• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권3호
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• pp.971-989
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• 2015

With the development of cloud computing, more and more Web services are deployed on geo-distributed datacenters and are offered to cloud users all over the world. Through service composition technologies, these independent fine-grain services can be integrated to value-added coarse-grain services. During the composition, a number of Web services may provide the same function but differ in performance. In addition, the distribution of cloud datacenters presents a geographically dispersive manner, which elevates the impact of the network on the QoS of composite services. So it is important to select an optimal composition path in terms of QoS when many functionally equivalent services are available. To achieve this objective, we first present a graph model that takes both QoS of Web services and QoS of network into consideration. Then, a novel approach aiming at selecting the optimal composition path that fulfills the user's end-to-end QoS requirements is provided. We evaluate our approach through simulation and compare our method with existing solutions. Results show that our approach significantly outperforms existing solutions in terms of optimality and scalability.

• 한국컴퓨터정보학회논문지
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• 제8권2호
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• pp.129-134
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• 2003

본 논문은 액티브네트워크 상의 웹 캐싱을 위한 서비스 컴포지션에 관하여 언급하였다. 액티브네트워크에서는 사용자의 요구사항에 맞게 서비스들을 빠르게 재구성하기 위한 서비스 컴포지션에 대한 요구사항이 대두되고 있다. 이러한 요구사항을 지원하기 위해서 우리는 액티브 네트워크상에서 웹 캐싱을 위한 서비스 컴포지션의 설계 및 구현에 관하여 언급하였다.

• 한국컴퓨터정보학회논문지
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• 제22권9호
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• pp.91-97
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• 2017

IoT (Internet of Things) systems are based on heterogeneous hardware systems of different types of devices interconnected each other, ranging from miniaturized and low-power wireless sensor node to cloud servers. These IoT systems composed of heterogeneous hardware utilize data sets collected from a particular set of sensors or control designated actuators when needed using open APIs created through abstraction of devices' resources associated to service applications. However, previously existing IoT services have been usually developed based on vertical platforms, whose sharing and exchange of data is limited within each industry domain, for example, healthcare. Such problem is called 'data silo', and considered one of crucial issues to be solved for the success of establishing IoT ecosystems. Also, IoT services may need to dynamically organize their services according to the change of status of connected devices due to their mobility and dynamic network connectivity. We propose a way of dynamically composing IoT services under the concept of WoT (Web of Things) where heterogeneous devices across different industries are fully integrated into the Web. Our approach allows developers to create IoT services or mash them up in an efficient way using Web objects registered into multiple standardized horizontal IoT platforms where their resources are discoverable and accessible. A Web-based service composition tool is developed to evaluate the practical feasibility of our approach under real-world service development.

• 정보처리학회논문지D
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• 제15D권6호
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• pp.879-888
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• 2008

최근 웹 서비스가 다양한 응용 분야에 도입되면서 모바일 환경에서도 웹서비스 조합 어플리케이션의 개발이 활발하다. 모바일 환경에서 여러 개 서비스를 지원하는 사용자 인터페이스는 각 서비스의 호출과 응답 확인을 위한 여러 개의 뷰가 필요하고 서비스 간의 조합 순서와 흐름을 분석할 필요가 있다. 본 논문에서는 서비스 집합의 명세로부터 프리젠테이션 요소인 뷰를 추출하고 서비스 입출력 데이터의 타입에 기반하여 뷰 및 서비스 흐름 분석 방법을 제안한다. 뷰 및 서비스 흐름 분석으로부터 서비스 호출을 위한 사용자 인터페이스 요소가 자동 생성될 수 있다. 제안된 방법은 서비스 조합을 위한 모바일 사용자 인터페이스를 생성할 수 있다. 마지막으로 본 논문에서는 자체 개발된 XForms 브라우저를 이용하여 제안된 방법에 의해 생성된 XForms 페이지가 REST 기반 서비스 접속을 위한 클라이언트로 동작할 수 있음을 보였다.

• 한국정보과학회논문지:소프트웨어및응용
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• 제36권1호
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• pp.1-9
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• 2009

분산된 환경에서 유사한 기능을 제공하는 서비스들의 수가 증가함에 따라, 웹서비스의 신뢰성은 매우 중요한 서비스 선택 요인이 되고 있다. 기업 간 협업과 같은 개방적 비즈니스 모델을 충족시키기 위해, 여러 단위 웹서비스들이 상호 연동하여 상위 수준의 비즈니스 트랜잭션을 형성하는 웹서비스 조합에서 신뢰성의 문제는 더욱 중요해진다. 그러나 단위 웹서비스 각각의 신뢰성이 보장된다고 해도, 조합된 서비스의 신뢰성은 보장되지 않는다. 따라서, 조합된 서비스의 신뢰성에 대한 평가 및 서비스 결정을 위한 방법이 필요하다. 본 논문은 웹서비스의 신뢰성을 평가하기 위한 신뢰도 평가 메트릭스를 정의하고, 이를 통해 조합된 웹 서비스의 신뢰수준을 추측하기 위한 평가 방법을 제안한다. 제안된 신뢰성 평가 모델을 기반으로 웹서비스 조합에서 신뢰할 수 있는 웹서비스 선택을 지원하기 위한 프레임워크를 정의한다. 서비스 사용자의 직관적인 선택이 아니라 정량적인 평가를 통한 선택이 이루어짐으로써, 사용자가 기능적 요구사항뿐만 아니라 품질 요구사항에서도 보다 만족할만한 선택 결과를 얻을 수 있을 것으로 기대한다.

