[ohs-dev] USE CASES: Power Browsing, Outline Link Navigation for Focused Web Searching, and Text Views with PDAs

From: John J. Deneen (jjdeneen@ricochet.net)
Date: Fri Aug 18 2000 - 17:05:05 PDT

With the volume of Internet traffic doubling every 100 days and with
that traffic rapidly migrating from PCs to wireless devices like cell
phones and hand-held computers, the OHS capabilities is an important
enabling technology and visa versa as shown below.


Abstract: We have designed and implemented new Web browsing facilities
to support effective navigation on Personal Digital Assistants (PDAs)
with limited capabilities: low bandwidth, small display, and slow CPU.
The implementation supports wireless browsing from 3Com’s Palm Pilot. An
HTTP proxy fetches web pages on the client’s behalf and dynamically
generates summary views to be transmitted to the client. These summaries
represent both the link structure and contents of a set of web pages,
using information about link importance. We discuss the architecture,
user interface facilities, and the results of comparative performance
evaluations. We measured a 45% gain in browsing speed, and a 42%
reduction in required pen movements.

... "Our technique takes advantage of the implicit structure of web
pages. Web pages consist of text and multimedia elements, along with
embedded links containing URLs for linked pages or files. During the
user's final approach navigation phase, our Power Browser displays
consists of a set of “link descriptions” which we generate heuristically
from anchor text, URL structure, or ALT tags, as appropriate to the
link. This structure includes not only the links on a single page, but a
hierarchical structure of links
on linked pages as well. The user can directly retrieve a page from any
link description visible on the screen.

The Power Browser’s tree arrangement of links displays both the user’s
location and the neighboring navigation environment at all times. One
positive consequence is that users can jump to a sibling page with a
single action. (Siblings are pages that are pointed to by the same
parent page). In conventional browsing, the user has to backtrack and
move forward again to reach siblings."

   * Gestures - "The tree control used for displaying the link structure
     (Figure 3) is operated using gestures. A node is expanded with a
     left-to-right gesture over the link to be expanded, and collapsed
     with a right-to-left gesture. Up-down and down-up gestures operate
     scrolling. The text of a node’s associated page is displayed by a
     single pen-tap on the link description."

   * Link Redundancy Reduction - "Another method for navigation support
     is hiding; restricting the navigation space by hiding links to
     pages. Most web sites have many duplicate links within their link
     structure. For instance, some pages provide a navigation bar
     support that gives direct access to the most critical web pages
     within the site. This structure is often repeated on each page.
     Also, many pages provide a link to their parent page or all the way
     back to the root page of the site. There can be duplicate links
     within the same page as well. Some pages provide alternative
     options for the same links (e.g., a page accessible through both
     the anchor and an image). The proxy server removes any duplicate
     links that it finds. This assures that each link on the tree
     control is unique. If the same link has multiple descriptions, a
     heuristic is used to choose the best one. Link descriptions are
     preferred to alternative text. If there are multiple link
     descriptions, the longest one is chosen. When we tested the browser
     with duplicate removal, we observed that navigation became easier
     since it reduced the cognitive load for the user to recognize
     duplicate links. Restricting the navigation space compacted the
     link structure and reduced the complexity of the unrestricted

   * Link Ordering - "One of the enhancements of the system compared to
     a traditional browser is the option of ordering the links. A
     standard browser displays the links in the sequence they appear in
     the document. Since only a small number of links can be displayed
     at a time on the PDA, it becomes important to display them in an
     efficient order. The Power Browser allows users to specify three
     sorting schemes: original, alphabetical, and page ranked. For
     instance if we are looking for a person’s first name among a large
     list that is ordered by last name, we would prefer to have the
     names re-ordered alphabetically according to their first name. This
     feature was used in our previous example to get the group members
     ordered alphabetically according to first name."

   * More info with use case illustrations


Link Navigation : The first contribution is that the system provides
facilities for navigating without having to view full pages. The
navigation and viewing phases are therefore shown separately in Figure
1c. This separation is important because the transmission and
examination of pages is so expensive. It is therefore wasteful to view
content simply to find that one needs to navigate on to the next page.

We this separation by extracting informative link information from
pages. Instead of displaying each page the user requests during the
navigation phase, we first show a page summary that presents the links
contained on the page. The links are arranged in a tree widget, similar
to file folders in a file browser. Users navigate by expanding and
contracting nodes. This approach frequently allows users to recognize
the page they need to move to next on their way to a final destination.
Once they are reasonably confident that they have found the desired
page, they switch from the link view to a text view. The text view shows
as much as possible of the actual page text.

Figure 2 shows example screen shots. Figure 2a is a link view of the
Stanford Database Group. Each left justified entry is the description of
a link on that root page. The Members link has been expanded to show the
links on the Members sub-page. The link to Arturo Crespo's home page has
been further expanded. Figure 2b is a text view, showing salient
information on Arturo's page. Figure 2c finally, provides an overview of
the navigation levels. This is useful when operating at deep nesting
levels. The details of the Power Browser's navigation facilities are
documented in [8].

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