Chun-Feng Liao

Service-Oriented Smart-Home Architecture Based on OSGi and Mobile-Agent Technology

The architecture of a conventional smart home is usually server-centric and thus causes many problems. Mobile devices and dynamic services affect a dynamically changing environment, which can result in very difficult interaction. In addition, how to provide services efficiently and appropriately is always an important issue for a smart home. To solve the problems caused by traditional architectures, to deal with the dynamic environment, and to provide appropriate services, we propose a service-oriented architecture (SOA) for smart-home environments, based on Open Services Gateway Initiative (OSGi) and mobile-agent (MA) technology. This architecture is a peer-to-peer (P2P) model based on multiple OSGi platforms, in which service-oriented mechanisms are used for system components to interact with one another, and MA technology is applied to augment the interaction mechanisms

Toward a Message-Oriented Application Model and its Middleware Support in Ubiquitous Environments

Context-awareness has become a distinguishing feature of Ubiquitous systems. Contrary to desktop and Web applications, Ubiquitous applications gather environmental context and provide services without user intervention. In this paper, we propose a message- oriented application model that is capable of modeling both user and system initiative interaction paradigms by N, Ramakrishan, et al (2002). Systems designed based on this model are inherently loosely-coupled and scalable. Results of this research include a systematic development procedure and its supporting middleware. We show the feasibility of this model by constructing several Ubiquitous applications for two dissimilar demo sites, and discuss experiences when adopting this model.

Toward Reliable Service Management in Message-Oriented Pervasive Systems

Reliability is one of the key challenges of pervasive systems. Numerous message-oriented architectures and service discovery protocols have been proposed to support service management in pervasive systems. Nevertheless, few researches have been done to improve the reliability of pervasive systems. This paper attempts to propose a reliable service management framework by formally defining a message-oriented service application model and protocols that facilitate autonomous composition, failure detection, and recovery of services. Proposed approaches are realized by constructing a developers toolkit that enables rapid-prototyping of services. We evaluate the proposed approach by first proving the reliability property and then conducting experiments on recovery rate and performance. The results show that the recovery rate can be greatly improved by the proposed approach. Furthermore, the services developed by using the proposed approach are capable of integrating heterogeneous software/hardware, and can be deployed in dissimilar sites with little efforts.

PSMP: A Fast Self-Healing and Self-Organizing Pervasive Service Management Protocol for Smart Home Environments

Current trends suggest that the smart home systems should be adaptive and robust. Many service-oriented architectures and discovery protocols for the smart home environments have been proposed to support on-line re-composition of home services in reaction to changing environments. Nevertheless, few researches have been done to improve the robustness of smart home systems. This paper attempts to propose a service management protocol that supports fast self-healing and self-organizing of home services by enhancing SSDP/UPnP with two protocol extensions and a lightweight heartbeat mechanism. Experiment results show that for average scale of services (less than 10 service components), the proposed protocol is capable of activating a service and recovering a failed service within 1200 ms and 2000 ms, respectively.

An efficient autonomous failure recovery mechanism for UPnP-based message-oriented pervasive services

Service discovery is an interesting challenge in highly dynamic pervasive environments such as smart living spaces. In addition to adaptation to varied environments, autonomous failure recovery and activation of services are two fundamental issues of a service discovery protocol in order to achieve high service availability. We have introduced an enhanced version of UPnPs simple service discovery protocol (SSDP), which aims to fulfill these two fundamental issues. However, our experiences in the previous work show that the failure recovery performance is not desirable due to the multicast mechanism used by SSDP. In this paper, we propose a supporting data structure, mapped eviction SND tree, composed of a set of specialized mapped-trees to speed up the failure recovery process. The system with this structure is aware of existing service nodes and need not to perform the discovery procedure again when failure is detected. Hence, the time for restoring the failed service is minimized. Experiment results show that the proposed approach helps reducing the failure recovery time up to 90 percent in average. Issues concerning maintenance and collaboration between the sets of internal data structures are also discussed in this paper.

