Workflow for Taverna based on the IMPEx-FP7 method getFieldLine. This method computes field lines or stream lines inside the simulation box. The user will provide a set of 3D position coordinates which act as starting points for the field/stream line tracing. The tracing may be performed forwards, backwards or both. The method will return an URL to a VOTable file which contains the field/stream lines as a set of 3D position coordinates and the requested physical quantities at these points.