Overview#DirXML command are the output of a DirXML Engine.
When the DirXML Shim sends an DirXML event notification to DirXML Engine, the DirXML Shim is informing the DirXML Engine of a change in data that occurred in the Connected Application. The DirXML Engine then determines, based on configurable DirXML PolicySets/DirXML Rules, which DirXML commands, must be sent to the Identity Vault namespace.
When Identity Manager sends a command to the shim, Identity Manager has already taken an Identity Vault event as input, applied the appropriate DirXML PolicySets/DirXML Rules, and determined that the change in the connected system represented by the DirXML command is necessary.
From the point of view of the overall system, if a DirXML command from one driver on its Publisher Channel is creating or updating an object in the Identity Vault namespace, it might cause events to be submitted on the Subscriber Channels of other DirXML Drivers in the system. This allows changes to cascade, flowing to all Connected Applications.