Web applications offer a golden opportunity for domain experts who work with XML documents to leverage their domain expertise, their knowledge of document engineering principles, and their skills in XML technology. Current XML technologies provide a full stack of modeling languages, implementation languages, and tools for Web applications that is stable, platform independent, and based on open standards. Combining principles and proven practices from document and software engineering, we identify architectures, modeling techniques, and implementation strategies that let end-user developers who are conversant with XML technologies create their own Web applications.