entire office environment. 15 In contrast
to Rooms, which limits interaction to
the desktop monitor, Kimura leveraged interactive peripheral displays on
the walls of the office, allowing users to
switch between activities while maintaining a peripheral awareness of other
activities in the background.
in Desktop Interfaces
As the user interface in all contemporary OSs (macOS, Windows, Linux)
materialized around the desktop metaphor using overlapping windows,
icons, menus, and a mouse pointer
(also known as the WIMP paradigm),
it was evident this model provided limited explicit support for human activity, including multitasking. Therefore,
many (47%) ACC systems have provided models that integrate support for
activities into the user interface.
For example, the ActivityBar3 (
Figure 5) suggests replacing the Windows
XP Taskbar with an ActivityBar that
gives direct access to switching among
activities. Each activity groups multiple
application windows with associated
resources, such as documents, spreadsheets, Web pages, among others.
Yellow—middleware, file management, and distributed system support.
Cyan—low-level operating system
support, processes, and I/O.
From the figures, we can see the
majority of papers have focused on
end-user applications (45%), user interface management systems (UIMS)
(47%) (magenta), and middleware
technologies (yellow)—especially file
management (42%) and middleware
frameworks (38%). Less focus has been
directed toward more low-level issues
(cyan) like operating systems (6%), processes (3%), and I/O (2%).
From the review, we can identify a
set of common topics and technologies, which we unpack as examples of
core ACC research contributions.
Many (34%) ACC systems were motivat-
ed by providing support for multitask-
ing, which also represents some of the
earliest research in this space. These
systems enabled multitasking by sup-
porting suspension of the current ac-
tivity and resumption of another. This
focus recalls the original study by Ban-
non et al., who argued that a “work-
space system should support digres-
sion while providing […] easy return to
previous activities.” 1 This implies that
people can pause their work on one ac-
tivity and simply save the entire state of
the activity including the configuration
of applications, files, windows, and
other resources. Afterward, they can
easily switch to another activity, thus,
loading the configuration of files, doc-
uments, applications, and collabora-
tive tools associated with that activity.
One of the first ACC technologies
was the ‘Rooms’ system presented by
Xerox PARC in 1987, 7 which was directly motivated by the Bannon et al. study.
Even though this study was based on
observations of users interacting with
a command-line interface (Unix), similar problems of limited support for
multitasking were also observed in the
graphical user interfaces developed at
Xerox PARC. In Rooms, separate windows associated with the same task
could be collated into distinct ‘rooms,’
and users could switch between these
rooms in order to switch tasks. In many
ways, Rooms was the predecessor of
the ‘virtual desktop’ systems we know
today. Kimura is a more recent example
of an ACC system focusing on supporting multitasking by augmenting the
Figure 2. Left: The Activity-Based Computing model. Right: The Unified Activity Management semantic model.
Semantic Model of Unified Activity
or B2B Workflow
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