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1.3 Protocol Overview (Synopsis)

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The sequence of messages exchanged by the Remote Desktop Protocol: Display Control Virtual Channel Extension is described in the following figure. The messages exchanged in this diagram are strictly sequential.

The Display Control message sequence

Figure 1: The Display Control message sequence

After the Display Control dynamic virtual channel has been opened, the server communicates display capabilities to the client by sending the DISPLAYCONTROL_CAPS_PDU (section 2.2.2.1) message. This message specifies a set of parameters to which the client is required to adhere when sending the DISPLAYCONTROL_MONITOR_LAYOUT_PDU (section 2.2.2.2) message.

To request a display configuration change on the server (such as the addition of a monitor or a new resolution for an existing monitor), the client sends the DISPLAYCONTROL_MONITOR_LAYOUT_PDU message to the server. If the requested configuration is not possible, or is invalid, the server will not update the remote session with the requested parameters.

Changes in the server-side display configuration occur out of band to the Remote Desktop Protocol: Display Control Virtual Channel Extension. If the requested graphics configuration is valid and can be configured on the server, then the server will either:

  • Initiate a Deactivation-Reactivation Sequence (as specified in [MS-RDPBCGR] section 1.3.1.3) if the Remote Desktop Protocol: Graphics Pipeline Extension is not being used to remote session graphics.

  • Restart the graphics pipeline using the surface management commands (specified in [MS-RDPEGFX] section 1.3) if the Remote Desktop Protocol: Graphics Pipeline Extension is being used to remote session graphics.

The DISPLAYCONTROL_MONITOR_LAYOUT_PDU message can be sent whenever a display configuration change is required.