To improve the scalability of the Web it is common practice to apply caching and replication techniques. Numerous strategies for placing and maintaining multiple copies of Web documents at several sites have been proposed. These approaches essentially apply a global strategy by which a single family of protocols is used to choose replication sites and keep copies mutually consistent. We propose a more flexible approach by allowing each distributed document to have its own associated strategy. We propose a method for assigning an optimal strategy to each document separately and prove that it generates a family of optimal results. Using trace-based simulations, we show that optimal assignments clearly outperform any global strategy. We have designed an architecture for supporting documents that can dynamically select their optimal strategy, and evaluate its feasibility using a prototype

This paper introduces an approach to utilise open hypermedia structures such as links, annotations, collections and guided tours as meta data for Web resources. The paper introduces an XML based data format, called Open Hypermedia Interchange Format- OHIF, for such hypermedia structures. OHIF resembles XLink with respect to its representation of out-of-line links, but it goes beyond XLink with a more rich set of structuring mechanisms, including e.g. composites. Moreover OHIF includes an addressing mechanisms (LocSpecs) that goes beyond XPointer and URL in its ability to locate non-XML data segments. By means of the Webvise system, OHIF structures can be authored, imposed on Web pages, and finally linked on the Web as any ordinary Web resource. Following a link to an OHIF file automatically invokes a Webvise download of the meta data structures and the annotated Web content will be displayed in the browser. Moreover, the Webvise system provides support for users to create, manipulate, and share the OHIF structures together with custom made web pages and MS Office 2000 documents on WebDAV servers. These Webvise facilities goes beyond ealier open hypermedia systems in that it now allows fully distributed open hypermedia linking between Web pages and WebDAV aware desktop applications. The paper describes the OHIF format and demonstrates how the Webvise system handles OHIF. Finally, it argues for better support for handling user controlled meta data, e.g. support for linking in non-XML data, integration of external linking in the Web infrastructure, and collaboration support for external structures and meta-data.

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The World Wide Web has since its beginning provided linking to and from text documents encoded in HTML. The Web has evolved and most Web browsers now support a rich set of media types either by default or by the use of specialised content handlers, known as plug-ins. The limitations of the Web linking model are well known and they also extend into the realm of the other media types currently supported by Web browsers. This paper introduces the Mimicry system that allows authors and readers to link to and from temporal media (video and audio) on the Web. The system is integrated with the Arakne Environment, an open hypermedia integration aimed at Web augmentation.

. Experience from research on integrating versioning and configuration management support to the Web has shown that building such support on the basic Web infrastructure leads to undesirable architectural choices. This paper presents goals for a standardization effort called Delta-V which is extending the Web infrastructure, specifically the core network protocols HTTP and WebDAV, with capabilities for remote versioning and configuration management. Important goals include providing equal support for all content types, allowing versioning unaware applications to participate, supporting both mutable and immutable revisions, ensuring that human-readable strings are internationalizable, and provision of strong authentication and transport security. These goals are currently being used to develop the Delta-V protocol within the Internet Engineering Task Force. 1 Introduction What if you were an employee of a small design firm called DesignHaus, working on a Web site update for...

OpenCM is a new configuration management system created to support high-assurance development in open-source projects. Because OpenCM is designed as an open source tool, robust replication support is essential, and security requirements are somewhat unusual – preservation of access is as important as prevention. Also, integrity preservation is a primary focus of the information architecture. Because some of our supported development activities target high-assurance systems, traceability and recovery from compromise are also vital concerns. This paper describes the mechanisms used by OpenCM to meet these needs. While some of the techniques used are particular to archival stores, others have potentially broader applications in replication-based distributed systems. 1

this paper we consider a Web application (or simply an application), as a Versus client with the ability of executing a task through parallel data processing. Therefore each application should be composed by a group of independent threads

Search engines provide search results based on a large repository of pages downloaded by a web crawler from several servers. To provide best results, this repository must be kept as fresh as possible, but this can be difficult due to the large volume of pages involved and to the fact that polling is the only method for detecting changes. In this paper, we explore and compare several alternatives for keeping fresh repositories that involve some degree of cooperation from servers. 1.

This paper analyses transformations in collaborative activities that a computersupported collaborative writing system introduces into co-authors' practices, and, discusses implications for the design of collaborative tools for writing. The analysis is grounded in user studies of four different groups of co-authors writing an academic report during two different collaborative situations. Two groups collaborate face-to-face using a word processor and the other two groups collaborate at a distance using a synchronous collaborative writing system.

YouServ is a system that allows its users to pool existing desktop computing resources for high availability web hosting and file sharing. By exploiting standard web and internet protocols (e.g. HTTP and DNS), YouServ does not require those who access YouServ-published content to install special purpose software. Because it requires minimal server-side resources and administration, YouServ can be provided at a very low cost. We describe the design, implementation, and a successful intranet deployment of the YouServ system, and compare it with several alternatives.