The explosive growth of the Internet and the proliferation of smart cellular phones and handheld wireless devices is widening an already large gap between Internet clients. Clients vary in their hardware resources, software sophistication, and quality of connectivity, yet server support for client variation ranges from relatively poor to none at all. In this paper we introduce some design principles that we believe are fundamental to providing “meaningful” Internet access for the entire range of clients. In particular, we show how to perform on-demand datatype-specific lossy compression on semantically typed data, tailoring content to the specific constraints of the client. We instantiate our design principles in a proxy architecture that further exploits typed data to enable application-level management of scarce network resources. Our proxy architecture generalizes previous work addressing all three aspects of client variation by applying well-understood techniques in a novel way, resulting in quantitatively better end-to-end performance, higher quality display output, and new capabilities for lowend clients. 1

Content delivery over the Internet needs to address both the multimedia nature of the content and the capabilities of the diverse client platforms the content is being delivered to. We present a system that adapts multimedia Web documents to optimally match the capabilities of the client device requesting it. This system has two key components: (1) A representation scheme called the InfoPyramid that provides a multi-modal, multi-resolution representation hierarchy for multimedia. (2) A customizer that selects the best content representation to meet the client capabilities while delivering the most value. We model the selection process as a resource allocation problem in a generalized rate-distortion framework. In this framework, we address the issue of both multiple media types in a Web document and multiple resource types at the client. We extend this framework to allow prioritization on the content items in a Web document. We illustrate our content adaptation technique with a web ...

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. Keywords Web; Browser; PDA (Personal Digital Assistant); PalmPilot; Wireless; HTTP; Proxy; Baby faces. INTRODUCTION Mobile access to information is a key to individual productivity. Small handheld computers are becoming more crucial in our daily lives. A handheld devi...

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Digestor is a software system which automatically re-authors arbitrary documents from the World-Wide Web to display appropriately on small screen devices such as PDAs and cellular phones, providing device-independent access to the Web. Digestor is implemented as an HTTP proxy which dynamically re-authors requested Web pages using a heuristic planning algorithm and a set of structural page transformations to achieve the best looking document for a given display size. 1. Introduction Access to World-Wide Web documents from personal electronic devices has been demonstrated in research projects [2,10,17,18], and is now becoming a commercial reality. General Magic's Presto!Links for Sony's MagicLink, AllPen's NetHopper for the Newton and Sharp's MI-10 (Figure 1, shown at right), all provide WWW browsers for PDA class devices, while the Nokia 9000 Communicator and Samsung's Duett provide Web access capabilities from cellular phones. Figure 1. Digestor: Device-Independent Access to the W...

When a machine is connected to the Internet via a slow network, such as a 28.8 Kbps modem, the cumulative latency to communicate over the Internet to World Wide Web servers and then transfer documents over the slow network can be significant. We have built a system that optimistically transfers data that may be out of date, then sends either a subsequent confirmation that the data is current or a delta to change the older version to the current one. In addition, if both sides of the slow link already store the same older version, just the delta need be transferred to update it. Our mechanism is optimistic because it assumes that much of the time there will be sufficient idle time to transfer most or all of the older version before the newer version is available, and because it assumes that the changes between the two versions will be small relative to the actual document. Timings of retrievals of random URLs in the Internet support the former assumption, while experiments using a versi...

Web content hosting, in which a Web server stores and provides Web access to documents for different customers, is becoming increasingly common. Due to the variety of customers (corporate, individuals, etc.), providing differentiated levels of service is often an important issue for the hosts. Most server implementations, however, are not structured to service requests based on different levels of quality of service (QoS). This paper presents our attempts at augmenting a popular server implementation with differentiated QoS features. We explore priority-based request scheduling at both user and kernel levels. We find that simple strategies such as controlling the numbers of processes can improve the response time of high-priority requests notably while preserving the system throughput. We also find that the kernellevel approach tends to penalize low-priority requests less significantly than the user-level approach, while improving the performance of high-priority requests similarly. Ba...

We demonstrate a new browsing technique for devices with small displays such as PDAs or cellular phones. We concentrate on end-game browsing, where the user is close to or on the target page. We make browsing more efficient and easier by Accordion Summarization. In this technique the Web page is first represented as a short summary. The user can then drill down to discover relevant parts of the page. If desired, keywords can be highlighted and exposed automatically. We discuss our techniques, architecture, interface facilities, and the result of user evaluations. We measured a 57 % improvement in browsing speed and 75% reduction in input effort.

In this paper, we present a proxy based system (MOWSER) to support web browsing from mobile clients over wireless networks. Mowser is a proxy agent between the mobile host and the web server, which performs active transcoding of data on both upstream and downstream traffic to present web information to the mobile user according to the QoS parameters set by the user. Active transcoding is defined as modifying the HTTP stream in situ, and it is entirely transparent to the user. Further, our system does not pose any additional requirements on the mobile user. This is an improvement over other proxy based systems, which only transcode images on the downstream and are mostly not configurable. While developed for mobile users, such a system can actually be useful in any low bandwidth scenario.

We propose a new approach to programming web applications that increases the web's computational power, the web's flexibility, and web programmer productivity. Whereas web servers have traditionally been responsible for producing all content, intermediaries now provide new places for producing and manipulating web data. We define intermediaries as computational elements that lie along the path of a web transaction. In this paper, we describe the fundamental ideas behind intermediaries and provide a collection of example applications. We also describe WBI, an implemented architecture for building intermediaries that we have used to construct many applications, including personal histories, password management, image distillation, collaborative filtering, targeted advertising, and web advising.