A spontaneous preference aware service composition framework for Message-Oriented Pervasive systems

Current trends suggest that the Pervasive systems should be adaptive and flexible. Many Message-Oriented Pervasive systems have been proposed to support on-line self-composition of services in reaction to changing contexts. However, most existing service composition mechanisms either do not consider user preferences or use proprietary typing systems. In this paper, we propose an extensible ontology-based autonomous service composition framework for Message-Oriented Pervasive systems. System developers can reconfigure this framework according to their application domains by overriding default hook functions. Experimental results show that the superiority1 of the proposed approach become obvious along with increasing number of nodes.

Message-Efficient Service Management Schemes for MOM-Based UPnP Networks

The use of message-oriented middleware (MOM) in pervasive systems has increased noticeably because of its flexible and failure-tolerant nature. Meanwhile, decentralized service management protocols such as UPnP are believed to be more suitable for administrating applications in small-scale pervasive environments such as smart homes. However, administering MOM-based pervasive systems by UPnP often suffers from network flood problems due to the replications of too many unnecessary messages. This paper presents several traffic reduction schemes, namely, decomposing the multicast traffic, service-based node searching, heartbeat by decomposing the multicast traffic, and on-demand heartbeat, which reduce the replications of unnecessary messages in MOM-based UPnP networks. The analytical predictions agree well with the simulated and experimental results, which show that the message counts of presence and leave announcements, node searching, and heartbeat can be greatly reduced.

Boosting the efficiency of the reliable service management protocol for message-oriented pervasive systems in smart home environments

The use of Message-Oriented architectures in Pervasive systems has increased noticeably because of their failure tolerant and loosely-coupled natures. Meanwhile, nondirectory-based service management protocols are believed to be more suitable for small scale Pervasive environments such as smart homes. However, the paradigm mismatch causes nondirectory-based protocols suffer from network flooding problems due to too many unnecessary messages. In this paper, we present efficiency boosting strategies for PSMP, an UPnP/SSDP-based Message-Oriented reliable service management protocol. Analysis results show that the proposed approaches are capable of reducing not only the message count of the Presence/Leave Announcement and Node Discovery down to 1/10 in the worst case, but also the complexity of heartbeat from O{W1)toO{W) where W is the number of serving computing entities.

A Rotating Roll-Call-Based Adaptive Failure Detection and Recovery Protocol for Smart Home Environments

Smart homes generally differ from other pervasive environments such as office environments. Homes are lack of system administrators to fix faulty services on the spot. Nevertheless, services in smart homes can be critical especially when they involve health and wellness services, since faulty services can lead to unexpected/undesirable consequences. Therefore, robustness and availability are two fundamental requirements for service management protocols or middleware at homes. In this paper, we propose an efficient and adaptive failure detection and recovery mechanism, namely, the Rotating Roll-Call-based Protocol (RRCP), for home environments. Failures of software components are detected efficiently with a roll-call-based algorithm in which the roll-caller is elected periodically. Adaptive techniques and reliable UDP are adopted to maintain home network stability. Experimental results show that the proposed protocol is robust even under elevated failure rates.

Unifiable Preference Expressions for Pervasive Service Composition

Composing services in a pervasive environment usually involves user-in-the-loop adaption which is absent in most of the traditional enterprise service composition mechanisms. In such environment, the criteria for selecting and ranking services are usually specified by users, which tend to be vague and subjective. The criteria can be contradictory and the activated services can interfere with one another. This paper addresses these issues by defining a unifiable and negotiable expression language called the Preference Expression that is capable of specifying both enumerative/numeric as well as mandatory/negotiable user preferences. A set of unification rules for possible conflicting preferences is also derived. Experimental results show that the proposed approach is able to achieve high composition precision and maintains reasonable success rate at the same time.