Harald Weinreich

Web page revisitation revisited: implications of a long-term click-stream study of browser usage

This paper presents results of an extensive long-term click-stream study of Web browser usage. Focusing on character and challenges of page revisitation, previous findings from seven to thirteen years ago are updated. The term page re-visit had to be differentiated, since the recurrence rate--the key measure for the share of page revisits--turns out to strongly depend on interpretation. We identify different types of revisitation that allow assessing the quality of current user support and developing concepts for new tools. Individual navigation strategies differ dramatically and are strongly influenced by personal habits and type of site visited. Based on user action logs and interviews, we distinguished short-term revisits (backtrack or undo) from medium-term (re-utilize or observe) and long-term revisits (rediscover). We analyze current problems and provide suggestions for improving support for different revisitation types.

Not quite the average: An empirical study of Web use

In the past decade, the World Wide Web has been subject to dramatic changes. Web sites have evolved from static information resources to dynamic and interactive applications that are used for a broad scope of activities on a daily basis. To examine the consequences of these changes on user behavior, we conducted a long-term client-side Web usage study with twenty-five participants. This report presents results of this study and compares the user behavior with previous long-term browser usage studies, which range in age from seven to thirteen years. Based on the empirical data and the interview results, various implications for the interface design of browsers and Web sites are discussed. A major finding is the decreasing prominence of backtracking in Web navigation. This can largely be attributed to the increasing importance of dynamic, service-oriented Web sites. Users do not navigate on these sites searching for information, but rather interact with an online application to complete certain tasks. Furthermore, the usage of multiple windows and tabs has partly replaced back button usage, posing new challenges for user orientation and backtracking. We found that Web browsing is a rapid activity even for pages with substantial content, which calls for page designs that allow for cursory reading. Click maps provide additional information on how users interact with the Web on page level. Finally, substantial differences were observed between users, and characteristic usage patterns for different types of Web sites emphasize the need for more adaptive and customizable Web browsers.

Electronic contracting with COSMOS-how to establish, negotiate and execute electronic contracts on the Internet

Today, the Internet gains more and more attraction even for small companies to contact business partners and to automate cooperation between each other. However, the smaller the company the higher the relative setup costs that are required if the complete process of a commercial transaction is to be supported. We propose COSMOS as an Internet-based electronic contracting service that facilitates commercial partners with offer catalogues, a brokerage service, contract negotiation and signing as well as contract execution. The COSMOS architecture supports these functions in an integrated, unified way. The design and execution of contracts integrates patterns from the CORBA Joint Business Object Facility.

The look of the link - concepts for the user interface of extended hyperlinks

The design of hypertext systems has been subject to intense research. Apparently, one topic was mostly neglected: how to visualize and interact with link markers. This paper presents an overview of pragmatic historical approaches, and discusses problems evolving from sophisticated hypertext linking features. Blending the potential of an XLink-enhanced Web with old ideas and recent GUI techniques, a vision for browser link interfaces of the future is being developed. We hope to stimulate the development of a standard for hyperlink marker interfaces, which is easy-to-use, feasible for extended linking features, and more consistent than current approaches.

Concepts for improved visualization of Web link attributes

Abstract This paper discusses methods to generate and display automatically additional hyperlink information to the users of the World Wide Web. Current Web browsers make it hard to predict what will happen if a link is followed: users get different information than they expect, a new window may be opened, a download starts, or the destination object is just not available. Instead of giving an appropriate notification in advance, users have to follow a link, check whether the document contains the expected information, get back, try another link etc. However, usually it is possible to obtain additional hyperlink information from several sources like link anchor tags, the user’s history and Web servers. Furthermore, with little enhancements, Web servers may include even more additional information to the hyperlinks in Web documents. These can be displayed before users select a link to improve navigation and reduce the cognitive overhead. In this paper several types of Web hyperlink information are listed, potential methods to present these facts are compared, the prototype implementation of the proposed concept — called by us HyperScout — is presented, and further developments are discussed.