• Journal of Computing Science and Engineering
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• 제6권2호
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• pp.89-104
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• 2012

In dynamic Web service environments, the performance of the Internet is unpredictable; the reliability and effectiveness of remote Web services are also unclear. Therefore, it can hardly be guaranteed that the quality of Web service (QoWS) attributes of Web services do not fluctuate with the dynamic Web service environments. When a composite service is planned in the context of dynamic service environments, there is another aspect which has not been taken into account by existing works, namely, concurrency - the fact that multiple requests to a composite service may arrive at the same time. Considering the dynamics of Web service environments and concurrency of requests, we propose in this paper a service selection scheme which adopts top-k dominating queries to generate a composition solution rather than only select the best composition solution for a given request. The experimental results have investigated the efficiency and effectiveness of our approach and shown that it outperforms baseline and traditional methods for service selection.

• Asia pacific journal of information systems
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• 제13권2호
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• pp.145-170
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• 2003

Open Decision Support System(DSS) is an automated and transparent system that is built to be shared both within and across organizations. The open DSS has been thought to be a set of decision components that are communicating through Web protocols. These characteristics intuitively invite the Web services concepts, which are currently one of the new trends in network-based business services. However, web services still are not active enough to be autonomous, and to provide for composing functionalities. These lead to the motivation on building a sophisticated web service to contain these features and to utilize web services on behalf of the user. This paper aims to propose a new concept of Meta Web Service, a web service-based open DSS. Decision modules in a dynamic and open DSS can be viewed as a web service. The Meta Web Service understands the users problem statement with ontology, performs web service discovery, web service composition, and automatically generates codes for composite web service execution. A prototype of example web service has been developed to show the feasibility of the proposed idea.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권7호
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• pp.1252-1273
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• 2011

In Web Service Composition (WSC) area, services selection aims at selecting an appropriate candidate from a set of functionally-equivalent services to execute the function of each task in an abstract WSC according to their different QoS values. In despite of many related works, few of previous studies consider transactional constraints in QoS-aware WSC, which guarantee reliable execution of Composite Web Service (CWS) that is composed by a number of unpredictable web services. In this paper, we propose a novel global selection-optimal approach in WSC by considering both transactional constraints and end-to-end QoS constraints. With this approach, we firstly identify building rules and the reduction method to build layer-based Directed Acyclic Graph (DAG) model which can model transactional relationships among candidate services. As such, the problem of solving global optimal QoS utility with transactional constraints in WSC can be regarded as a problem of solving single-source shortest path in DAG. After that, we present Graph-building algorithms and an optimal selection algorithm to explain the specific execution procedures. Finally, comprehensive experiments are conducted based on a real-world web service QoS dataset. The experimental results show that our approach has better performance over other competing selection approaches on success ratio and efficiency.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권3호
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• pp.1260-1281
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• 2015

As the number of services available on the Web increases, it is vital to be able to identify which services can be trusted. Since there can be an extremely large number of potential services that offer similar functionality, it is challenging to select the right ones. Service requestors have to decide which services closelysatisfy their needs, and theymust worry about the reliability of the service provider. Although an individual service can be trusted, a composed service is not guaranteed to be trustworthy. In this paper, we present a trust model that supports service discovery and composition based on trustworthiness. We define a method to evaluate trust in order to discover trustworthy services. We also provide a method to perform trust estimation for dynamic service composition, and we present results of two experiments. The proposed model allows for service requestors to obtain the most trustworthy services possible. Our mechanism uses direct and indirect user experience to discover the trustworthiness of the services and service providers. Moreover, composing services based on quantitative trust measurements will allow for consumers to acquire a highly reliable service that meet their quality and functional requirements.

• Journal of Information Processing Systems
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• 제14권4호
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• pp.1010-1032
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• 2018

Recent advances in medical science have made people live longer, which has affected many aspects of life, such as caregiver burden, increasing cost of healthcare, increasing number of disabled and depressive disorder persons, and so on. Researchers are now focused on elderly living assistance services in smart home environments. In recent years, assisted living technologies have rapidly grown due to a faster growing aging society. Many smart devices are now interconnected within the home network environment and such a home setup supports collaborations between those devices based on the Internet of Things (IoT). One of the major challenges in providing elderly living assistance services is to consider each individual's requirements of different needs. In order to solve this, the virtualization of physical things, as well as the collaboration and composition of services provided by these physical things should be considered. In order to meet these challenges, Web of Objects (WoO) focuses on the implementation aspects of IoT to bring the assorted real world objects with the web applications. We proposed a semantic modelling technique for manual and semi-automated service composition. The aim of this work is to propose a framework to enable RESTful web services composition using semantic ontology for elderly living assistance services creation in WoO based smart home environment.