For the past few years, WWW (World Wide Web) traffic has been tremendously growing on the Internet. However, it ironically becomes ¡§World Wide Wait¡¨ due to overloaded server and/or seriously congested network. Almost any computer system that suffers from latency or bandwidth problems can benefit from caching. The introduction of cache concept to WWW server certainly reduce the waiting time at clients by efficiently relieving both the server and network load. The purpose of this thesis is to design a hierarchical cache system so that it can work efficiently. The cache servers being used today have encountered the problems of lack of efficient collaboration due to different configuration flavors of management. In other words, the highest level of a hierarchical cache system may easily become the bottleneck, which in turn slow down the entire cache system. In our cache design, we apply inclusive and exclusive relationship to modify the ICP (Internet Cache Protocol) and use the recursive concept to build a hierarchical architecture to avoid the un-necessary information query. This implies that the lowest level can fetch the data from the destination server directly and perform the update recursively to its upper level. The up-side-down traffic flow, reffered to as reverse traffic flow in this thesis, can substantially release the load of upper levels in the hierarchy. For the purpose of performance evaluation, we derive a general mathematical equation by analyzing the operation procedures step by step. The analytical results have shown that the highest level within this hierarchy can reduce almost 50% of the load under the worst-case assumption. Although the lower levels may slightly increase their work load, it does significantly increase the overall WWW efficiency and avoid the potential bottlenecks by balancing the loads among different levels.

WWW-Vortrag UNIX-Stammtisch 06/95.

Was ist XML? Was kann man damit machen? Welche Anwendungsgebiete für XML sind denkbar? Was gibt es derzeit für Applikationen? Wie wirkt sich diese neue (Meta-)Sprache auf die zukünftige Netznutzung aus?

In this part of the thesis we have investigated how the navigation utilizing web recommendations can be implemented on the e-commerce websites based on integrated data sources. The integrated e-commerce websites are an interesting use case for web recommendations. One of the reasons for this interest is that many modern, large and economically successful e-commerce websites follow the integrated approach. Another reason is that especially in the integrated environment, due to the lack of the pre-defined semantic connections between the data, the web recommendations step forward as means of enabling user navigation. In this chapter we have presented the architecture for the websites based on integrated data sources named EC-Fuice. We have also presented the prototypical implementation of our architecture which serves as a proof-of-concept and investigated the challenges of creating navigation on an integrated website. The following issues were addressed in this part of the thesis:  Combination of several state-of-the-art tools and techniques in the fields of databases, data integration, ontology matching and web engineering into one generic architecture for creating integrated websites.  Comparative experiments with several techniques for instance matching (also known as record linkage or duplicate detection). Investigation on using the ontology matching to facilitate the instance matching.  Comparative experiments with several techniques for ontology matching. Investigations on the instance-based ontology matching and the possibilities for combining instance-based ontology matching with other techniques for ontology matching.  Investigation of the possibilities to improve user navigation in the integrated data environment with different types of web recommendations.  Review of the related work in the fields of data integration and ontology matching and discussion of the contact points between the research described here and other related projects. The main contributions of the research described in this part of the thesis are the EC-Fuice architecture, the novel method for matching e-commerce ontologies based on combination of instance information and metadata information, the experimental results of ontology and instance matching performed by different matching algorithms and the classification of the types of recommendations which can be used on an integrated e-commerce website.

