I was learning moveit tutorials, but since the moveit full package was not avialbe for pr2 in ros indigo, i can't understand how does the src folders of moveit(eg.movegroupinterface.cpp) and launch file of moveitconfiguration folder(eg.movegroup_interface.launch) are connected and how do the src file is executed when the launch file is launch by using roslanch. And i am not that experienced with launch files, yaml files etc. But learning day by day.