Application%20sharing

1
Application sharing

• Henning Schulzrinne
• Jonathan Lennox
• Jason Nieh
• Ricardo Baratto
• Columbia University

2
Overview

• No good way to share application state in a
  conference
• T.120 does not integrate well with SIP
• proprietary solutions
• treat as video source ? does not deal well with
  windows, user input
• Goal integrate into IETF session architecture
• Assumption treat remote access (vnc, terminal
  server) and sharing as same problem

3
Components

• Session setup
• User input (HMI)
• Screen output to remote users
• Moderating access to input focus (devices)

4
Basic requirements

• F1 application sharing remote desktop
• F2 desktops (screens) windows
• F3 any number of users
• F4 cannot modify applications
• F5 protocol negotiation
• F6 modular architecture

5
Input

• I1 may not have actual device
• I2 private, authenticated,
• I3 at most one simultaneous user typical, but
  not always
• I4 hints (e.g., modal input)
• I5 indicate focus
• I6 relative timing needed (e.g., video games)
• I7 I18N
• I8 Copy-and-paste?

6
Video output

• V1 different resolutions, color depth
• V2 both lossy (e.g., embedded video, CGA) and
  lossless data
• V3 window layering hints
• V4 semi-transparent windows
• V5 relative timing information
• V6 absolute timing information
• V7 variety of encodings
• V8 no assumption of common fonts

7
Audio and full-motion video

• A1 share audio streams, synced to video
• A2 share full-motion window as part of shared
  application
• A3 receiver may choose not to receive
  high-bandwidth components (e.g., motion video
  window during presentation)

8
Transport

• T1 some parts require perfect reliability
• T2 large number of receivers
• T3 heterogeneous bandwidth
• T4 minimize latency
• T5 work well in low- and high-latency
  environments

9
Whats next?

• Is this a problem for MMUSIC or AVT?
• Basic architecture assumption sound?
• SIP (or similar) for session setup
• SDP(ng) for parameter negotiation
• transport RTP as one option?
• keyboard and mouse input
• RTP as well?
• part of signaling? (KPML etc)
• Need to define new payload formats