Martin Röscheisen, Christian Mogensen, and Terry Winograd
Computer Science Department
Stanford University, Stanford, CA 94305, U.S.A.
{rmr,mogens,winograd}@cs.stanford.edu
Shared annotations associated with networked information resources
allow people to communicate about what they see and read. Potential
applications include workgroup interaction, newsgroup-like fora, and
personal information management, and can also provide the platform for
reviewed information like Consumer Reports attached to product
descriptions, "Seals of Approval" (SOAPs), or filters in support of
enabling people to make sense of whatever information is presented to
them. A general annotation facility would enable people to annotate
arbitrary documents at any position in-place, to share
comments/pointers with other people (either publicly or privately),
create shared "landmark" reference points in the information space.
Previous systems include the annotations facility in Lotus Notes
(which requires making available ``hooks'' for annotation attachment
in a given document), annotations in Acrobat (which are in-place but not
shared), and various other in-place facilities which are based on a
shared file system to allow multiple people to share comments;
examples here include ForComment, and some versions
of MS Word-both are not incremental, that is, only one user
can write comments at a given time, and then pass on this right. Then,
there is a range of work on conferencing systems, which can
be seen as commenting systems, usually with some dialogue model.
Since its beginning, the World-Wide Web (WWW) has featured as one of
the obvious platforms where group commenting might be able to
flourish, but apart from an early experiment in NCSA Mosaic with a
group annotation facility [2] (which was neither in-place nor designed
in a way that scaled with the volume annotations), there are only
personal annotations in most currently available browsers-and there
is little indication that these are widely used.
In [1], we have described an architecture and the corresponding
protocols for a generic group commenting system which has been
prototyped for the World-Wide Web:
The architecture is based on "annotation sets". Every annotation
belongs to a particular set and annotates a particular page at some
specific location. Every set is associated with a particular server
("annotation server") and identity (like a URL). The server holds the
index (but not necessarily the contents) of all the annotations in the
set, and will in general be distinct from the server which provides
the annotated document. Access control is managed per annotation set;
examples include private, workgroup, or public annotations.
In this paper, we survey some of
the interaction design issues encountered. In particular, the visual
rendering and the interaction models.
Annotations can be indicated in the interface in a number of ways,
including marginal markings (as in LaTeX), format-marking of annotated
text (as in WWW browsers with underlined anchors), in-line
presentation of the annotation text, and in-place annotation
indicators. We are experimenting with several of these. The current
browser uses in-place markers, with character-size in-lined images
marking annotation points, and optional highlighting of the annotated
text element. The choice of marker image can be user-determined,
depending on the perspective a user wants to gain on the ensemble of
annotations: if interested in the author, the image can show the
author's face or individual icon; if the identity of the group sharing
the annotations is more central, then the images can be chosen to
contain a small icon representing the annotation set. Note that although the
images are sometimes only 16x22 pixels, informal experiments confirmed
sufficient discriminability and identifiability.
The annotation icons themselves are ``hot'' links: if clicked with the
left mouse button (which is the Mosaic convention), a full document
view of the comment is displayed. This view may contain other images
of the author (in larger size) as well as further links, for instance,
to longer elaborations; it may also contain further annotations
or follow-up comments (see below).
Annotations can also be examined with a lightweight viewer which pops
up a small window (which looks like a PostIt) when the icon is
selected with the middle button and removes it when the button is
released. This tool is a generic meta viewer which can be used in a
variety of contexts to get "preview" information faster than it is
possible with a full document-view window. It is useful as a general
interface augmentation for mosaic browsers in contexts such as
examining whether or not to follow a hyperlink which might lead to an
expensive document.
We have identified a number of different interaction models, each with its
own specific structure and corresponding interface affordances:
In the initial browser design, the interface reflected the generality
of the annotation mechanism in that it was possible to annotate basically
anything anywhere in any order. This turned out to be confusing for
the most common usages.
