre-compiled platform-specific fact base and a set of pre-compiled platform-specific business rules suitable for evaluation and execution by a client-side business rule engine configured to operate as an extension of a browser application consistent with the first platform definition model; compiling the fact base and the set of business rules in accordance with a second platform definition model to derive a second pre-compiled platform-specific fact base and a second set of pre-compiled platform-specific business rules suitable for evaluation and execution by a second client-side business rule engine configured to operate as the extension of the browser application consistent with the second platform definition model; receiving from the browser application an attribute indicative of one of the first platform definition model and the second platform definition model; and communicating to the browser application, in accordance with the attribute, one of the client-side business rule engine and the second client-side business rule engine, a subset of one of the pre-compiled platform-specific fact base and the second pre-compiled platform-specific fact base, and a subset of one of the pre-compiled platform-specific business rules and the second pre-compiled platform-specific business rules, so as to enable the client-side business rule engine to evaluate and execute the subset of the one of the pre-compiled platform-specific business rules and the second pre-compiled platform-specific business rules at a client computer executing the browser application.