Web conferencing Part 2: Infrastructure

Learn how Web conferencing systems are designed, how they work and whether they will work for your organisation.

PREVIOUSLY: Web conferencing service selection criteria

Web conferencing refers to a real-time PC-based communications service that broadcasts a presentation or application over IP to a receiving audience. The key features that distinguish Web conferences from other collaboration applications and services are the one-to-many, real-time and PC-based desktop or application broadcast attributes.

Since the early 1990s, one-to-one approximations of Web conferencing, such as screen sharing or remote-control services, have been a practical element of the desktop support engineer's toolkit. Remote-control systems have been limited to desktop support applications for three major reasons:

  • The system architecture was optimised for one-to-one sharing and didn't lend itself well to the one-to-many demands of a broadcast service.
  • The security issues associated with employees downloading remote control applications and sharing their screens with users outside the enterprise security perimeter are risky at best.
  • The support challenges and potential liabilities from creating software conflicts on potential customers' PCs reduced the enthusiasm for applying remote-control software to this need.

The rapid commercialisation of the Internet in 1995, together with improvements in Web browser multimedia capabilities and greater operating system stability, gave rise to the development of effective Web conferencing solutions.

System design

In a Web conferencing system, there are four major components:

  • The publisher controls
  • The hosting server
  • The receiver application
  • An IP network

The publisher and receiver applications are most often downloaded into the Web browser as part of the service initialisation process. These applets are usually secure Java, Flash, QuickTime or ActiveX components.

The publisher controls are software mechanisms available to authenticated presenters. These controls include the control and definition of the range of in-session service options employed, such as screen sharing or PowerPoint sharing, in-meeting chat, and real-time polling. The publisher can also choose to activate the Web conference, which begins the session by broadcasting the defined screen or application with those conference participants formerly in the standby "waiting room." The publisher can choose which of the meeting participants will be the presenter (if not herself) and how that might occur -- in watch-only mode or in shared-control mode.

Publishers typically have access to a screen notation toolkit that enables drawing on the screen. Publishers can circle specific points of interest with thick red or orange lines, for example, or can click to paint pointer arrows on the screen, directing participant attention. Publishers also control an in-window chat application to communicate directly with one or more specific participants, or they can send text messages to the entire audience. All of the participants' names are conveniently listed in the publisher's dashboard.

The hosting server incorporates a portal and a multimedia conferencing server. The portal component provides the scheduling, calendaring, registration, email reminder processes, authentication, receiver system qualification, software download processes, in-session surveys and post-event customer satisfaction surveys. The multimedia conferencing server controls the process for session broadcast, distributing the presentation from one PC to many, and provides the in-session communications controls necessary to transfer publisher responsibility to another participant and power the chat and annotation services.

The hosting server also enforces the commercial boundaries of the Web conferencing service by regulating the number of registrants, participants or minutes consumed, depending on the pricing model used. To the typical participant, the hosting server is a broadcast device, accepting one media stream from the presenting computer and duplicating it for each of the other event participants.

Some implementations also integrate Voice over IP audio streams into the broadcast, while others establish a separate telephone number and passcode process. Some of the reasons for separating voice and data in this implementation are to ensure high audio quality in an unpredictable Internet setting and to ensure that everyone can participate, even without seeing the screen. Of course, separate implementations typically attract higher costs.

The receiver application is the participant's window into the Web conference. This software functionality is downloaded into the browser environment if necessary, after the browser and computer have been properly qualified. If implemented by the hosting server as a persistent client, it will be checked for release level to ensure that the most up-to-date version is installed. Otherwise, a disposable applet, available only in the memory of the browser, is downloaded.

The Internet provides the connectivity linking each of the system components and enables a very scalable implementation. Users behind a firewall or NAT server are using HTTP service on port 80 to connect to the hosting server portal and therefore can easily comply with most corporate firewall security policies.


For scheduled events, participants are invited to register in advance by visiting a predetermined event-specific URL. Here, prospective participants provide contact details validating their interest in the event. This triggers an email with the meeting authentication details and also identifies this participant for the event reminder emails and processes.

At the appointed time, invited participants point their browsers at a Web conference-specific URL where they must identify the meeting ID and password, then answer a few questions to qualify themselves for access to the Web conference session. Generally, the process begins to qualify the users' computer and browser for the most appropriate applet version to complement the browser and browser version. All the necessary software components are automatically downloaded through the browser as a onetime download or as a disposable applet.


Overall, Web conferencing services are particularly popular for inter-company communications, such as a marketing event to educate prospective customers, demonstrate software products and provide rudimentary customer training. Web conferencing services are a rapidly emerging extension of the audio conference and are more convenient and productive than face-to-face presentations and demonstrations with customers.

Web conferencing is not a particularly strong replacement for hands-on customer training, all-day employee collaborations or customer visits. It offers a reliable, high-quality experience best suited for short-duration -- typically one hour -- educational events and product demonstrations early in the sales cycle.

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