The study of scheduling algorithms for parallel tasks in a grid computing context either neglects local reservation systems which manage parallel resources, either suppose that they use a First Come First Served strategy, or the experimental model does not handle parallel tasks. In this report, we describe an API built in the grid simulation tool Simgrid. It offers core functionalities to simulate in a realistic way parallel resources and batch reservation systems. Simbatch simulation experiments show an error rate inferior to 1% compared to real life experiments conducted with the OAR batch manager.