Os hiperdocumentos manipulados pelos sistemas hipertexto clássicos não podem ser utilizados em outro sistema ou plataforma. O padrão HyTime, uma extensão de SGML, constitui um esforço para permitir que documentos hipermídia e multimídia possam ser descritos em termos de sua estrutura e conteúdo e, desse modo, ser utilizados por quaisquer sistemas conformantes. Esse trabalho investiga os recursos para especificação de hiperdocumentos hipermídia de HyTime, em particular, aqueles providos por um Minimal hyperlinking HyTime document, uma classe de documentos definida pelo padrão. Como resultado deste trabalho, algumas estruturas tradicionais da literatura sobre hipertexto foram especificadas em um DTD através de construtores HyTime, um sistema básico hipermídia para autoria e apresentação dessas estruturas foi modelado, e a codificação da apresentação dessas estruturas através de applets Java foi implementada para que elas possam ser utilizadas no ambiente da WWW. / Classic Hypertext Systems have defined their documents so that they cannot be interchanged between systems or platforms. HyTime is an ISO standard, built as an extension of SGML, defined so as to allow the specification of multimedia and hypermedia documents to be made in terms of their stucture and contents ⎯ as a result hyperdocuments can be interchanged among any HyTime conforming systems. The work reported in this dissertation investigates what sort of documents are those conforming to Minimal hyperlinking HyTime documents. As a result, the work presents (a) the specification of a DTD that allows constructors supported in several classic hypertext systems, (b) the architecure of a conforming hypermedia environment and (c) a Java implementation for the constructors specified - so that the underlying classic hypertext structure can be made available in a open distributed hypermedia system such the WWW.

No description available.

Os hiperdocumentos manipulados pelos sistemas hipertexto clássicos não podem ser utilizados em outro sistema ou plataforma. O padrão HyTime, uma extensão de SGML, constitui um esforço para permitir que documentos hipermídia e multimídia possam ser descritos em termos de sua estrutura e conteúdo e, desse modo, ser utilizados por quaisquer sistemas conformantes. Esse trabalho investiga os recursos para especificação de hiperdocumentos hipermídia de HyTime, em particular, aqueles providos por um Minimal hyperlinking HyTime document, uma classe de documentos definida pelo padrão. Como resultado deste trabalho, algumas estruturas tradicionais da literatura sobre hipertexto foram especificadas em um DTD através de construtores HyTime, um sistema básico hipermídia para autoria e apresentação dessas estruturas foi modelado, e a codificação da apresentação dessas estruturas através de applets Java foi implementada para que elas possam ser utilizadas no ambiente da WWW. / Classic Hypertext Systems have defined their documents so that they cannot be interchanged between systems or platforms. HyTime is an ISO standard, built as an extension of SGML, defined so as to allow the specification of multimedia and hypermedia documents to be made in terms of their stucture and contents ⎯ as a result hyperdocuments can be interchanged among any HyTime conforming systems. The work reported in this dissertation investigates what sort of documents are those conforming to Minimal hyperlinking HyTime documents. As a result, the work presents (a) the specification of a DTD that allows constructors supported in several classic hypertext systems, (b) the architecure of a conforming hypermedia environment and (c) a Java implementation for the constructors specified - so that the underlying classic hypertext structure can be made available in a open distributed hypermedia system such the WWW.

No description available.

The issues discussed in this thesis are the problematics of making use of web casting systems in education. The aim of this research is the identification and analysis of web casting systems as a contemporary kind of audiovisual or multi-medial directed instructional media. A wide spectrum of properties and characteristics of web casting systems are subject to exploitation with the aim to understand their didactical specifics and possibilities of the functional use within the frame of innovation methods and techniques in education. The results of theoretical and empirical exploitation provide a solution for a model design of a web casting system. By detailing the theory of this specific area of didactical instruments, this thesis attempts to contribute to the development of information and technical education didactics and conscious of the growing importance of technologies for the support of education in the society, of knowledge and pedagogical science generally.

Die Extensible Markup Language (XML) hat sich seit ihrer ¨Erfindung¨ vor etwa drei Jahren zu einem strategischen Element bei neuen Computer- und Netz-Anwendungen entwickelt. Mittlerweile erfüllen sich auch einige der hochgesteckten Erwartungen, nicht zuletzt mit Hilfe von Werkzeugen aus dem Linux-Umfeld. Die sehr dynamische Entwicklung hat zahlreiche Richtungen. Neben ¨generischen¨ Werkzeugsystemen gibt es die server- und klientenseitige Interpretation diverser Stil- und Transformationsvorschriften. Standardisierte XML-basierte Spezialsprachen werden ¨herstellereigene¨ Binärformate ablösen und eine neue Qualität der Kooperation unterschiedlichster Anwendungen ermöglichen.