GroupWeb: A WWW Browser as Real Time Groupware
Saul Greenberg and Mark Roseman
Department of Computer Science, University of Calgary
Calgary, Alberta CANADA T2N 1N4
Tel: +1-403-220-6087
E-mail: {saul, roseman}@cpsc.ucalgary.ca
ABSTRACT
GroupWeb is a browser that allows group members to visually share
and navigate World Wide Web pages in real time. Its groupware
features include document and view slaving for synchronizing information
sharing, telepointers for enacting gestures, and relaxed "what
you see is what I see" views to handle display differences.
A groupware text editor lets groups create and attach annotations
to pages. An immediate application of GroupWeb is as a presentation
tool for real time distance education and conferencing.
Keywords
Word wide web, groupware, shared visual workspaces.
INTRODUCTION
The World Wide Web is becoming a universal repository for distributed
information, with Web browsers becoming the standard way that
people search for and display items of interests. Although the
information is a shared resource authored by the community, Web
browsers are still single user tools that partition one person
from another.
What if Web browsers were redesigned as groupware that allowed
people to share views of pages? Such a browser would be a valuable
presentation tool for real time distributed meetings for several
reasons. First, relying on a user's established Internet connection
removes the complex telephone setups required by many conferencing
tools. Second, the prevalence of the HTML document standard on
the Web means that a large amount of existing information can
be brought into the meeting. Third, most computer-literate people
are now familiar with the interfaces of Web browsers, so little
training would be required.
A few browsers today provide rudimentary groupware abilities e.g.,
NCSA Mosaic and [1]. Typical features include page synchronization
and chat windows. Drawing on research into groupware workspaces
and shared drawing tools [2], we suggest a set of changes that
can turn Web browsers into excellent presentation tools. These
are described by way of our implementation of GroupWeb, a browser
that allows distributed groups to navigate and share Web pages
in real time.
THE GROUPWEB DESIGN
GroupWeb is built on top of GroupKit, a groupware toolkit [3].
Like normal Web browsers, GroupWeb fetches and displays HTML pages.
However, several people can enter a GroupWeb session via a session
manager (Figure 1f). Each participant runs their own GroupWeb
replica, and the browser becomes a shared visual workspace (Figure
1a). Each replica has independent access to the Web, but they
communicate directly to each other to stay synchronized.
GroupWeb is founded on five design requirements: document slaving
for synchronizing pages, relaxed "what you see is what I
see" views to handle display differences, view slaving for
synchronous scrolling within pages, telepointers for enacting
gestures, and group annotations that can be attached to pages.
Each are described below.
Figure 1. GroupWeb, showing (a) a shared
web page, (b) telepointers, (c) multi-user scrollbars, (d) view-slaving
controls, (e) a group annotation tool, and (f) a session manager
for joining the GroupWeb conference.
Document slaving for synchronizing pages
The most basic act of a presenter is selecting material (a slide
or page) and bringing it to the group's attention. In GroupWeb,
the material is an HTML page that the presenter selects by navigating
a link. GroupWeb guarantees that all the browsers in the session
receive a copy of the page, which we call document slaving. It
does this by instructing all its replicas to fetch the new page,
specified by the HTTP address.
Relaxed "what you see is what I see" views
In face to face meetings, all people see exactly the same thing.
In distributed meetings, a similar effect can be achieved by strict
"what-you-see-is-what-I-see" (or strict-WYSIWIS), where
the visuals are kept identical across all displays. However, display
sizes and personal desires differ, and it may be onerous to impose
this constraint onto distributed meeting participants. GroupWeb
"relaxes" strict-WYSIWIS by permitting windows to be
different sizes, and by reformatting the text to fit the display
nicely. While this means that people may not see exactly the same
thing, it does provide more flexibility for the way each person
wishes to view their page.
View slaving for synchronous scrolling
Most HTML pages require scrolling as they rarely fit completely
within a window. In a shared document, scrolling can be independent
or synchronized. GroupWeb allows both. Independent scrolling,
a form of relaxed-WYSIWIS appropriate for loosely coupled collaborations,
is the default. People can have viewports onto different parts
of the page, with feedback on other's locations shown via multi-user
scrollbars (Figure 1c). Each colored bar represents how much a
particular participant can see, as well as the overlap between
views, if any. Synchronized scrolling, on the other hand, automatically
aligns viewports. To enable this, a menu on each bar is raised
(Figure 1d), with the menu (and the bar's color) identifying the
participant it represents. Selecting "Follow this user"
causes the local display to scroll in synchrony with the other.
Because synchronization is one-way (unless the other person also
slaves the view), the local user can still scroll quickly to other
parts of the page for quick glances.
Gesturing through telepointers
Hand gestures play an important role in any work surface activity,
and presentations are no exception. We use them to enact ideas,
to signal turn-taking, to focus attention of the group, and to
reference objects on the work surface [2]. As with many groupware
workspaces, GroupWeb uses telepointers as a way to transmit and
display gestures (Figure 1b). Because the display is relaxed-WYSIWIS,
telepointers are attached to letter positions rather than Cartesian
coordinates. This means that the pointer will always be over the
same text on all displays.
Attaching group annotations to pages
While the original web document is not editable, people can attach
shared annotations to any page. GroupWeb includes an annotation
tool (Figure 1e), which is a multi-user text editor. Users can
enter and edit text at any time, which is displayed on all screens.
As well, the annotation is automatically keyed to the current
web page. Changing to a new page clears the editor, while returning
to an annotated page restores the text annotation in the editor.
Annotations can be used for almost anything: group note-taking,
collecting comments, suggesting revisions, and chatting.
DISCUSSION AND SUMMARY
We have described a system called GroupWeb which leverages the
ubiquity of the Web by adding features found in real-time groupware
systems. This combination can yield a powerful presentation tool
that could be used for many purposes, including distance education,
distributed meetings, and small group collaboration.
Groupware browsers, however, will have to evolve along with the
capabilities of Web pages. Page synchronization works now because
current pages contain mostly static information. With the recent
introduction of both forms and the Java language, pages will have
to synchronize themselves at the input event level (for forms)
and script execution level (for Java) as well.
REFERENCES
- Dybvik, P. and Lie, H. (1994) Combining real time multimedia
conferencing with hypertext archives in distance education. ACM
SIGRAPH Video Review, 106.
- Greenberg, S., Hayne, S. and Rada, R. (1995) Groupware
for real time drawing: A designer's guide. McGraw-Hill, Europe.
- Roseman, M. and Greenberg, S. (1996) Building real time groupware
with GroupKit, a groupware toolkit. ACM Trans Computer Human
Interaction, in press.
