Judith Kelner, Pei-Chun Lin, Kelvin K.F. Tsoi, Zakaria Maamar, Patrick C.K. Hung, Dickson K.W. Chiu and Kevin K.W. Ho
Zakaria Maamar, Quan Z. Sheng, Samir Tata, Djamal Benslimane and Mohamed Sellami
In any critical system, high‐availability of software components like web services has so far been achieved through replication. Three replication strategies known as active…
Abstract
Purpose
In any critical system, high‐availability of software components like web services has so far been achieved through replication. Three replication strategies known as active, passive, and hybrid, describe for example how many replicas are needed, where to locate replicas, and how replicas interact with the original web service and among themselves if needed. The purpose of this paper is to show how replicates could be substituted with components that are similarly functional to the component that needs back‐up in case of failure.
Design/methodology/approach
After examination of the different existing replication strategies, it was decided to test the suitability of the proposed web services high‐availability approach based on communities for each strategy. To this end, the specification of web services using two behaviors, namely control and operational, was deemed appropriate.
Findings
The active replication strategy is the only strategy that could support the development of a web services high‐availability approach based on communities of web services.
Practical implications
The proposed approach has been validated in practice by deploying a JXTA‐based testbed. The experimental work has implemented the active replication strategy.
Originality/value
Software component high‐availability could be achieved by components that are similarly functional to this component, which permits the common limitations of existing replication strategies to be addressed.
Details
Keywords
The aim of the research is to discuss the design and development of a mobile application using two technologies known as software agent (SA) and mobile web services.
Abstract
Purpose
The aim of the research is to discuss the design and development of a mobile application using two technologies known as software agent (SA) and mobile web services.
Design/methodology/approach
The objectives were achieved by testing the integration of SAs and mobile web services into mobile applications. The approach suggested in the paper has relied on some modeling techniques such as service chart diagram and addressed some security issues.
Findings
It was found in the course of the work the necessity of being aware of the limitations of mobile devices, despite all the major developments that are happening. In addition, it was found that it is deemed appropriate to provide some modeling techniques which suit the development of mobile applications.
Originality/value
The paper discusses the concept of mobile web services. The paper is particularly useful to those who are in the field of mobile computing.
Details
Keywords
Eleftheria Katsiri, Jean Bacon and Alan Mycroft
The event‐driven paradigm is appropriate for context aware, distributed applications, yet basic events may be too low level to be meaningful to users. The authors aim to argue…
Abstract
Purpose
The event‐driven paradigm is appropriate for context aware, distributed applications, yet basic events may be too low level to be meaningful to users. The authors aim to argue that this bottom‐up approach is insufficient to handle very low‐level sensor data or to express all the queries users might wish to make.
Design/methodology/approach
The authors propose an alternative model for querying and subscribing transparently to distributed state in a real‐time, ubiquitous, sensor‐driven environment such as is found in Sentient Computing.
Findings
The framework consists of four components: a state‐based, temporal first‐order logic (TFOL) model that represents the concrete state of the world, as perceived by sensors; an expressive TFOL‐based language, the Abstract Event Specification Language (AESL) for creating abstract event definitions, subscriptions and queries; a higherorder service (Abstract Event Detection Service) that accepts a subscription containing an abstract event definition as an argument and in return publishes an interface to a further service, an abstract event detector; and a satisfiability service that applies classical, logical satisfiability in order to check the satisfiability of the AESL definitions against the world model, in a manner similar to a constraint‐satisfaction problem.
Originality/value
The paper develops a model‐based approach, appropriate for distributed, heterogeneous environments.
Details
Keywords
Abraham Bernstein, Peter Vorburger and Patrice Egger
People are subjected to a multitude of interruptions. In order to manage these interruptions it is imperative to predict a person's interruptability – his/her current readiness or…
Abstract
Purpose
People are subjected to a multitude of interruptions. In order to manage these interruptions it is imperative to predict a person's interruptability – his/her current readiness or inclination to be interrupted. This paper aims to introduce the approach of direct interruptability inference from sensor streams (accelerometer and audio data) in a ubiquitous computing setup and to show that it provides highly accurate and robust predictions.
Design/methodology/approach
The authors argue that scenarios are central for evaluating the performance of ubiquitous computing devices (and interruptability predicting devices in particular) and prove this on the setup employed, which was based on that of Kern and Schiele.
