PET FMS vs Classic HPC
HLA is a distributed object technology (DOT) for Modeling and Simulations
DATORR effort from Java Grande forum trying to address similar DOT for classic HPCC
RTI is to FMS (event driven simulations) as MPI is to Classic HPC (time-stepped simulations)
WebHLA starts from FMS and can also extend / add value to Classic HPC (most other CTAs)