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Content Repurposing for Small Devices - INTRODUCTION, BACKGROUND, METHODS OF CONTENT REPURPOSING, Repurposing Strategies, Redrawing the Display, FUTURE WORK, CONCLUSION

information user server links

Neil C. Rowe
U.S. Naval Postgraduate School, USA

INTRODUCTION

Content repurposing is the reorganizing of data for presentation on different display hardware (Singh, 2004). It has been particularly important recently with the growth of handheld devices such as personal digital assistants (PDAs), sophisticated telephones, and other small specialized devices. Unfortunately, such devices pose serious problems for multimedia delivery. With their tiny screens (150 by 150 for a basic Palm PDA or 240 by 320 for a more modern one, vs. 640 by 480 for standard computer screens), one cannot display much information (i.e., most of a Web page); with their low bandwidths, one cannot display video and audio transmissions from a server (i.e., streaming) with much quality; and with their small storage capabilities, large media files cannot be stored for later playback. Furthermore, new devices and old ones with new characteristics have been appearing at a high rate, so software vendors are having difficulty keeping pace. So some real-time, systematic, and automated planning could be helpful in figuring how to show desired data, especially multimedia, on a broad range of devices.

BACKGROUND

The World Wide Web is the de facto standard for providing easily accessible information to people. So it is desirable to use it and its language—HTML—as a basis for display for small handheld devices. This would enable people to look up ratings of products while shopping, check routes while driving, and perform knowledge-intensive jobs while walking. HTML is, in fact, device-independent. It requires the display device and its Web-browser software to make decisions about how to display its information within guidelines. But HTML does not provide enough information to devices to ensure much user-friendliness of the resulting display: It does not tell the browser where to break lines or which graphics to keep collocated. Display problems are exacerbated when screen sizes, screen shapes, audio capabilities, or video capabilities are significantly different. Microbrowser markup languages like WML, S-HTML, and HDML, which are based on HTML but designed to better serve the needs of small devices, help, but these only solve some of the problems.

Content repurposing is a general term for reformatting information for different displays. It occurs frequently with content management for an organization’s publications (Boiko, 2002), where content or information is broken into pieces and entered in a repository to be used for different publications. However, a repository is not cost-effective unless the information is reused many times, something not generally true for Web pages. Content repurposing for small devices also involves real-time decisions about priorities. For these reasons, the repository approach often is not used with small devices.

Content repurposing can be done either before or after a request for it. Preprocessing can create separate pages for different devices, and the device fetches the page appropriate to it. It also can involve conditional statements in pages that cause different code to be executed for different devices; such statements can be done with code in JavaScript, PHP embedded within HTML, or more complex server codes using such facilities as Java Server Pages (JSP) and Active Server Pages (ASP). It also can involve device-specific planning (Karadkar, 2004). Many popular Web sites provide preprocessed pages for different kinds of devices. Preprocessing is cost-effective for frequently needed content but requires setup time and can require considerable storage space, if there is a large amount of content and ways to display it.

Content repurposing also can be either client-side or server-side. Server-side means a server supplies repurposed information for the client device; client-side means the device itself decides what to display and how. Server-side repurposing saves work for the device, which is important for primitive devices, and can adjust to fluctuations in network bandwidth (Lyu et al., 2003) but requires added complexity in the server and significant time delays in getting information to the server. Devices can have designated proxy servers for their needs. Client-side repurposing, on the other hand, can respond quickly to changing user needs. Its disadvantages are the additional processing burden on an already-slow device and higher bandwidth demands, since information is not eliminated until after it reaches the device. The limitations of small devices require most audio and video repurposing to be server-side.

METHODS OF CONTENT REPURPOSING

Repurposing Strategies

Content repurposing for small devices can be accomplished by several methods, including panning, zooming, reformatting, substitution of links, and modification of content.

A default repurposing method of Internet Explorer and Netscape browser software is to show a window on the full display when it is too large to fit on the device screen. Then the user can manipulate slider bars on the bottom and side of the window to view all the content (pan over it). Some systems break content into overlapping tiles (Kasik, 2004), precomputed units of display information, and users can pan only from tile to tile; this can prevent splitting of key features like buttons and simplifies client-side processing, but it only works for certain kinds of content. Panning may be unsatisfactory for large displays like maps, since considerable screen manipulation may be required, and good understanding may require an overview. But it works fine for most content.

