A distributed-object infrastructure for corporate websites

A corporate website is the virtual representation of a cor-poration or organization on the Internet. Corporate web-sites face numerous problems due to their large size and complexity, and the nonscalability of the underlying Web infrastructure. Current solutions to these problems gener-ally rely on traditional scaling techniques such as caching and replication. These are usually too restrictive, however; taking a one-size-fits-all approach and applying the same solution to every document. We propose Globe as a founda-tion upon which to build scalable corporate websites, and introduce GlobeDoc, a website model based on Globe dis-tributed shared objects. This paper describes GlobeDoc, highlighting the design and technical details of the infras-tructure. 1

The Architectural Design of Globe: A Wide-Area Distributed System

. Developing large-scale wide-area applications requires an infrastructure that is presently lacking entirely. Currently, applications have to be built on top of raw communication services, such as TCP connections. All additional services, including those for naming, replication, migration, persistence, fault tolerance, and security, have to be implemented for each application anew. Not only is this a waste of effort, it also makes interoperability between different applications difficult or even impossible. We present a novel, object-based framework for developing wide-area distributed applications. The framework is based on the concept of a distributed shared object, which has the characteristic feature that its state can be physically distributed across multiple machines at the same time. All implementation aspects, including communication protocols, replication strategies, and distribution and migration of state, are part of an object and are hidden behind its interface. The curren..

Analysis of the charging of the SCATHA (P78-2) satellite

The charging of a large object in polar Earth orbit was investigated in order to obtain a preliminary indication of the response of the shuttle orbiter to such an environment. Two NASCAP (NASA Charging Analyzer Program) models of SCATHA (Satellite Charging at High Altitudes) were used in simulations of charging events. The properties of the satellite's constituent materials were compiled and representations of the experimentally observed plasma spectra were constructed. Actual charging events, as well as those using test environments, were simulated. Numerical models for the simulation of particle emitters and detectors were used to analyze the operation of these devices onboard SCATHA. The effect of highly charged surface regions on the charging conductivity within a photosheath was used to interpret results from the onboard electric field experiment. Shadowing calculations were carried out for the satellite and a table of effective illuminated areas was compiled

Unifying Internet Services Using Distributed Shared Objects

Developing wide area applications such as those for sharing data across the Internet is unnecessarily difficult. The main problem is the widespread use of a communication paradigm that is too low level. We will show how wide area application development can be made easier when using distributed shared objects instead of a communication-oriented model. An object in our model is physically distributed, with multiple copies of its state on different machines. All implementation aspects such as replication, distribution, and migration of state, are hidden from users through an object's interface. In this paper, we concentrate on the application of distributed shared objects, by providing an outline of a middleware solution that permits integration of the Internet services for e-mail, News, file transfer, and Web documents. vrije Universiteit Faculty of Mathematics and Computer Science 1 Introduction Constructing wide area applications, such as those for sharing data across the Internet,..

Improving professional practice in the disclosure of a diagnosis of dementia : a modeling experiment to evaluate a theory-based intervention

The original publication is available at www.springerlink.com.Peer reviewedPostprin

Additional application of the NASCAP code. Volume 1: NASCAP extension

The NASCAP computer program comprehensively analyzes problems of spacecraft charging. Using a fully three dimensional approach, it can accurately predict spacecraft potentials under a variety of conditions. Several changes were made to NASCAP, and a new code, NASCAP/LEO, was developed. In addition, detailed studies of several spacecraft-environmental interactions and of the SCATHA spacecraft were performed. The NASCAP/LEO program handles situations of relatively short Debye length encountered by large space structures or by any satellite in low earth orbit (LEO)