Simulation challenges in membrane computing

P system simulators are critical tools to enable them as formal modeling framework for real-life applications. Such simulators abstract the concept of P systems in various ways, depending on the needs of the users and the requirements of the specific application. We identify three main levels of abstraction: graphical user interfaces, simulation engines and parallel imple-mentations. In this paper, we survey the state of the art at these levels and discuss the main challenges under consideration for future developments.