TerraML – A Cell-Based Modeling Language for an Open-Source GIS Library

1. Introduction TerraLib Modeling Language (TerraML) is a spatial dynamic modeling language to simulate dynamic processes in environmental applications. TerraML provides an interface (front-end) from which the end-user can access software components provided by an open-source GIS library called TerraLib (back-end). We decided to implement dynamic models as software components with the objectives of incorporating new functionalities via a flexible and interoperable way, and achieving a tightly coupled integration between the dynamic model and the geographic data. In TerraML we represent space as a cellular model, and represent time as a linear flow divided into discrete intervals. The dynamic model is described by transitions and constraints, where the transition concept corresponds to similar concepts on finite state machines and active databases theories. TerraML is based on XML (eXtensible Markup Language), which is a metalanguage , i.e., a language to create other markup 1 languages. [1] Figure 1 shows the TerraML Simplified Schema using the XML graphic notation [2]. A program written in TerraML has a main section called Cellular Processor, which is divided in 5 subsections: input, 1 In a markup language (tag-set) each element is delimited by starting (< >) and ending (</ >) tags.