How Web meeting tools work
Web meeting tools are built using a one-to-many architecture. A one-to-many architecture is defined as an application running on a single host/presenter platform whose output is visually distributed or replicated to the group. The basic shortcoming of the one-to-many architecture is that, for a participant to make an annotation, they have to request keyboard/mouse control and the host/presenter must transfer control.
This requirement dictates at least two, if not more, awkward transactions, which frustrates and inhibits spontaneous collaboration by adding multiple additional clicks. Some vendors have introduced a workaround to minimize this problem: having participants contend with each other for mouse control (that is, whoever's mouse clicks first is the one who gets control). But this workaround becomes a fight for mouse control and is very confusing and disorienting.
Most Web meeting tools offer two modes of sharing: desktop/application sharing and document sharing. The host is the initiator of the meeting and is the only participant who can delegate that role to another participant. The presenter is the participant who has keyboard/mouse control at any time and can reassign keyboard/mouse control to another participant.
Desktop sharing, the first mode, enables a designated participant to have keyboard/mouse control of any application on the presenter's desktop. Application sharing restricts that control to a set of specific applications. Both desktop and application sharing (also called screen sharing) function the same way, so they will be discussed together. When assigned by the presenter, other participants can also manipulate the document by having their client software capture the mouse motion and keyboard entries they make and upload these commands to the server. The server then sends the commands to the workstation where the application actually runs.
When the presenter at the workstation manipulates a document, the updated snapshots of his or her workstation screen are uploaded to a server. The server downloads the screenshots to each of the remote participants. A vendor client viewer is installed on each participant's workstation to decompress and display. The screen snapshot viewer can be either a browser plug-in or a separate application. As the screenshots are received at the participants' workstations, their client software updates the view of what appears on the host/presenter's screen-which sometimes results in an annoying screen flicker.
The second mode of document sharing is designed to avoid the high bandwidth requirements of desktop/application sharing. This scheme uses a virtual printer representation that compresses the complete original document either locally or on a server. The complete document is downloaded to each participant as distinct from desktop/application sharing, which transmits one page at a time. None of these tools cited above support three-dimensional (3D) document collaboration.
All document sharing solutions include a minimal set of annotation tools. Annotations made are replicated to the other participants and applied to an overlay to the virtual representation. Even though each participant's annotations can be saved in a separate file on the collaboration server for some of these solutions, the comments are not applied to the document.