Another idea is to change the scale of view, zooming in (closer) or out (further). This can be either automatic or user-controlled. The MapQuest city-map utility (www.mapquest.com) provides user-controlled zooming by dynamically creating maps at several levels of detail, so the user can start with a city and progressively narrow on a neighborhood (as well as do panning). A problem for zooming out is that some details like text and thin lines cannot be shrunk beyond a certain minimum size and still remain legible. Such details may be optional; for instance, MapQuest omits most street names and many of the streets in its broadest view. But this may not be what the user wants. Different details can be shrunk at different rates, so that lines one pixel wide are not shrunk at all (Ma & Singh, 2003), but this requires content-specific tailoring.

The formatting of the page can be modified to use equivalent constructs that display better on a destination device (Government of Canada, 2004). For instance, with HTML, the fonts can be made smaller or narrower (taking into account viewability on the device) by font tags, line spacing can be reduced, or blank space can be eliminated. Since tables take extra space, they can be converted into text. Small images or video can substitute for large images or video, when their content permits. Text can be presented sequentially in the same box in the screen to save display space (Wobbrock et al., 2002). For audio and video, the sampling or frame rate can be decreased (one image per second is fine for many applications, provided the rate is steady). Visual clues can be added to the display to indicate items just offscreen (Baudisch & Rosenholtz, 2003).

Clickable links can point to blocks of less important information, thereby reducing the amount of content to be displayed at once. This is especially good for media objects, which can require both bandwidth and screen size, but also helps for paragraphs of details. Links can be thumbnail images, which is helpful for pages familiar to the user. Links also can point to pages containing additional links so the scheme can be hierarchical. In fact, Buyukkoten et al. (2002) experimented with repurposing displays containing links exclusively. But insertion of links requires rating the content of the page by importance, a difficult problem in general (as discussed later), to decide what content is converted into links. It also requires a careful wording of text links since just something like “picture here” is not helpful, but a too-long link may be worse than no link at all. Complex link hierarchies also may cause users to get lost.

One also can modify the content of a display by just eliminating unimportant or useless detail and rearranging the display (Gupta et al., 2003). For instance, advertisements, acknowledgements, and horizontal bars can be removed, as well as JavaScript code and Macromedia Flash (SWF) images, since most are only decorative. Removed content need not be contiguous, as with removal of a power subsystem from a system diagram. In addition, forms and tables can lose their associated graphics. The lines in block diagrams often can be shortened when their lengths do not matter. Color images can be converted to black and white, although one must be careful to maintain feature visibility, perhaps by exaggerating the contrast. User assistance in deciding what to eliminate or summarize is helpful as user judgment provides insights that cannot easily be automated, as with selection of highlights for video (Pea et al., 2004). An important special application is selection of information from a page for each user in a set of users (Han, Perret, & Naghshineh, 2000). Appropriate modification of the display for a mobile device also can be quite radical; for instance, a good way to support route-following on a small device could be to give spoken directions rather than a map (Kray et al., 2003).

Redrawing the Display

Many of methods discussed require changing the layout of a page of information. Thus, content repurposing needs to use methods of efficient and user-friendly display formatting (Kamada & Kawai, 1991; Tan, Ong, & Wong, 1993). This can be a difficult constraint optimization problem where the primary constraints are those of keeping related information together as much as possible in the display. Examples of what needs to be kept together are section headings with their subsequent paragraphs, links with their describing paragraphs, images with their captions, and images with their text references. Some of the necessary constraints, including device-specific ones, can be learned from observing users (Anderson, Domingos, & Weld, 2001). Even with good page design, content search tools are helpful with large displays like maps to enable users to find things quickly without needing to pan or zoom.

FUTURE WORK

Content repurposing is currently an active area of research, and we are likely to see a number of innovations in the near future in both academia and industry. The large number of competing approaches will dwindle as concensus standards are reached for some of the technology, much as de facto standards have emerged in Web-page style. It is likely that manufacturers of small devices will provide increasingly sophisticated repurposing in their software to reduce the burden on servers. XML increasingly will be used to support repurposing, as it has achieved widespread acceptance in a short time for many other applications. XML will be used to provide standard descriptors for information objects within organizations. But XML will not solve all problems, and the issue of incompatible XML taxonomies could impede progress.

CONCLUSION

Content repurposing recently has become a key issue in management of small wireless devices as people want to display the information they can display on traditional screens and have discovered that it often looks bad on a small device. So strategies are being devised to modify display information for these devices. Simple strategies are effective for some content, but there are many special cases of information that require more sophisticated methods due to their size or organization.

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