In fact the process steps are (typically) split up into two to three main parts:

• Agent modeling and initial individual demand modeling
• Demand optimization process
• Analysis

The reason lies into the fact that some parts of MATSim are implemented in C++ while other parts are written in JAVA.  The MATSim core has been fully ported to JAVA; in consequence, C++ modules are optional.
  Because of the flexible data parsing and data writing functionality of MATSim-T, also external modeling application and modules can be used for MATSim-T.
The Figure shows a typical MATSim-T process. An external synthetic population generation program by Martin Frick was used to create the individuals of the scenario. With other base information about the scenario all those data a filled into MATSim-DB. With MATSim-FUSION modules these data points are connected in an appropriate way such they can now be used to add initial demand for each person of the given population. The resulting Agent-DB (and also the Network-DB) are exported into well defined XML data files. To optimize the demand, these data are then read into another Agent-DB written in C++. After the optimization process of MATSim-EA the resulting demand and the resulting MATSim-EXEC description are written into files again which can be used for analysis.