• The KIPS Transactions:PartA
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• v.17A no.2
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• pp.93-102
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• 2010

There are many complicated situations which could be occurred in users' surroundings, so it is required to develop automation services to provide users with appropriate services in ubiquitous computing environments. However, most of the current context-aware workflow systems express context-aware services only with a single workflow. Therefore, they have difficulties in providing users with various and composite services by combining different workflows. In this paper we propose a CAWL-based context-aware workflow system, where CAWL is a context-aware workflow language to express a composite workflow model by describing individual service workflows. The proposed system can provide users with various composite workflow services based on a service scenario, which is described with CAWL. And by reusing a number of single workflows to construct composite workflow services, it is possible to save time and effort to develop context-aware workflows.

• Journal of KIISE:Software and Applications
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• v.34 no.5
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• pp.431-446
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• 2007

Executable composite Web services are selected by binding a given abstract workflow with the specific Web services that satisfy given QoS requirements. Considering the rapidly increasing number of Web services and their highly dynamic QoS environment, the fast selection of composite services is important. This paper presents a method for quality driven comosite Web services selection based on a workflow partition strategy. The proposed method partitions an abstract workflow into two sub-workflows to decrease the number of candidate services that should be considered. The QoS requirement is also decomposed for each partitioned workflow. Since the decomposition of a QoS requirement is based on heuristics, the selection might fail to find composite Web services. To avoid such a failure, the tightness of a QoS requirement is defined and a workflow is determined to be partitioned according to the tightness. A mixed integer linear programming is utilized for the efficient service selection. Experimental results show that the success rate of partitioning is above 99%. Particularly, the proposed method performs faster and selects composite services whose qualities are not significantly different (less than 5%) from the optimal one.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.2
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• pp.144-156
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• 2010

With the wide spread of Web services in various fields, there is a growing interest in building a composite Web service, however, it is very difficult for ordinary users to specify how to compose services. Therefore, a convenient interface for generating and invoking composite Web services are required. This paper proposes a natural language interface to invoke services. The proposed interface provides a way to describe users' requests for composite Web Services in a natural language. A user with no technical knowledge about Web services can describe requests for composite Web services through the proposed interface. The proposed method extracts a complex workflow and finds appropriate Web services from the requests. Experimental results show that the proposed method extracts a sophisticated workflow from complex sentences with many phrases and control constructs.

• Journal of the Korea Society for Simulation
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• v.16 no.4
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• pp.77-86
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• 2007

Web services are considered as the critical component in the business plans of corporations as they offers the potential for creating highly dynamic and versatile distributed applications that span across business boundaries. Web Service Orchestration studies composition of already-existing web services to create new value-added services. The composite web services could be executed in a centralized or peer-to-peer(P2P) orchestration model. Compared with centralized-orchestration model, the P2P-based orchestration model provides better scalability, reliability, and performance for the overall services. However, recent P2P-orchestration solutions have limitation in supporting complex workflow patterns. Therefore, they could not effectively handle sophisticated business workflow, which contains complex workflow patterns. In this paper, we propose the WORKGLOW system, which can deal with complex workflow patterns while it is able to perform composite services in P2P orchestration manner. Comparing with centralized orchestration systems, the WORKGLOW brings up more business logic advantages, better performance, and higher flexibility with only a little overhead.

• Journal of Internet Computing and Services
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• v.10 no.6
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• pp.145-157
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• 2009

In recent years, there have been several researches applying workflow technologies for service automation on ubiquitous computing environments. However, most context-aware workflow languages have difficulties in supporting composite workflows composed of single workflows, because these languages are still in its early stage and they only provide single workflow services to their users. This paper introduces CAWL, which is a context-aware workflow language. CAWL is for describing individual service workflows to make integrated service workflows. By using CAWL, service developers are able to reuse existing workflows to develop new context-aware workflow services. Therefore, development efforts and time can be saved and workflow resusability also increased. CAWL is expected to make it easy to develop applications related to context-aware workflow services on ubiquitous computing environments.

• IE interfaces
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• v.19 no.3
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• pp.190-201
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• 2006

With the rapid growth in the demand and supply of web service, the search for superior services has become a prominent issue. Furthermore, much emphasis and attention are being placed on composite web services, where individual services are combined together to form a single workflow to satisfy the demand of the customers. In today's era of excessive expansion of web services, this study intends to propose the execution plan architecture for composite web services to accomplish the following three goals. The first goal is to derive a feasible plan which maximize user satisfaction for composite web services by implementing an execution plan architecture that reflects the Quality of Service criteria. Secondly, this study also aims at analyzing and selecting the indexes that adequately reflects its quality and its nonfunctional property. Finally, this study intends to apply the concept of constraint satisfaction problem and heuristics to reduce the execution duration of the process.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11b
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• pp.13-15
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• 2005

웹 서비스는 서비스 지향 컴퓨팅 환경으로의 변화를 주도하는 기술로써 많은 각광을 받고 있다. 본 논문에서는 사용자가요구하는 품질의 서비스를 선택할 수 있는 방법을 제안한다. 제안된 방법은 워크플로우를 분할하는 휴리스틱에 기반하여 기존의 LP(Linear Programming) 기반의 서비스 선택 알고리즘의 수행시간을 단축한다.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06c
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• pp.7-9
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• 2006

본 논문은 워크플로우 분할에 기반하여 복합 웹 서비스를 빠르게 선택하는 방법을 제안한다. 제안된 방법은 QoS 요구사항의 제약정도 계산, 워크플로우 분할, QoS 요구사항 분해, 그리고 서비스 선택의 네 단계로 구성된다. 특히 QoS 요구사항의 분해과정이 휴리스틱에 기반하기 때문에 워크플로우 분할 시 QoS 요구사항을 만족하는 서비스를 찾지 못할 가능성이 있다. 제안된 방법은 분할에 따른 서비스 선택 실패를 줄이기 위해 주어진 QoS 요구사항의 제약정도를 계산하여 워크플로우의 분할 여부를 판단한다. 실험 결과 제안된 방법은 분할 속도, 성공률, 품질 면에서 우수한 성능을 보였다.