This paper presents the architectural details of an evolving open source/open architecture software framework for developing organ-level surgical simulations.Our goal is to facilitate shared development of reusable models, to accommodate heterogeneousmodels of computation, and to provide a framework for interfacing
multiple heterogeneousmodels. The framework provides an application programming interface for interfacing dynamic models defined over spatial domains. It is specifically designed to be independent of the specifics of the modeling methods used, and therefore facilitates seamless integration of heterogeneous models and processes. Furthermore, each model has separate geometries for visualization, simulation, and interfacing, allowing the model developer to choose the most natural geometric representation for each case. Input/output interfaces for visualization and haptics for real-time interactive applications have also been provided.