A cache framework for nomadic clients of web services

This research explores the problems associated with caching of SOAP Web Service request/response pairs, and presents a domain independent framework enabling transparent caching of Web Service requests for mobile clients. The framework intercepts method calls intended for the web service and proceeds by buffering and caching of the outgoing method call and the inbound responses. This enables a mobile application to seamlessly use Web Services by masking fluctuations in network conditions. This framework addresses two main issues, firstly how to enrich the WS standards to enable caching and secondly how to maintain consistency for state dependent Web Service request/response pairs

In sickness and in Health? Dynamics of health and cohabitation in the United Kingdom

The purpose of this paper is to analyse the dynamics of cohabitation and functional impairments among older people. Our research has three main aims. Firstly, we want to analyse the effects of cohabitation on disability. Secondly, we want to study time trends in disability and cohabitation jointly to explore relationships between the two. Thirdly, we examine socioeconomic differences -- as captured by educational attainment -- in disability. These issues are of great interest from several points of view. Firstly, they address an emerging theoretical debate concerning the effects of cohabitation on health and contribute to a sparse empirical literature on the topic. Secondly, our findings are highly policy relevant. Concerning long-term care for older people, for example, cohabitation is of double importance: firstly, since people who cohabit tend to be healthier, and secondly, since a partner is the typical provider of informal care. In a time where family structures among the old are likely to change (due to changes in life expectancy and divorce rates), our research will be useful for planning purposes. Finally, the model can be used to simulate populations of certain characteristics. Hence, it can be used to derive insurance premiums in order to reduce the problem of selection effects in the market for long-term care insurance. Using the British Household Panel Survey dataset, we apply panel data and simulation techniques to exploit the longitudinal characteristic of the panel. We estimate the two dependent variables -- cohabitation status and disability -- jointly, and allow for time trends, age effects and unobserved heterogeneity. We find that there are systematic differences between single and cohabiting people so that a cross sectional analysis would overestimate the causal relationship; nevertheless, cohabitation has a strong and positive effect on health. Furthermore, we find that bereavement of a partner has a significant negative impact on health

Wide-Field InfraRed Survey Telescope (WFIRST) Final Report

In December 2010, NASA created a Science Definition Team (SDT) for WFIRST, the Wide Field Infra-Red Survey Telescope, recommended by the Astro 2010 Decadal Survey as the highest priority for a large space mission. The SDT was chartered to work with the WFIRST Project Office at GSFC and the Program Office at JPL to produce a Design Reference Mission (DRM) for WFIRST. Part of the original charge was to produce an interim design reference mission by mid-2011. That document was delivered to NASA and widely circulated within the astronomical community. In late 2011 the Astrophysics Division augmented its original charge, asking for two design reference missions. The first of these, DRM1, was to be a finalized version of the interim DRM, reducing overall mission costs where possible. The second of these, DRM2, was to identify and eliminate capabilities that overlapped with those of NASA's James Webb Space Telescope (henceforth JWST), ESA's Euclid mission, and the NSF's ground-based Large Synoptic Survey Telescope (henceforth LSST), and again to reduce overall mission cost, while staying faithful to NWNH. This report presents both DRM1 and DRM2.Comment: 102 pages, 57 figures, 17 table

An Information-Based Dynamic Extrapolation Model for Networked Virtual Environments

Various Information Management techniques have been developed to help maintain a consistent shared virtual world in a Networked Virtual Environment. However, such techniques have to be carefully adapted to the application state dynamics and the underlying network. This work presents a novel framework that minimizes inconsistency by optimizing bandwidth usage to deliver useful information. This framework measures the state evolution using an information model and dynamically switches extrapolation models and the packet rate to make the most information-efficient usage of the available bandwidth. The results shown demonstrate that this approach can help optimize consistency under constrained and time-varying network conditions

Execution Autonomy in Distributed Transaction Processing

We study the feasibility of execution autonomy in systems with asynchronous transaction processing based on epsilon-serializability (ESR). The abstract correctness criteria defined by ESR are implemented by techniques such as asynchronous divergence control and asynchronous consistency restoration. Concrete application examples in a distributed environment, such as banking, are described in order to illustrate the advantages of using ESR to support execution autonomy

An Information-Theoretic Framework for Consistency Maintenance in Distributed Interactive Applications

Distributed Interactive Applications (DIAs) enable geographically dispersed users to interact with each other in a virtual environment. A key factor to the success of a DIA is the maintenance of a consistent view of the shared virtual world for all the participants. However, maintaining consistent states in DIAs is difficult under real networks. State changes communicated by messages over such networks suffer latency leading to inconsistency across the application. Predictive Contract Mechanisms (PCMs) combat this problem through reducing the number of messages transmitted in return for perceptually tolerable inconsistency. This thesis examines the operation of PCMs using concepts and methods derived from information theory. This information theory perspective results in a novel information model of PCMs that quantifies and analyzes the efficiency of such methods in communicating the reduced state information, and a new adaptive multiple-model-based framework for improving consistency in DIAs. The first part of this thesis introduces information measurements of user behavior in DIAs and formalizes the information model for PCM operation. In presenting the information model, the statistical dependence in the entity state, which makes using extrapolation models to predict future user behavior possible, is evaluated. The efficiency of a PCM to exploit such predictability to reduce the amount of network resources required to maintain consistency is also investigated. It is demonstrated that from the information theory perspective, PCMs can be interpreted as a form of information reduction and compression. The second part of this thesis proposes an Information-Based Dynamic Extrapolation Model for dynamically selecting between extrapolation algorithms based on information evaluation and inferred network conditions. This model adapts PCM configurations to both user behavior and network conditions, and makes the most information-efficient use of the available network resources. In doing so, it improves PCM performance and consistency in DIAs