Extensible URI-pattern-based servlet request processing frameworks process and respond to requests for resources sent over a network by client programs to application programs in multi-tiered data processing systems. An extension processor component, an improved web container; and an improved web application architecture form the framework. The extension processor component includes one or more extension processor factories, each of which generates a single type of extension processor to handle specific application components. Each extension processor is adapted to respond to a request having a declared pattern. The extension processor factory resides within the web container and provides a list of patterns for which it is responsible. The extension factory also instantiates an extension processor to respond to a request having a pattern that matches that extension processor's declared pattern. The improved web application includes a request mapper adapted to route a request having a particular pattern to the appropriate extension processor.