QwikChat Video Conferencing Protocol 1.1
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Revision: March, 2002


Steps in connecting two video conferencing clients.

Definitions:

CLIENT1 - the client that wants to connect; 1.2.3.4
CLIENT2 - the client that is being connected to; 4.3.2.1

Available Commands:

Command		Return Codes		Short Description
---------------------------------------------------------
HELO		201; 501		greeting message
STAT		202; 502		user's status
SEND		203			unreliable transmit
CONN		303; 503		connect
DCON		304			disconnect
QUIT		421			quit


Return Code Summary:

100s - strictly information message (not shown to user)
200s - major messages (not necessarily shown to user)
300s - control messages (not shown to user)
400s - temporary warning messages
500s - fatal errors (shown to user)

Compatability, Legacy, etc.

Upon connecting, a 100 code is sent out to make sure that only
QCVC clients connect. A 421 is used for disconnects because it
conforms with several other protocols used on the Internet,
including FTP and SMTP, to mean a closing of the connection.
Thus, a 421 upon connect will tell all clients that service is
not available, for whatever reason.

Sequence:

First, CLIENT1 attempts to connect to CLIENT2 via its IP address.
If it fails, an error is thrown, and the connection is aborted.

If CLIENT1 successfully connects to CLIENT2, then CLIENT2 will greet
CLIENT1 on the socket by sending the 100 connection greeting message.
CLIENT1 can close the connection anytime by sending a QUIT command, and
CLIENT2 can close the connection anytime by sending a 421 error message.

CLIENT2 <<< 100 QCVC/1.0
CLIENT1 >>> HELO joe@4.3.2.1
CLIENT2 <<< 201 joe is here
 or
CLIENT2 <<< 501 joe is not here

The HELO command is used to establish whether the specified user exists
at the specified IP address. Then the handshake can continue appropriately.

CLIENT1 >>> STAT joe@4.3.2.1
CLIENT2 <<< 202 online
 or
CLIENT2 <<< 202 away
 or
CLIENT2 <<< 202 busy
 or
CLIENT2 <<< 402 status not available (non-fatal error)

Implementations are free to create more locale-specific extensions to
the STAT (status) command.

CLIENT1 >>> CONN video joe@4.3.2.1
CLIENT2 <<< 303 video 11000
 or
CLIENT2 <<< 503 error; explain here...

Lets first explain the CONN (connect) command. It takes two arguments, the
first being the type of service that is going to be established (audio, video
etc.), and the second is the standard username@ipaddress format. The 303
return code means that the service "video" is available on UDP port 11000.
In the future, it may be changed to "udp/11000" to signify the UDP port in
order to accomodate the possibility of TCP ports.

CLIENT1 >>> DCON video joe@4.3.2.1
CLIENT2 <<< 304 video disconnected


The above are the basics of a QCVC implementation.

Supplementary Commands:

The following supplementary commands allow implementations to extend the basic
functionality.

CLIENT1 >>> GETP video rate
CLIENT2 <<< 310 video 30

CLIENT1 >>> SETP video rate 10
CLIENT2 <<< 310 video 10
 or
CLIENT2 <<< 510 video 10 could not set frame rate

The above is sufficient for setting the options. Connection parameters include:
rate, compression

The SEND command can be used for unreliable communications that return nothing,
such as chat messages between two users.

CLIENT1 >>> SEND chat Hello Joe!

Here, CLIENT2 does not return any error code or message, hence the unreliability
of the command. The message is not guaranteed to be delivered correctly, or even
at all. On the receiving end, if a user wishes to send a chat message, then the
server (CLIENT2) will return an error code to the "true" client. For instance, if
the other user wishes to send the same exact message:

CLIENT2 <<< 203 chat Hello Joe!


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QwikChat Video Conferencing Protocol 1.1
(C) 2002-2004 Amir Malik. All Rights Reserved.

http://qwikchat.virusexperts.com/qcvc/