We describe the language and tool Angie for the type-safe specification of Web presentation layers and the subsequent generation of an executable interface prototype. A textual description of a Web based dialogue can be directly expressed in the proposed language and is then automatically mapped onto a system structure in compliance with currently discussed Web design patterns like the Model 2 architecture. The Angie tool bridges between specification and implementation level in a different way than other approaches in the same area. The proposed language directly supports the system metaphor of form-oriented analysis, namely the system model as a bipartite state machine.