Today, cooperative engineering in the fields of plant production is a time consuming and expensive issue. TI1e integration process of product data and models into the planning and engineering of the production facilities and vice versa is a complex task. Furthermore, these integration processes are repeated in an iterative manner at every level or phase of the plant production project in a supply network of suppliers, turnkey suppliers and manufacturers. The diversity of planning, design and simulation tools, as well as their varying model structures result in completely different interfaces. The globally located cooperation partners and the highly distlibuted sub-models throughout the supply network cannot be integrated into one complete model. As a result, a consistent digital representation of the complete production facility is not available, nowadays. Against this background, a new web service ba~ed platform providing developed methods for cooperative plant production within vi1tual engineering is presented in this paper. It supports the protection of knowledge as well as efficient role and project dependent encrypted data exchange with a definable level of security based on XML. An integration into an existing legacy software architecture is exemplified with popular engineering software.