The area of web-based simulation has thrived primarily on novel methods for executing models, with contributions to both client and server side applications based in Java and other web-accessible languages. However, there has not been a commensurate degree of research in the area of model design, and in the dissemination of models over the web to support discrete event simulation. For a web-based modeling framework to succeed, that framework must support at least one markup language for specifying model content, as well as methods for converting the markup to a programming language, which is used to simulate the model. We present such a framework, called rube , and focus on a two-stage translation process from one markup language (MXL) to another (DXL), with a final process to create either Java or Javascript target code. This framework has allowed us to leverage the eXtensible Markup Language (XML) for capturing the dynamics of a small number of key modeling types commonly found in computer simulation applications. Our approach allows us to achieve customization of a model's appearance, as well to obtain the transformative benefits of specifying model information within an XML format.