A Scalable Middleware Solution for Advanced Wide Area Web Services

To alleviate scalability problems in the Web, many researchers concentrate on how to incorporate advanced caching and replication techniques. Many solutions incorporate object-based techniques. In particular, Web resources are considered as distributed objects offering a well-defined interface. We argue that most proposals ignore two important aspects. First, there is little discussion on what kind of coherence should be provided. Proposing specific caching or replication solutions makes sense only if we know what coherence model they should implement. Second, most proposals treat all Web resources alike. Such a one-size-fits-all approach will never work in a wide-area system. We propose a solution in which Web resources are encapsulated in physically distributed shared objects. Each object should encapsulate not only state and operations, but also the policy by which its state is distributed, cached, replicated, migrated, etc

Enveloping Sophisticated Tools into Process-Centered Environments

We present a tool integration strategy based on enveloping pre-existing tools without source code modifications or recompilation, and without assuming an extension language, application programming interface, or any other special capabilities on the part of the tool. This Black Box enveloping (or wrapping) idea has existed for a long time, but was previously restricted to relatively simple tools. We describe the design and implementation of, and experimentation with, a new Black Box enveloping facility intended for sophisticated tools --- with particular concern for the emerging class of groupware applications

Reviewing two Multimedia Presentation (quasi-) Standards

In this paper, we compare the BERKOM globally ac cessible services project (GLASS) with the well-known World-Wide Web with respect to the ease of development, realization, and distribution of multimedia presentations. This comparison is based on the experiences we gained when implementing a gateway between GLASS and the World-Wide Web. Since both systems are shown to have obvious weaknesses, we are concluding this paper with a presentation of a better way to multimedia document en gineering and distribution. This concept is based on a well-accepted approach to function-shipping in the Inter net: the Java language, permitting for example a smooth integration of GLASSµ MHEG objects and WWW HTML pages within one common environment

Towards a Modification Exchange Language for Distributed RDF Repositories

Many RDF repositories have already been implemented with various access languages and mechanisms. The aim of the EDUTELLA framework is to allow communication between different RDF repository implementations. Part of EDUTELLA is a Query Exchange Language (QEL) which can be used as lingua franca to retrieve information from RDF repositories. This work shows why we also need standardization of distributed modification capabilities. We describe use case scenarios for annotation and replication services and use them as guideline for our approach towards a Modification Exchange Language (MEL) for distributed RDF repositories

Quantifying the Overall Impact of Caching and Replication in the Web

This paper discusses the benefits and drawbacks of caching and replication strategies in the WWW with respect to the Internet infrastructure. Bandwidth consumption, latency, and overall error rates are considered to be most important from a network point of view. The dependencies of these values with input parameters like degree of replication, document popularity, actual cache hit rates, and error rates are highlighted. In order to determine the influence of different caching and replication strategies on the behavior of a single proxy server with respect to these values, trace-based simulations are used. Since the overall effects of such strate- gies can hardly be decided with this approach alone, a mathematical model has been developed to deal with their influence on the network as a whole. Together, this two-tiered approach permits us to propose quantita- tive assessments on the influence different caching and replication proposals (are going to) have on the Inter- net infrastructure

Quantifying the Overall Impact of Caching and Replication in the Web

This paper discusses the benefits and drawbacks of caching and replication strategies in the WWW with respect to the Internet infrastructure. Bandwidth consumption, latency, and overall error rates are considered to be most important from a network point of view. The dependencies of these values with input parameters like degree of replication, document popularity, actual cache hit rates, and error rates are highlighted. In order to determine the influence of different caching and replication strategies on the behavior of a single proxy server with respect to these values, trace-based simulations are used. Since the overall effects of such strategies can hardly be decided with this approach alone, a mathematical model has been developed to deal with their influence on the network as a whole. Together, this two-tiered approach permits us to propose quantitative assessments on the influence different caching and replication proposals (are going to) have on the Internet infrastructure