For example, there are lots of ways conceivable in which one
could reply to an annotation made by someone else-but if
there is no structural guidance for such a comment
of type "reply", then this will easily become confusing for
subsequent readers.
This led us to rephrase the problem of ``annotating a document'' to
that of ``commenting to someone'' (constrained by certain discourse
structures). To support one common usage, we restricted the
affordances which the interface primarily suggests to a structure in
which there are basically two phases in a specific annotation
dialogue: the first comment (type: annotation) is pinpointing a
particular segment in some document which someone considers worth a
comment-this annotation now opens a discourse thread which is of
type dialogue (enabling affordances for reply, follow-up, etc.). In
other words, all future comments on this point are treated as
follow-ups, and are rendered in the sequentiality of their submission,
giving the functionality of news-group-like discussions. We are
thinking of possibly extending the current implementation with some
synchronous communication features more in the spirit of MUDs, in
which the commenting can be done synchronously among on-line users.
In order to navigate a large distributed web of documents, it is useful to
have ``landmarks'', that is, places which people are familiar
with and which they choose as reference points.
The annotation mechanism can be used to generalize existing concepts
used on the WWW such as the notion of ``hotlists''. Leaving a mark on
interesting documents and then querying the annotation server for a
list of these annotations, in fact provides a ``hotlist'', which can
be shared. The fact
that this is embedded in a generic mechanism (with all other searching
and cataloguing functionality available) in conjunction with being more
dynamic (for instance, 'most recent' queries are possible which give
only the recently modified part of a structure) makes it even more
useful.
Landmarks are particularly useful in combination with a tour mechanism
which we have implemented.
One of the problems with comments about distributed documents is that
they disappear from a user's world unless the annotated document
happens to be looked at.
The overall design in [1] allows us to provide users with ``tour''
facilities which guide them through a tour of all annotations
which fulfill certain filtering properties.
One of the obvious uses are ``What's Up''-type queries: at a given
time a user might want to know what has happened in the time between
now and the last time. Examples include making a tour through all of
the comments which are replies to a particular group member's original
comments.
The tour mechanism is currently implemented simply as a (specifically
typed) list of links for each comment thread and a two-pane browsing interface
such that the tour context is always maintained in one view
and the tour focus is rendered in the other view (e.g. the annotated
document with the comment included). Each such tour link will bring
the user to where the comment in the annotated page is located. This
greatly extends the value of the annotations, since it enables users
to find annotations that are distributed over a number of documents,
without needing to check for changes all the pages of those documents.
We are investigating the advantages of more sophisticated graphical
visualizations, such as maps.
The same underlying mechanism used to store and provide annotations is used
to maintain individual user profiles [1]. This allows for all of
the user specific information to be stored remotely in a profile such
that people can use browsers on different machines with distinct file
systems and load their profile from a server.
This profile is an extensible model of the user's context which also
includes all the information necessary to hide authentication
processes from the user.
The design gives people a presence in the virtual document space:
users can make themselves present at certain document locations
(e.g. by putting their face icon at the top of the page), and
with user profiles stored on a persistent server ``base station'',
they can also be contacted there at any time. This provides a foundation
as an enabling platform for experiments with on-line communities.
Augmenting widely used browsers by facilities that allow not only to
read documents, but also to communicate about them with other people
opens up the possibility of a uniform interface to a variety of
navigational, retrieval, and communication tasks.
Abstract:
We describe the interaction design for a set of facilities that enable
users of an augmented version of the NCSA Mosaic browser to read,
write, and filter for annotations on arbitrary segments of World-Wide Web
documents, and share them with any other such user.
Keywords:
Mosaic, World-Wide Web, Group Annotation,
Collaborative Filtering, Seal of Approval.
Introduction
INTERFACE RENDERING
INTERACTION MODELS
Discourse Structures
Landmarks
Annotation Tour
User Profiles
Presence At A Virtual Place
CONCLUSION
References