2.5.19 Share a Desktop

This use case, illustrated in the following diagram, describes how a protocol client can share a desktop in a conference.

Figure 18: Steps for sharing a desktop

References

• [MS-CONFAS]

• [MS-CONFBAS]

• [MS-ICE2]

• [MS-ICE2BWM]

• [MS-RTASPF]

• [MS-RTP]

• [MS-RTPRADEX]

• [MS-SRTP]

• [MS-SSRTP]

• [MS-SIPRE]

• [MS-SDPEXT]

Preconditions

• The protocol client is present in a Communications Server conference, similar to what is described in section 2.5.17, and is subscribed to conference events, as described in section 2.5.18.

Steps

1. The protocol client sends a SIP INVITE with a media description offer to Communications Server to start an application-sharing session, as described in [MS-SIPRE], [MS-SDPEXT], and [MS-CONFAS].

2. Communications Server sends a SIP 200 OK response to the protocol client with the media description answer, as described in [MS-SIPRE], [MS-SDPEXT], and [MS-CONFAS].

3. Communications Server initiates ICE connectivity tests to the protocol client, as described in [MS-ICE2] and [MS-ICE2BWM].<29>

4. The protocol client sends an ICE connectivity response to Communications Server, as described in [MS-ICE2] and [MS-ICE2BWM].<30>

5. Communications Server sends the conference state change notifications to the client, as described in [MS-SIPRE] and [MS-CONFBAS].

6. The protocol client sends an updated media description offer to Communications Server, as described in [MS-SIPRE], [MS-SDPEXT], and [MS-CONFAS].

7. Communications Server sends the protocol client an updated media description answer, as described in [MS-SIPRE], [MS-SDPEXT], and [MS-CONFAS].

8. Communications Server sends the conference state change notifications regarding user media joining to the protocol client, as described [MS-SIPRE] and [MS-CONFBAS].

9. Communications Server sends a notification to the protocol client that the user's application-sharing media is connected, as described in [MS-SIPRE] and [MS-CONFBAS].

10. Application-sharing data flows between the protocol client and Communications Server, as described in [MS-RTP], [MS-RTPRADEX], [MS-SRTP], [MS-RTASPF], and [MS-SSRTP].

Note: The steps to allocate media ports on the edge protocol server for firewall and NAT traversal are omitted for clarity. These steps are described in see [MS-AVEDGEA], [MS-TURN], and [MS-TURNBWM]

Post-conditions

• Application-sharing data is flowing between the protocol client and Communications Server.