The Simile visual modelling environment

Simile is a visual modelling environment that has been developed to overcome the problems involved in implementing agroecological simulation models using conventional programming languages: problems such as the effort and skill needed to program the models, the lack of transparency in models implemented as programs, and the lack of re-useability of models and submodels. It combines the familiar System Dynamics (compartment-flow) paradigm with an object-based paradigm, allowing many forms of disaggregation to be handled, as well as spatial modelling and individual-based modelling. Its visual modelling interface makes it accessible to non-programmers, at the same time allowing models to be largely self-documenting. Models can be run very efficiently as compiled C++ programs, and users can develop new visualisation tools for displaying model results. Simile has been used in international research programmes, including the modelling of Mediterranean vegetation dynamics and modelling the interaction between households and land at the forest margin in developing countries. Simile has been developed in a spirit of open standards for model sharing. Models are saved as a text file in a structured format, with a view to enable model sharing with other modelling environments and to encourage others to develop additional tools for working with models.