In this paper, we explore flexible name resolution as a way of supporting extensibility for wide-area distributed services. Our approach, called Active Names, maps names to a chain of mobile programs that can customize how a service is located and how its results are transformed and transported back to the client. To illustrate the properties of our system, we implement prototypes of server selection based on end-to-end performance measurements, location-independent data transformation, and caching of composable active objects and demonstrate up to a five-fold performance improvement to end users. We show how these new services are developed, composed, and secured in our framework. Finally, we develop a set of algorithms to control how mobile Active Name programs are mapped onto available wide-area resources to optimize performance and availability.

Applying information retrieval techniques to the World Wide Web (WWW) environment is a unique challenge, mostly because of its hypertext/hypermedia nature and the richness of the meta-information it provides. We present four keyword-based search and ranking algorithms for locating relevant WWW pages with respect to user queries. The first algorithm, Boolean Spread Activation, extends the notion of word occurrence in Boolean retrieval model by propagating the occurrence of a query word in a page to other pages linked to it. The second algorithm, Most-cited, is based on the number of citing hyperlinks between potentially relevant WWW pages to increase the relevance scores of the referenced pages over the referencing pages. The third algorithm, TFxIDF or vector space model, is based on word distribution statistics. The last algorithm, Vector Spread Activation, combines vector space model and spread activation model. We conducted an experiment to evaluate the retrieval effectiveness of the...

Video-on-Demand systems have received a good deal of attention recently. Few studies, however, have addressed the problem of locating a video of interest in a large video database. This paper describes the design and implementation of a metadata database and query interface that attempts to solve this information retrieval problem. Sample queries were collected by interviewing a variety of users. These queries guided the design of indexes that can be used to answer the types of queries users want to ask. Three types of indexes were identified: 1) bibliographic (e.g., title, abstract,

The software and protocols associated with information browsing systems are largely designed with static access points and wired networks in mind, HTTP and the Web are a case in point. Static hosts are connected to wired, high bandwidth networks, and are capable of transmitting and receiving large amounts of data without significant delays. As such, the size and format of the data files being received by the browser/client has never been a concern. However, this causes problems when information access is desired on mobile hosts (MH), since data transmission over a wireless network is much slower than on a wired network. Mobile computers are also relatively resource-poor, compared to their desktop counterparts. This fact is ignored by HTTP servers, and large data files are transmitted to computers that cannot properly display them. Also, mobile computers operate in constantly changing network environments. It is possible for a mobile computer to become temporarily disconnected from a ne...

Introduction. 1.1. Information retrieval in the WWW. T he Internet and its associated WWW (World Wide Web) hypertext protocol have been experiencing an exponential growth during the past few years. Not only the number of users and Internet servers but also the amount of electronic information stored has been growing at an astounding pace. In spite of its popularity among publishers and users, the WWW doesn't seem to be entirely living up to expectations. With a growing number of pages and an increasing number of links, users are experiencing more and more difficulties in retrieving the information they require The retrieval of information from (electronic) databases and other information repositories has been the domain of the science of Information Retrieval (IR). Techniques and methods developed in IR have focused on indexing methods, automated retrieval by queries, query relevance improvement, database management, user inter

While digital libraries may simply be seen as replacing archival paper repositories, rapid organizational changes are associated with the movement to widespread on-line storage and manipulation of documents. Electronic publishing puts material rapidly into a wide open, relatively uncontrolled and unbounded medium. No intermediaries cause delays or limit dissemination. The reader enjoys on-line and often free access to recent writings. But with such disintermediation some valuable services are lost as well. We discuss those services, their current state, their value in an electronic world, and how they may be replaced in future information systems. Opportunities for new services will arise as well, and we cite some of them. The focus throughout will be on helping the customer who needs information. An important aspect of information is that it drives actionable decisions, i.e., decisions that in the end affect the state of the customer's business. 1. Introduction A Digital Library is p...

As the WWW grows at an increasing rate, efforts to make the technology more manageable are highly in demand. Applying advanced information retrieval techniques is one approach to such efforts. Despite the potential benefit of these techniques in reducing users information overload and improving the effectiveness access to on-line information, little research has been done on applying them to WWW environment. In this paper we present our attempt to apply the vector space retrieval model, relevance feedback mechanisms and a hypertext mapping technique as an integrated resource discovery system to the WWW. This paper discusses some design issues involved, as well as practical issues such as retrieval effectiveness, usability and scalability. Keywords: resource discovery, information retrieval, world wide web indexing, user interface 1 Introduction The explosive growth of the World Wide Web (WWW) [4] is making it difficult for a user to locate information that is relevant to his/her inte...

this paper we argue that prescient caching and smart scheduling are key techniques for overcoming the network bottleneck.

We consider a system with the infrastructure for the creation and interconnection of large numbers of distributed persistent objects. This system is exemplified by the Internet: potentially, every appliance and document on the Internet has both persistent state and the ability to interact with large numbers of other appliances and documents on the Internet. This paper elucidates the characteristics of such a system, and proposes the compositional requirements of its corresponding infrastructure. We explore the problems of specifying, composing, reasoning about, and implementing applications in such a system. A specific concern of our research is developing the infrastructure to support structuring distributed applications by using sequential, choice, and parallel composition, in the anarchic environment where application compositions may be unforeseeable, and interactions may be unknown prior to actually occurring. The structuring concepts discussed are relevant to a wide range of dist...

The World Wide Web has become a global distributed information system with a rapidly increasing user community. The advent of mobile computing coupled with the recent developments in wireless communications and personal computer technology, has created a new challenging area: mobile information access. Accessing web based information sources is likely to be one of the most important applications of mobile computers. However, the software and protocols associated with the WWW were designed with static hosts in mind. The resource limitations of mobile clients, low bandwidth of the wireless network and frequent disconnections are situations that existing WWW systems are ill equipped to deal with. There is a need to overcome these constraints and provide reliable information access from mobile computers. In this paper we present W 3 IQ, a system which supports mobile access to the web using asynchronous collaborative information retrieval techniques. We describe the model of W ...