Application and Desktop Sharing

Application and Desktop SharingApplication and Desktop SharingOmer Boyaci, Henning Schulzrinne, Department of Computer Science, Columbia University

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23

4

Participant ParticipantHost

Application specific+ Efficient- Participants need application- Application has to be modifiedGeneric- Inefficient (sometimes)+ Participants don't need application+ All applications are supported

•Sharing an application with multiple users•There is only one copy of the application•Participants do not need application itself•Briefly, participants

•receive screen updates•send keyboard and mouse events

Related Work

UltraVNC

MASTMulticast ApplicationSharing ToolX 320,340

Y 100,200Kernel space

User space X 320,340Y 100,200

X 320,340Y 100,200

X 320,340Y 100,200

Mirror Driver

2X 300,500Y 200,600

Server Main Thread

Window coordinates

•Participants may have different bandwidths•Some participants may join lately.•The effects of packet losses•Reliable multicasting (NACK)•Some regions require different encoding

Region>40,000px

?

YES

New Region

?

NO

Use DetectedFormat

YES

-1,0,1

coordinates

PNG Size

Time Stamp

counter

Region recordCreate a record&

Start Checking

Detected?

Continue Checking

NO YES

PNG/JPG Detection Algorithm

What is Application Sharing?

ChallengesWindows Server Architecture

Application Sharing Models

Multimedia Support The effect of Packet Loss

RetransmissionsNACK mechanism for lost packetsNACK suppression for multicasting

Minimizing the loss effectSmall PNG imagesAround 1500 bytesSeveral scan lines