SUPPORTING ELECTRONIC COMMERCE TRANSACTIONS WITH CONTRACTING SERVICES

Based on the specific characteristics and requirements for an adequate electronic commerce system support, this article gives an overview of the respective distributed systems technologies which are available for open and heterogeneous electronic commerce applications. Abstracting from basic communication mechanisms such as (transactionally secure) remote procedure calls and remote database access mechanisms, this includes service trading and brokerage functions as well as security aspects including such as notary and non-repudiation functions. Further important elements of a system infrastructure for electronic commerce applications are: Common middleware infrastructures, componentware techniques, distributed and mobile agent technologies etc. As electronic transactions enter the phase of performance, increasingly new and important functions are required. Among these are: Negotiation protocols to support both the settlement and fulfillment of electronic contracts as well as ad-hoc workflow management support for compound and distributed services in electronic commerce applications. In addition to an overview of the state of the art of the respective technology, the article briefly presents some related projects conducted by the authors jointly with international partners in order to realize some of the important new functions of a system infrastructure for open distributed electronic commerce applications.

Advanced concepts for next generation portals

Over the last two years, portal sites surfaced as a major trend in electronic commerce. Unlike many other exaggerated trends, portals have become an important facet of the World Wide Web which is likely to stay. Emerging from search engines and catalogues, they integrate an increasing amount of information and functionality. The paper reflects on portal characteristics as well as on foundations of their realization and introduces technology needed for the next generation service trading concepts: based on the promising open source project Jetspeed, a prototype of the GIBRALTAR service portal is introduced, capable of integrating, trading and composing complex remote e-services.

Automatic support for web user studies with SCONE and TEA

This paper describes the concepts of TEA, a flexible tool that supports user tests by automating repetitive tasks and collecting data of user inputs and actions. TEA was specifically designed for user studies in the World Wide Web and is able to interact with a web browser. Building on a web intermediary (WBI) and a framework for web enhancement tools (SCONE), TEA can be applied in a range of test settings - providing either a controlled laboratory environment or a quick tool for collecting informal data.

Comparing link marker visualization techniques: changes in reading behavior

Links are one of the most important means for navigation in the World Wide Web. However, the visualization of and the interaction with Web links have been scarcely explored, although Links have severe implications on the appearance and usability of Web pages and the World Wide Web as such.This paper presents two studies giving first insights of the effects of link visualization techniques on reading habits and performance. The first user study compares different highlighting techniques for link markers and evaluates their effect on reading performance and user acceptance. The second study examines links-on-demand, links that appear when pressing a dedicated key, and discusses their possible effects on reading and browsing habits.The findings of the conducted studies imply that the standard appearance of link markers has seriously underestimated effects on the usability of Web pages. They can significantly reduce the readability of the text, and alternatives should be carefully considered for the design of future Web browsers.

Scone: Ein Framework zur evaluativen Realisierung von Erweiterungen des Webs

Projekte, die sich mit der Entwicklung und Evaluation von Konzepten, Techniken und Werkzeugen zur Verbesserung der Benutzbarkeit des Webs befassen, stehen oft vor dem Problem, dass die Implementation entsprechender Prototypen sehr aufwendig ist. Es stand bisher kein angemessenes Framework zur Verfugung, das solche Entwicklungen vereinfachen konnte. Dieses Paper stellt das Framework „Scone“ vor, das die prototypische Entwicklung und Evaluation von unterschiedlichen Arten von Web-Erweiterungen—insbesondere solcher zur Navigation und Orientierung im Web—erleichtert. Das Framework bietet eine Reihe von Komponenten, welche es u.a. erlauben, die Darstellung der Dokumente im Browser zu andern, auf Benutzeraktionen mit dem Browser zu reagieren, den Browser zu steuern und auch selbsttatig Informationen aus dem Netz zu sammeln. Zusatzlich wird die Evaluation solcher Systeme durch Benutzbarkeitsstudien unterstutzt.