Hen-I Yang

Atlas: A Service-Oriented Sensor Platform: Hardware and Middleware to Enable Programmable Pervasive Spaces

Pervasive computing environments such as smart spaces require a mechanism to easily integrate, manage and use numerous, heterogeneous sensors and actuators into the system. However, available sensor network platforms are inadequate for this task. The goals are requirements for a smart space are very different from the typical sensor network application. Specifically, we found that the manual integration of devices must be replaced by a scalable, plug-and-play mechanism. The space should be assembled programmatically by software developers, not hardwired by engineers and system integrators. This allows for cost-effective development, enables extensibility, and simplifies change management. We found that in a smart space, computation and power are readily available and connectivity is stable and rarely ad-hoc. Our deployment of a smart house (an assistive environment for seniors) guided us to designing Atlas, a new, commercially available service-oriented sensor and actuator platform that enables self-integrative, programmable pervasive spaces. We present the design and implementation of the Atlas hardware and middleware components, its salient characteristics, and several case studies of projects using Atlas

A comparison of two programming models for pervasive computing

Establishing suitable programming models for pervasive spaces is essential in improving the productivity, enhancing the quality of pervasive systems, and creating an open platform for interoperability. Two different models, namely, the context-driven model and the service-oriented model, have been proposed and studied for their feasibilities as the foundation for implementing programmable pervasive spaces. We present these two alternatives and contrast their advantages and disadvantages.

A context-driven programming model for pervasive spaces

This paper defines a new, context-driven programming model for pervasive spaces. Existing models are prone to conflict, as it is hard to predict the outcome of interleaved actions from different services, or even to detect that a particular device is receiving conflicting instructions. Nor is there an easy way to identify unsafe contexts and the emergency remedy actions, or for programmers and users to grasp the complete status of the space. The programming model proposed here resolves these problems by improving coordination by explicitly defining the behaviors via context, and providing enhanced safety guarantees as well as a real-time, at-a-glance snapshot of the spaces status. We present this model by first revisiting the definitions of the three basic entities (sensors, actuators and users) and then deriving at the definition of the operational semantics of a pervasive space and its context. A scenario is provided to demonstrate both how programmers use this model as well as the advantages of the model over other approaches.

Reasoning about Human Intention Change for Individualized Runtime Software Service Evolution

While software evolution has been studied extensively in software engineering, few of these efforts have involved a systematic exploration of human epistemological attitudes, such as human desire and intention, as the driving force of software service evolution. Our work proposes a theoretical framework to monitor and reason about human intention and its changes, which in turn can be used to determine how software and services should evolve to be individualized and better serve each user. Extending the Situ framework, we explore the service satisfiability problem through sub-world coverage following Kripke semantics, which enjoys wide application in AI and other fields related to human epistemic reasoning.

Using Web Services for Medication Management in a Smart Home Environment

The Smart Home is a house equipped with technology to assist especially the elderly and persons with special needs. Smart Homes rely on Service-Oriented technology usually OSGi. Web Services (WS) receives little emphasis on Smart Homes, but they can be very useful for some applications. That is the case of management of medication as this task can become very difficult and involve different, remote parties. Several solutions have been proposed for applications like medications management but their lack of interoperability limits them. This paper presents a solution that integrates current systems and provides interoperability by using WS. The secure transfer of sensitive data among subsystems is achieved by using secure WS for communication purposes as shown by our prototyped implementation.

A taxonomy driven approach towards evaluating pervasive computing system

This paper presents taxonomical classification of pervasive computing system that allows characterizing the system and helps to identify most defining performance parameters for evaluation. Tremendous efforts have been put in the related research, but there is no standard or commonly accepted model to benchmark systems and to identify direction for future research. We survey various systems published in the literature and identify their distinctive features to construct a classification scheme, and the outcome is the taxonomy of pervasive computing systems that allows us to devise strategy on how to evaluate a wide variety of these systems.

Automatic service composition with heterogeneous service-oriented architectures

Service-Oriented Architecture is widely used to program pervasive spaces such as Smart Homes because of its capabilities to handle dynamic and heterogeneous environments. It is often the case that the services required are designed and implemented using different SOAs, such as OSGi and Web Services. Most of the current composition frameworks take a two-tier approach: those services following the same SOA can take advantage of service composition and runtime substitutions, while interactions between services of different SOAs require hardcoded service invocations that do not really provide full advantage of SOA. Some SOAs do not support features such as on-the-fly compositions or a searchable service directory. In this paper, we present a framework to compose and orchestrate services from different SOA implementations and provide the missing functionalities to support composition of heterogeneous SOAs. We present a case study and the performance analysis of the study to demonstrate the feasibility of our framework.

Fault-Resilient Pervasive Service Composition

Service-oriented architecture (SOA) promises an elegant model that can easily handle dynamic and heterogeneous environments such as pervasive computing systems. However, in reality, frequent failures of resource-poor and low-cost sensors greatly diminish the guarantees on reliability and availability expected from SOA. To provide a framework for building fault-resilient, service-oriented pervasive computing systems, we present a solution that combines a virtual sensor framework with WS-Pro/ASCT, a service composition mechanism. The use of virtual sensors enhances the availability of services, while the service composition solution ensures that the system can efficiently adapt to changes and failures in the environment. This approach also includes a novel probe-based monitoring technique for proactive collection of performance data and a Finite Population Queuing System Petri Net (FPQSPN) for modeling the performance of composed services.

Estimating the Relative Importance of Nodes in Social Networks

In social networks, nodes usually represent people and edges represent the relationship and connections between people. Ranking how important the nodes are with respect to some query nodes has a lot of applications in social networks. More often, people are interested in finding the Top-k most “relatively important” nodes with respect to some query nodes. A major challenge in this area of research is to define a function for measuring the “relative importance” between two nodes. In this paper, we present a measure called path probability to represent the connection strength of a between the ending node and the starting node. We proposed a measure of relative importance by using the sum of the path probabilities of all the “important” paths between a node with respect to a query node. Another challenge of computing the relative importance is the scalability issue. Most popular solutions are random walk based algorithms which involve matrix multiplication, and therefore are computationally too expensive for large graphs with millions of nodes. In this paper, by defining the path probability and introducing a small threshold value to determine whether a path is important or significant, we are able to ignore a lot of unimportant nodes so as to be able to efficiently identify the Top-k most relatively important nodes to the query nodes. Experiments are conducted over several synthetic and real graphs. The results are encouraging, and show a strong correlation between our approach and the well known random walk with restart algorithm.

Experience of Enhancing the Space Sensing of Networked Robots Using Atlas Service-Oriented Architecture

In this paper, we describe how we enhance the space sensing capabilities of the Ubiquitous Robotic Companion (URC) developed by ETRI Korea, by utilizing the plug-and-play service-oriented architecture provided by University of Floridas Atlas Platform. Based on our experience in deploying services using the Atlas Platform in smart houses, for the elderly and people with special needs, a requirement emerged for utilizing networked robots to assist elderly people in their activities of daily living. Networked robots consisting of sensors, actuators and smart devices can collaborate as mobile sensing platforms with the other networked robots in a smart space, providing a complex and sophisticated actuator and human interface. This paper describes our experience in designing and implementing system architecture to integrate URC robots into pervasive computing environments using the Atlas Platform. We also show how the integrated system is able to provide better services which enhance the space sensing capabilities of URCs in the smart space.