An approach for designing and implementing middleware in wireless sensor networks

In this paper, we propose an approach for designing and implementing a middleware for data dissemination in Wireless Sensor Networks (WSNs). The designing aspect considers three perspectives: device, network and application. Each application layer is implemented as an independent Component Object Model (COM) Project which offers portability, security, reusability and domain expertise encapsulation. For result analysis, the percentage of success is used as performance parameter. Such analysis reveals that the middleware enables to greatly increase the percentage of success of the messages disseminated in a WSN

Virtual Database as a Development Platform

Tässä työssä tarkastellaan Movenium Oy:n toteuttamaa virtuaalista tietokantaratkaisua nimeltä Collector. Työn alussa esitellään tarvittava teoria tietokannoista ja SaaS-palveluista. Kirjallisuusosuudessa verrataan virtuaalista tietokantaratkaisua eri tietokantoihin, kuten perinteiseen relaatiomalliin sekä NoSql-tietokantoihin. Tutkimuksen aiheena on Collectorin kuormankestokapasiteetti ja sen riittävyys Movenium Oy:n tarpeisiin tulevaisuudessa. Tutkimus on toteutettu ohjelmalla, joka kasvattaa tietokantaa satunnaisdatalla ja suorittaa hakuja. Hakujen suoritusaikojen perusteella voidaan päätellä tietokantaratkaisun kuormankestävyys.This bachelor’s thesis is about virtual database solution called Collector. First section describes the needed theory about databases and SaaS. After theory part, Collector is being evaluated against different kind of database solutions. Both relational databases and NoSql-databases are covered. Main focus of the research is to review Collector's performance and capacity. This is done by a script which writes data to database and executes search queries to determine how long does the searches take

A Delay-Constrained Middleware Architecture for Disseminating Information in Wireless Sensor Networks

RÉSUMÉ Les réseaux de capteurs sans fil (WSNs: Wireless Sensor Networks) constituent un domaine de recherche très actif et qui reçoit beaucoup d'attention de la part de la communauté scientifique. Ces réseaux offrent la possibilité de surveiller, de rassembler et de transmettre des données de l'environnement, en utilisant des noeuds appelés capteurs. Ces données sont généralement recueillies par une entité centrale qui les rend disponibles aux utilisateurs et à d’autres réseaux, comme Internet et les réseaux cellulaires. À cette fin, il existe des techniques, dites de diffusion, qui s’occupent de transférer les données à toutes les destinations. En particulier, le choix d’une technique de diffusion dépend de l'application utilisée. Par exemple, les applications à contraintes de délai imposent une contrainte de délai de bout-en-bout au processus de diffusion des données afin de coordonner des opérations de recherche et de sauvetage, et d'alerter les gens lors d’une opération d’urgence. Ce mémoire propose une architecture d'intergiciel qui sert de médiateur entre les applications à contraintes de délai et les techniques de diffusion de données. Une preuve de concept est faite pour montrer la faisabilité de l'architecture et l'efficacité d'un tel médiateur. L’analyse du prototype montre, entre autres, que le pourcentage de succès de transmission de l’intergiciel est largement supérieur à celui des protocoles individuels, tels que le service de messagerie (SMS: Short Message Service), le courriel et Twitter. ----------ABSTRACT Wireless Sensor Networks (WSNs) have been gaining a lot of attention from the research community. They offer the possibility to monitor and collect information from the environment, using small sensor nodes. Generally, the information is later transmitted towards a centralized entity that serves as an interface to users, or to other networks (e.g., cellular networks or Internet). Data dissemination techniques are in charge of the sending process to all destinations. The technique is chosen depending on the application. For instance, delay-constrained applications impose end-to-end delay constraints to coordinate rescue operations and warn people about critical events. This thesis proposes a middleware architecture that serves as a mediator between delay-constrained applications and data dissemination techniques. The architecture is intended to disseminate information from wireless sensor networks to Internet and cellular networks, considering end-to-end delay constraints. A proof of concept is done to validate its feasibility and effectiveness. More specifically, the results show that the percentage of success is much better using a middleware as a mediator than using individual protocols for data dissemination, such as Short Message Service (SMS), email and twitter

Transparent and adaptive application partitioning using mobile objects

The dynamic nature and heterogeneity of modern execution environments such as mobile, ubiquitous, and grid computing, present major challenges for the development and efficient execution of the applications targeted for these environments. In particular, applications tailored to run in a specific environment will show different and most likely sub-optimal behaviour when executed on a different and/or dynamic environment. Consequently, there has been growing interests in the area of application adaptation which aims to enable applications to cope with the varying execution environments. Adaptive application partitioning, a specific form of non-functional adaptation involving distribution of mobile objects across multiple host machines, is of particular interest to this thesis due to the diversity of its uses. In this approach, certain runtime information (known as context) is used to allow an object-oriented application to adaptively (re)adjust the placement of its objects during its execution, for purposes such as improving application performance and reliability as well as balancing resource utilisation across machines. Promoting the adoption of such adaptation requires a process that requires minimal human involvement in both the execution and the development of the relevant application. These challenges establish the main goals and contributions of this work, which include: 1) Proposing an effective application partitioning solution via the adoption of a decentralised adaptation strategy known as local adaptation. 2) Enabling adaptive application partitioning which does not require human intervention, through automatic collection of required information/context. 3) Proposing a solution for transparently injecting the required adaptation functionality into regular object-oriented applications allowing significant reduction of the associated development cost/effort. The proposed solutions have been implemented in a Java-based adaptation framework called MobJeX. This implementation, which was used as a test bed for the empirical experiments undertaken in this study, can be used to facilitate future research relevant to this particular study

Evaluating the Performance of Middleware Load Balancing Strategies

Middleware is increasingly used to develop scalable distributed applications. One way to improve the scalability of distributed applications is via load balancing middleware that can take into account dynamic system behavior, distributed application state, and client request content. Limitations with earlier generations of middleware load balancing services constrained their applicability and required tedious and errorprone redevelopment of these services for new distributed applications. Recent advances in middleware load balancing services overcome these limitations by supporting (1) adaptive and non-adaptive load balancing strategies, (2) load metric neutrality that allows middleware load balancing to be applied to a wider range of distributed applications, and (3) server-side transparency that makes it easier to integrate load balancing middleware with distributed application software