In a distributed data processing domain including a plurality of data processing nodes, a simulation data processing node is operated as a participant in a simulation testing of a node operation to determine a simulation job and a simulation command responsive to the simulation testing of the node operation. The simulation job is indicative of one or more actions to be performed by the simulation data processing node as a function of the simulation testing of the node operation, and the simulation command is indicative of a message format for a simulated message representative of simulation job, whereby the simulation data processing node builds the simulated message based on the simulation job and the simulation command.