Data integration, in the context of the web, faces new problems, due in particular to the heterogeneity of sources, to the fragmentation of the information and to the absence of a unique way to structure and view information. In such areas, the traditional paradigms, on which database foundations are based (i.e. client server architecture, few sources containing large information), have to be o...

In this paper we present a model for dynamically scheduling HTTP requests across clusters of servers, optimizing the use of client resources as well as the scattered server nodes. We also present a system, H-SWEB, implementing our techniques and showing experimental improvements of over 250%, which have been achieved through utilizing a global approach to scheduling requests. This is the first ...

This paper compares popular client and server architectures used for groupware. It presents a client framework and evaluates native, installed clients, Java-based applications, and web-based architectures. It also presents a server framework and evaluates databases, thin servers, application servers, and a custom collaborative server. Lessons learned are provided for each architecture. Native a...

The three-tier client/server architecture is an evolution of the traditional two-tier model, and is receiving increased interest, particularly for large business applications. The main difference is that in a three-tier architecture, most of the functionality is separated out in a middle layer, called application servers, as shown in figure 1. Also, each client can use several application serve...

We advocate a new architecture for distributed systems supporting mobility. In this architecture an intermediary is interposed between client and server. Its purpose is to lter or delay all but the most essential data that would travel over the slow link to the mobile host, as instructed by the client. The goal of our work is to provide a general framework to ease the installation and managemen...

Discrete EVent Specification (DEVS) environments are known to be implemented over middleware systems such as HLA, RMI, CORBA and others. DEVS exhibits concepts of systems theory and modeling and supports capturing the system behavior from the physical and behavioral perspectives. Further, they are implemented using Objectoriented languages like Java and C++. This research work uses the Java pla...

Conventional two-tier databases have shown performance limitations in the presence of many concurrent clients. We propose logical grouping of clients (or clustering) as the means to improve the performance of collaborative networked databases. In this paper, we discuss a three-tier client-server database architecture (3t-CSD) featuring the above partitioning. The proposed clustering is based on...

This paper is part of a large pattern language (Crossing Chasms) currently under development by Bruce Whitenack of The Object People and myself. The pattern language as a whole addresses the issues faced by teams trying to build large clientserver systems using Object Technology and Relational data stores. This section of Crossing Chasms addresses issues faced by project teams who are just begi...

In today’s world, many statistical questions require the use of computationalassistance. Our approach, presented in this thesis, combines the possibilities of the powerful statistical software environment XploRe, with the advantagesof distributed client/server applications, and the opportunities offered by theInternet. In order to offer the client access to a large community, the Ja...

Mobile information technology can help first responders assist patients more quickly, reliably, and safely, while focusing resources on those most in need. Yet the disaster setting complicates reliable networked computing. The WIISARD client-server architecture provides mobile IT support for medical response in disasters. Cached remote objects (CROs) are shared via publish/subscribe, enabling d...