Amirhosein Taherkordi

A resource oriented integration architecture for the Internet of Things

The vision of the Internet of Things (IoT) foresees a future Internet incorporating smart physical objects that offer hosted functionality as IoT services. These services when integrated with the traditional enterprise level services form the creation of ambient intelligence for a wide range of applications. To facilitate seamless access and service life cycle management of large, distributed and heterogeneous IoT resources, service oriented computing and resource oriented approaches have been widely used as promising technologies. However, a reference architecture integrating IoT services into either of these two technologies is still an open research challenge. In this article, we adopt the resource oriented approach to provide an end-to-end integration architecture of front-end IoT devices with the back-end business process applications. The proposed architecture promises a programmer friendly access to IoT services, an event management mechanism to propagate context information of IoT devices, a service replacement facility upon service failure, and a decentralized execution of the IoT aware business processes.

Programming sensor networks using REMORA component model

The success of high-level programming models in Wireless Sensor Networks (WSNs) is heavily dependent on factors such as ease of programming, code well-structuring, degree of code reusability, and required software development effort. Component-based programming has been recognized as an effective approach to meet such requirements. Most of componentization efforts in WSNs were ineffective due to various reasons, such as high resource demand or limited scope of use. In this paper, we present Remora, a new approach to practical and efficient component-based programming in WSNs. Remora offers a well-structured programming paradigm that fits very well with resource limitations of embedded systems, including WSNs. Furthermore, the special attention to event handling in Remora makes our proposal more practical for WSN applications, which are inherently event-driven. More importantly, the mutualism between Remora and underlying system software promises a new direction towards separation of concerns in WSNs. Our evaluation results show that a well-configured Remora application has an acceptable memory overhead and a negligible CPU cost.

Adaptable service composition for very-large-scale Internet of Things systems

The (future) Internet of Things (IoT), with service composition point of view, raises additional challenges especially with respect to handling the scale, dynamicity and heterogeneity of the target networking environment. Therefore, the services offered by IoT resources can not be composed by simply extending existing Service Oriented Architecture (SOA) approaches, since it requires the integration of a huge number of real world services that demands for the user-centric and a situation-aware composition process. In this paper, we present an architectural approach that enables efficient and adaptive composition of services by locally orchestrating the distributed web-enabled services in Very Large Scale (VLS) IoT systems and globally choreographing the different enterprise level Web services.

Optimizing sensor network reprogramming via in situ reconfigurable components

Wireless reprogramming of sensor nodes is a critical requirement in long-lived wireless sensor networks (WSNs) addressing several concerns, such as fixing bugs, upgrading the operating system and applications, and adapting applications behavior according to the physical environment. In such resource-poor platforms, the ability to efficiently delimit and reconfigure the necessary portion of sensor software—instead of updating the full binary image—is of vital importance. However, most existing approaches in this field have not been adopted widely to date due to the extensive use of WSN resources or lack of generality. In this article, we therefore consider WSN programming models and runtime reconfiguration models as two interrelated factors and we present an integrated approach for addressing efficient reprogramming in WSNs. The middleware solution we propose, <scp<RemoWare</scp<, is characterized by mitigating the cost of post-deployment software updates on sensor nodes via the notion of in situ reconfigurability and providing a component-based programming abstraction in order to facilitate the development of dynamic WSN applications. Our evaluation results show that <scp<RemoWare</scp< imposes a very low energy overhead in code distribution and component reconfiguration and consumes approximately 6% of the total code memory on a <scp<TelosB</scp< sensor platform.

A Middleware Layer Mechanism for QoS Support in Wireless Sensor Networks

Wireless sensor networks need different satisfying Quality of Service (QoS) levels for their successful operation. Providing QoS support for wireless sensor networks at the middleware layer is a new research area. This paper proposes a real-time and faulttolerant mechanism as a middleware for wireless sensor networks which operates according to sensor nodes’ requirements like data rate and energy. A service-based middleware receives users’ QoS requirements about wireless sensor networks’ services and guarantees time critical responses in an efficient and scalable way in a cluster-based organization. The proposed mechanism can support multiple sink nodes’ QoS requirements and can utilize the redundancy of wireless sensor networks, especially multiple service providers to guarantee fault tolerance. It uses local information to schedule critical messages, and monitors nodes in an energy efficient way. Evaluation results show that the cost of real-time support is nearly low and can meet real-time requirements.

