Object-oriented approach to crop modeling: Concepts and Issues

This research was initiated to learn what the crop modeling community could do to facilitate an evolution from existing crop models toward more modular ones that can meet increasing demands. Specific objectives are to 1) use UML to design and implement a modular crop model using an object oriented language, and 2) to compare the characteristics of this model and its development with a modular model written in FORTRAN. To better understand issues and challenges of using an object oriented (OO) paradigm relative to a Fortran-based model, we investigated the process with a simple, generic crop model. The complexity of the model is minimal hence allowing the focus to be more on model structure (the real issue) instead of the model itself. Two critical issues were considered throughout this study: 1) the exchangeability of modules and 2) the independence of the structure from a specific programming language. From our experience of converting a simple crop model developed in FORTRAN into an object-oriented environment we found that UML can be useful to bring modelers to discuss modeling issues without considering any particular programming language. Modelers can exchange diagrams and convert them into particular programming languages.