We have built an HTTP based resource discovery system called Discover that provides a single point

Locating and accessing information in a large distributed system is a difficult problem of growing importance. This paper reports on our experience building and using a prototype system for transparent, user-guided associative access to the contents of a large, distributed set of WAIS servers. Our system is based on content routing, an architecture that makes use of content labels for locating and accessing information in large distributed systems [12]. Our content router for WAIS servers is implemented as a Semantic File System that constructs content labels from WAIS source and catalog files. The content router guides locating documents by suggesting terms that frequently appear with a given query term in document headlines. Sufficiently narrowed queries are routed to WAIS servers and processed in parallel. We have successfully used our content router to locate documents on a large number of WAIS servers. Along with demonstrating the feasibility of distributed finding in a large netw...

Information overload, arising from different types of heterogeneous digital data readily accessible from millions of repositories, is a critical problem on the Global Information Infrastructure (GII). We present an information brokering approach, architecture and techniques that address issues related to information overload on the GII. The approach spans three levels: representation (structure/format/type) of digital data, information content captured in the data; and the vocabulary underlying the data. Metadata (data/information about data) is used to abstract from heterogeneous representational details and capture information content. Domain specific ontologies are used to represent and interoperate across different vocabularies used to characterize information content. The approach thus suggested induces a metadata-based architecture that enables information brokering at the different levels. The feasibility of the approach is demonstrated by using a wide variety of metadata to capture information content for textual, image and structured data. These metadata belong to a wide spectrum and may range from metadata independent of the data content to those capturing information content in a application and domain specific

The rapid advances in computer and communication technologies, and their merger, is leading to a global information market place. It will consist of federations of very large number of information systems that will cooperate to varying extents to support the users ' information needs. We propose an architecture which may facilitate meeting these needs. It consists of three main components: information providers, information brokers and information consumers. We also propose an approach to information brokering. We discuss two of it's tasks: inf ormation resource discovery, which identi es relevant information sources for a given query, andquery processing, which involves the generation of appropriate mapping from relevant but structurally heterogeneous objects. Query processing consists of information f ocusing and information correlation. While the access-based search, and syntactic and hierarchical information organization has been adequate in the past, information brokering in presence of huge digital libraries or millions of information sources will likely require semantics and

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Dynamic synchronous Transfer Mode (DTM) is a new protocol suite based on synchronous fast circuit switching. The DTM network is based on bandwidth reservation and supports dynamic reallocation of bandwidth. It is designed to support real-time multimedia applications and high-speed computer communication. DTM uses a novel medium-access technique and provides a multicast connection-oriented service. In this paper, the connection establishment in the DTM network is discussed and a scheme for fast connection establishment is presented. The scheme allows for fast set-up of channels which results in an efficient usage of the network’s bandwidth and a short access delay for the user. Buffer handling and memory management implementations at a host interface supporting this scheme are also presented.

Effective accident management requires the organization of large amounts of information. This information consists of reference information which rarely changes during an accident and decision support information which changes very rapidly. Much of the rapidly changing information is a result of collaboration between accident response personnel. In this paper we discuss accident management systems as instances of cooperative information systems and describe three designs of an accident management system called FRIEND developed at Carnegie Mellon University. We concentrate on how each design handles the rapidly changing information with different notification mechanisms to support the collaboration between end users. We identify two specific types of architectures, distributed state and stateless, and conclude with a general discussion of architectures supporting cooperative information systems. 1 Introduction The wealth of information government service providers ...

We have defined a new network programming model called Mobile Assistant Programming (MAP) for development and

This thesis proposes a RepliCache that scaled well to a large size of objects. Combining caching and replication, RepliCache can amplifies advantages of both approaches. Web caching system avoids sending same documents repeatedly over Wide Area Network (WAN) by copying them at a closer location to users. Replication is a popular method for distributing server and network load in the Internet. An analysis of Web workload reveals that increasing fraction of the traffic volumes is associated with requests for large files. Large files such as audio and video data cause heavy traffic both in network bandwidth and data storage due to their large size. The existing Web caching servers, however generally store files no larger than tens of Mbytes to keep small and popular objects. Thus useful network bandwidth is mostly consumed by their unnecessary retransmission and their access latency is large. By storing large objects in a dedicated server and relaying through proxy cache, large objects c...