RESTful integration of heterogeneous devices in pervasive environments

More and more home devices are equipped with advanced computational capabilities to improve the user satisfaction (e.g., programmable heating system, Internet TV). Although these devices exhibit communication capabilities, their integration into a larger home monitoring system remains a challenging task, partly due to the strong heterogeneity of technologies and protocols. In this paper, we therefore propose to reconsider the architecture of home monitoring systems by focusing on data and events that are produced and triggered by home devices. In particular, our middleware platform, named DigiHome, applies i) the REST (REpresentational State Transfer) architectural style to leverage on the integration of multi-scale systems-of-systems (from Wireless Sensor Networks to the Internet) and ii) a CEP (Complex Event Processing) engine to collect information from heterogeneous sources and detect application-specific situations. The benefits of the DigiHome platform are demonstrated on smart home scenarios covering home automation, emergency detection, and energy saving situations.

A self-adaptive context processing framework for wireless sensor networks

Wireless sensor networks are increasingly being exploited in ubiquitous computing environments as one of the main platforms for gathering context data. In order to continuously observe the environment context during a long period, the sensor node should be considered itself as a context-aware device having particular contextual parameters, such as residual energy or sample rate. Existing work in the field of context-aware computing mostly considers the sensor node as a context data collector agent, regardless of the concern of the nodes context elements. In this paper, we first propose an approach for modeling sensor network context information, and then, we introduce a middleware framework that maps our context model to software components, processes the context data, and implements the context model. For this purpose, we propose the notion of context node, which is the building block of our context processing framework. The proposed solution is exemplified in the shape of a home monitoring application. Using the proposed framework, the sensor application can adapt itself to the current situation in the environment through executing a high-level context model describing both the context information to process and the adaptation actions to perform.

Load-balance of intra/inter-MANET traffic over multiple internet gateways

The paper first gives an overview of the required functions for providing Internet connectivity and mobility management for mobile ad-hoc networks (MANETs). Internet gateway selection is one of these functions. Since multiple Internet gateways might exist on the same MANET domain, a hybrid metric for Internet gateway selection is proposed as a replacement of the shortest hop-count metric. The hybrid metric provides load-balancing of intra/inter-MANET traffic. Simulation results show that ad-hoc routing protocols, using our proposed metric get better performance in terms of packet delivery ratio and transmission delay, at the cost of slightly increased signalling overhead.

Dependability Considerations in Wireless Sensor Networks Applications

Recently, the use of wireless sensor networks has spread to applications areas that are not viable or costefficient to be run on other types of networks. Due to some critical tasks done in these types of networks, the majority of sensor networks applications should be dependable and should be run continuously and reliably without interruption. Hence, the two more significant dependability factors that should be nowadays taken into account in developing wireless sensor networks applications are ‘availability’ and ‘reliability’ of application services. The specific characteristics and constraints of wireless sensor networks require a different interpretation of these two factors when developing applications for such networks. In this paper, we propose a middleware layer mechanism for satisfying these two factors as more important dependability issues in sensor networks applications. We propose an event-based middleware service that is specifically designed for wireless sensor networks in which a group of sensor nodes forms a cluster and a replicated service is run on each cluster head. The communication model among cluster members and cluster head is based on the publish/subscribe scheme. We show how the replicated services and communication model in cluster nodes satisfy dependability issues and increase the availability and reliability of applications running under the proposed middleware.

The DigiHome Service-Oriented Platform

Nowadays, the computational devices are everywhere. In malls, offices, streets, cars, and even homes, we can find devices providing and consuming functionality to improve the user satisfaction. These devices include sensors that provide information about the environment state (e.g., temperature, occupancy, light levels), service providers (e.g., Internet TVs, GPS), smartphones (that contain user preferences), and actuators that act on the environment (e.g., closing the blinds, activating the alarm, changing the temperature). Although these devices exhibit communication capabilities, their integration into a larger monitoring system remains a challenging task, partly because of the strong heterogeneity of technologies and protocols. Therefore, in this article, we focus on home environments and propose a middleware solution, called DigiHome, that applies the Service Component Architecture (SCA) component model to integrate data and events generated by heterogeneous devices in this kind of environments. DigiHome exploits the SCA extensibility to incorporate the REpresentational State Transfer (REST) architectural style and, in this way, leverages on the integration of multiscale systems‐of‐systems (from wireless sensor networks to the Internet). Additionally, the platform applies Complex Event Processing technology that detects application‐specific situations. We claim that the modularization of concerns fostered by DigiHome and materialized in a service‐oriented architecture, makes it easier to incorporate new services and devices in smart home environments. The benefits of the DigiHome platform are demonstrated on smart home scenarios covering home automation, emergency detection, and energy saving situations. Copyright