MPI tags for master-slave communication. If NCM_MPI_CTRL_TAG_CMD is used, the message is a control message.

NCM_MPI_CTRL_SLAVE_INIT must be followed by #NCM_MPI_CTRL_TAG_JOB containing the serialized job.

NCM_MPI_CTRL_SLAVE_WORK must be followed by #NCM_MPI_CTRL_TAG_WORK_INPUT containing the serialized input.

NCM_MPI_CTRL_SLAVE_WORK is followed by #NCM_MPI_CTRL_TAG_WORK_RETURN containing the serialized return.

NCM_MPI_CTRL_SLAVE_FREE does not need to be followed by any message. The slave can be reinitialized with #NCM_MPI_CTRL_SLAVE_INIT.

NCM_MPI_CTRL_SLAVE_KILL should not be followed by any message. The slave will exit.

Slaves receive messages with tags below: - Waits for a message with tag NCM_MPI_CTRL_TAG_CMD: - If the control message is #NCM_MPI_CTRL_SLAVE_INIT, the slave receives #NCM_MPI_CTRL_TAG_JOB with the serialized job. - If the control message is #NCM_MPI_CTRL_SLAVE_WORK, the slave receives #NCM_MPI_CTRL_TAG_WORK_INPUT with the serialized input. - After #NCM_MPI_CTRL_SLAVE_WORK, the slave sends NCM_MPI_CTRL_TAG_WORK_RETURN with the serialized return.