I agree with ajdecon, but I want to add: the highest performing MPI codes scale to hundreds-of-thousands of processing cores. It is used for high performance co

I agree with ajdecon, but I want to add: the highest performing MPI codes scale to hundreds-of-thousands of processing cores. It is used for high performance computing where application writers want to squeeze as much performance as possible from very large, very expensive machines. Technologies such as ZeroMQ and formats such as JSON were not designed for such environments.