Collaborative VNC (v.0.5.1)

What is Collaborative VNC?

Collaborative VNC lets you share a computer desktop between multiple people, who can each be all the way across the Internet from each other. Everyone can see everyone else's mouse pointers, and you can take turns controlling the desktop, so that everyone is not clicking on everyone else's toes all the time.

It should be noted that Collaborative VNC is really only a prototype at this stage. Be aware that this code is not production quality. I'm looking forward to rewriting it at a patch to some more portable vnc implementation. But for now, if you find problems with it, please let me know!

Where is Collaborative VNC?

My current patch to VNC is here. It should be applied to TightVNC for unix/linux version 1.2.9 with the command `patch -p1 < ../vnc-collaborate5.1.diff` from within the un-tgz'ed vnc_unixsrc directory, and with the diff in the same directory that the vnc_unixsrc is in.

What does Collaborative VNC do?

Multiple Mouse Pointers (Sort of)

With Collaborative VNC, when multiple people connect to one desktop, you can see everyone else's mouse pointer. As of version 0.5, each user's mouse pointer (besides your own) is labelled with that user's name. Everyone can move their own pointer independently from the others, although only one mouse at a time can actually interact with the desktop. Every member (every instance of vncviewer) connected to any given desktop (Xvnc session) gets a different colored mouse pointer. The first 8 members each get unique colors, and then it begins recycling.

(If you think you can come up with a larger, better set of colors that are easily distinguishable, please tell me!)

Floor Passing: Controlling Who's in Control

With Collaborative VNC, you have control over who "has the floor" (is controlling the desktop). You can set it up in many ways, ranging from a setup where everyone can take control whenever they want, to a setup where whoever has control keeps it until they decide to give it up.

At most, one member at a time "has the floor" (is in control) on any given Xvnc session. Only the member who has the floor can control this session. The first member to join an empty session is given the floor.
A member who does not have the floor can try to take the floor by clicking the mouse in the session. If the member who has the floor has been inactive for a few seconds (this duration is configurable), the new member is given the floor.
Members can also request the floor by pressing the F9 key, or pressing the F8 key to get the vncviewer menu, and then choosing their own name from the member list.
The member who has the floor can pass control directly to another member at any time by pressing the F8 key to get the vncviewer menu, and then choosing the name of the person they want to have control.
The member who has the floor can also manually release it at any time by pressing the F9 key, or pressing the F8 key to get the vncviewer menu, and then choosing their own name in the member list. Once released, anyone can take control just by clicking.
You can also designate one member the 'master'. The master has the ability to take control, or give control, to or from anyone at any time.

The Member List in the Menu

When you pop up the VNC menu by pressing the F8 key, the bottom part of this menu contains a list of the names of all the members of this desktop. Clicking on a name gives that person control.

When you have the floor, you can give control to anyone.
When you do not have control, you can only try to give control to yourself. The other name-menu-items are disabled in this case.
If you are the master, you can give control to anyone, whether or not you have the floor.

Command-line Options

Xvnc -collaborate command-line flag. (Can also be passed to vncserver.)
When you run a vnc server in -collaborate mode, all of the following functional changes apply.
Xvnc -mergekeyboards flag. (Can also be passed to vncserver)
With this flag enabled, every member connected to an Xvnc session can send keystrokes all of the time. Without this flag, only the member who is currently in control of the session can send keystrokes.
Xvnc -master flag. (Can also be passed to vncserver)
With this flag set, the first member to join the session becomes the master. The master is always able to take control of the session, in case someone else with a high -autoreleasedelay is not good at sharing. This is especially useful when combined with -noautorelease.
vncviewer -name NAME option.
This tells the viewer to tell the server what your name is, so that all of the other members can see the name of who has the floor. This defaults to the username of the user running vncviewer. If there is already a member with this name connected, Collaborative VNC appends a dash and a unique number to the end of your name.
vncviewer -autoreleasedelay SECONDS option.
When you have the floor, and another member is trying to take control, your vncviewer will automatically release the floor if you have not pressed a key, released a key, or had any mouse buttons down for this number of seconds. 2 is the default.
vncviewer -noautorelease option.
Never automatically release the floor. (See previous point.)
vncviewer -nopopups flag.
When a member takes control of the session, vncviewer will normally show you the name of the newly in-control member for 2 seconds in the top-left corner of the session. This flag tells the viewer not to do this.
vncserver -exec 'command' option.
This lets you start up the Xvnc session and immediately start your command (mozilla, for example). Then when the command finishes, the Xvnc session is automatically closed down for you.
All components of this patched version of Vnc will cooperate with unpatched versions of TightVNC that use rfb protocol 3.3 or earlier (only tested with 1.2.8 and 1.2.9 on linux and windows)

Why would I want to use it?

It makes shared vnc sessions work much more smoothly. And being able to see everyone else's mouse pointers can add a much needed method of spatial communication. It can also be nice for demos where you want one person in control, and everyone else to be able to point as they ask questions. (Use vncviewer -autoreleasedelay -1 to disable automatically giving up control.)

I also think it could be useful as a way to work remotely with others. Try opening up one Xvnc session per application you're sharing. Maximize each the shared application to make it fill its Xvnc desktop. Now each person can be in control of a different app, and you can easily pass control of the apps around. So two people could take turns editing, and watching/pointing in an emacs window, while someone else looks up info in a mozilla window. Then someone could take control of the mozilla window, copy some text from it, take control of the emacs window and copy it into there...

Todo List

These are lots of things I still want to do with this project. And I'm doing them! With various speeds and intensities. This list is much shorter than it was in January... But I'd like to grow this list with new ideas so I can keep choosing the coolest and most fun tasks to work on.

add a command-line switch to turn off labelling of mouse pointers
add color to the member menu items
add the ability for the master to designate other members as masters (think operators in IRC)
let members choose their own colors
make keystrokes request the floor, similar to how mouse clicks do now
continue tweaking the look and feel of the menu
more code cleanup
patch the java viewer to work with Collaborative VNC
patch the windows viewer to work with Collaborative VNC

Contact Me

Feel free to email me with questions, comments, feature requests, etc. at levittben at yahoo com. (Please excuse the low-tech and inaccurate obfuscation.)