Findings
The paper demonstrates that scenarios provide the foundation for avoiding misleading results, and provide the basis for a stratified scenario‐based learning model, which greatly speeds up the training of such devices.
Practical implications
The direct prediction seems to be competitive or even superior to indirect prediction methods and no drawbacks have been observed yet.
Originality/value
The paper introduces a method for accurately predicting a person's interruptability directly from simple sensors without any intermediate steps/symbols.
Details
Keywords
Tarak Chaari, Frédérique Laforest and Augusto Celentano
The simple environment for context aware systems (SECAS) Project deals with the adaptation of applications to the context (user preferences and environment, terminal, etc.). The…
Abstract
Purpose
The simple environment for context aware systems (SECAS) Project deals with the adaptation of applications to the context (user preferences and environment, terminal, etc.). The authors aim to develop a platform which makes the services, data and the user interface of applications adaptable to different context situations.
Design/methodology/approach
Previous research has concentrated on how to capture context data and how to carry it to the application. The present work focuses on the impact of context on the application core. A case study in the medical field is also analysed.
Findings
The paper illustrates a new definition of the context which separates the application data from the parameters of the context. This definition helps to establish a complete study on how to adapt applications on their three dimensions (services, content and presentation) to the context.
Originality/value
The paper presents the SECAS platform, one that ensures the deployment of adaptive context‐aware applications.
Details
Keywords
Ronny Kramer, Marko Modsching and Klaus ten Hagen
The behavior of tourists strongly depends on the availability and quality of information. Too little information as well as too much can be disorienting and forces many tourists…
Abstract
Purpose
The behavior of tourists strongly depends on the availability and quality of information. Too little information as well as too much can be disorienting and forces many tourists to join the majority visiting major sights. This causes a few crowded places in contrast to many which are under‐utilized. A Destination Management Organization has the goal to spread tourists more evenly, whereas the tourists would like to enjoy the destination to its full potential according to their personal interests. The paper aims to focus on the issues surrounding the creation of a mobile tourist guide.
Design/methodology/approach
A field trial was conducted in the summer of 2005 to study the following questions as a precondition for the development: Is it possible to seed generic interest profiles in the mobile context that allow the accurate prediction of actual rankings? Are the interest profiles sufficiently diverse to base personalized tours on individual interest profiles instead of interest prototypes? How do personalized tours affect the spatial behavior of tourist? Three methods to elicit the generic preferences of tourist in the mobile context are compared with actual rankings using Spearman's rank order coefficient.
Findings
The diversity of the interest profiles is analyzed in various ways leading to the conclusion that personalized interest profiles are necessary. For the gathered profiles tours are computed and simulated in order to gain a first insight into the effect on the spatial behavior of tourists.
Originality/value
The dynamic tour guide is supporting both goals by means of pervasive computing based on the actual context which is defined by personal interests, location and schedule of a tourist. It enables a personalized, spontaneous and guided tour.
Details
Keywords
Kostas Stefanidis, Evaggelia Pitoura and Panos Vassiliadis
A context‐aware system is a system that uses context to provide relevant information or services to its users. While there has been a variety of context middleware infrastructures…
Abstract
Purpose
A context‐aware system is a system that uses context to provide relevant information or services to its users. While there has been a variety of context middleware infrastructures and context‐aware applications, little work has been done on integrating context into database management systems. The purpose of this paper is to consider a preference database system that supports context‐aware queries, that is, queries whose results depend on the context at the time of their submission.
Design/methodology/approach
The paper proposes using data cubes to store the dependencies between context‐dependent preferences and database relations and on‐line analytical processing techniques for processing context‐aware queries. This allows for the manipulation of the captured context data at various levels of abstraction, for instance, in the case of a context parameter representing location, preferences can be expressed, for example, at the level of a city, the level of a country or both. To improve query performance, the paper uses an auxiliary data structure, called context tree. The context tree stores results of past context‐aware queries indexed by the context of their execution. Finally, the paper outline the implementation of a prototype context‐aware restaurant recommender.
Findings
The use of context is important in many applications such as pervasive computing where it is important that users receive only relevant information.
Originality/value
Although there is much research on location‐aware query processing in the area of spatial‐temporal databases, integrating other forms of context in query processing is a rather new research topic.