Re: [ohs-dev] USE CASES: Text Views with PDAs

From: Malcolm Dean (
Date: Sun Aug 20 2000 - 15:40:57 PDT

Please ignore the first message regarding the Agenda PDA. It is incomplete and was sent inadvertently.

The Agenda is just one of several handhelds now arriving which run a complete Linux and have an X GUI, and can even be implemented as servers. Development kits are very similar to those commonly in use, and run on any PC.

Since the units will be priced starting at only $150, it's clear that the days of tiny, dumb, WAP-like devices are quickly ending. It might therefore be better to understand the implications of this new class of device, rather than aim at a level of technology which will soon be outmoded.

Malcolm Dean

  ----- Original Message -----
  From: Malcolm Dean
  Sent: Friday, August 18, 2000 5:39 PM
  Subject: Re: [ohs-dev] USE CASES: Power Browsing, Outline Link Navigation for Focused Web Searching, and Text Views with PDAs

  I respond with some hesitation, as what is appropriate here remains something of an unrevealed mystery to the uninitiated. Nevertheless, concerns regarding handheld devices should take into account the next generation, just now approaching release as the Agenda VR PDA.

  Malcolm Dean
  News Editor, XML Journal (Visit
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    ----- Original Message -----
    From: John J. Deneen
    Sent: Friday, August 18, 2000 5:05 PM
    Subject: [ohs-dev] USE CASES: Power Browsing, Outline Link Navigation for Focused Web Searching, and Text Views with PDAs

    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."

      a.. 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."
      a.. 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 space."
      a.. 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."
      a.. 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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