Framework of Semantic Web Services for Ubiquitous City Management Center. Myungjin Lee, Kyungmin Kim, Sharly Joana Halder, and Wooju Kim*. Dept. of ...
2010 IEEE International Conference on Sensor Networks, Ubiquitous, and Trustworthy Computing
Framework of Semantic Web Services for Ubiquitous City Management Center Myungjin Lee, Kyungmin Kim, Sharly Joana Halder, and Wooju Kim* Dept. of Information and Industrial Engineering, Yonsei University, Seoul, Korea {xml, milren78, sjhalder, wkim}@yonsei.ac.kr development for urban development plans such as HwaSung, PaJu, YangChon, KimPo, YangJu, Incheon and others.
Abstract As adopting ubiquitous technology into civil engineering, new city model is suggested called U-City. This paper proposes the framework of U-City management center to support effective services operation. The aims of the framework are to provide the development and operation environment for U-City services. Basically, these objectives are achieved by adopting the semantic web service technology to the framework. In this paper, OWL-S is mainly conducted to represent the description of U-City services. In addition, this paper insists that fine grained unit services are required to guarantee reusability, compatibility, and scalability of the services on U-City management center. The documentations conducted by OWLS are provided as an example of service descriptions. At the last section, this paper also presents the architecture of U-City management center which enables automatic service discovery, selection, composition and interoperation.
The framework of U-City management center reflects the considerations of “how the huge information from the city integrates and utilizes” to construct and operate U-City effectively. Practically, the information from the city should be organized as an applicable form for information services in a real time. Actually, U-City management center has a core position to achieve successful U-City plans by supplying security and convenience for civilians through public, private, and civil management services based on information communication infra. The services on U-City are categorized into two parts; base service which is applicable for the whole service through the city and specialized service which has a specific purpose for individual functionality of city. However, the definition of the scope and functionality of U-City services is completely different according to the local self governments planning UCity. In consequence, it is necessary to obtain standardization and model for core services which are commonly capable of application by city model.
Keywords - Ubiquitous; Ubiquitous City; Semantic Web Services; U-City Management Center
I.
INTRODUCTION
According to the development of information technology, the new paradigm is advent in computer science called Ubiquitous Computing. In definition, the word "ubiquitous" can be defined as "existing or being everywhere at the same time" [1]. When applying this concept to technology, the term ubiquitous implies that technology is accessible in everywhere, anytime, and whenever. Due to the spread of Ubiquitous technology, the rapid changes are occurring in our society. Besides, the combination of Ubiquitous technology to the civilengineering, the new civil model could be suggested called UCity (Ubiquitous City). Basically, U-City is the city providing an information service to the civilian for their convenience and the effective management of city as well.
Generally, with a service identified by coarse grain, adopting its service to U-City management center is ineffective in terms of reusability. Therefore, it is necessary to consider the services as an abstraction service for service definition and an unit service to reflect the services into U-City management center. Identified unit services comprise a U-City service. Through these, reusability and extensibility of U-City management center framework are guaranteed. XML web services point out a platform independent system supporting cross-functional operation among software. As using XML web service, the platform for U-City services based on SOA undertakes interoperability between services on UCity management center. However, this just ensuring syntactic level interoperability which means it is only possible for service composition in static. Therefore, to secure dynamic service composition, the framework of U-City management center should consider semantics on its service.
The history of U-City in South Korea begins with u-Korea development strategy on June 9, 2004 and currently u-Korea development strategy is on the process all over the regions by Korean government and local self-government. Ministry of Information and Communication and Ministry of Construction and Transportation signed the MOU (Memorandum of Understanding) for the establishment of the development of standardized U-City model in 2006. By the MOU, the related laws and regulations for U-City are revising. In this social mood, U-City plans are playing a key role of national
The SWS (Semantic Web Services) is suggested for intelligence service by adopting the Semantic Web on the Web. The SWS is the technology for the intelligent service discovery, composition, and operation by the description of services using ontology. This technology enables context
* Corresponding author
978-0-7695-4049-8/10 $26.00 © 2010 IEEE DOI 10.1109/SUTC.2010.21
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information to user devices. For example, providing a location based services are capable through the information of devices location such as an airport, theater, baseball stadium.
awareness services which are possible for dynamic discovering and composing service by service context. This research suggests the framework of U-City management center based on SWS technology and the methodology of constructing intelligence services as well. This research would contribute proposing guide line to the design of further U-City framework.
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The paper is structured as follows: Section 2 describes some related works about U-City and the Semantic Web Services. Section 3 presents how to design and how to consist unit services for U-City services. Section 4 shows the framework of U-City management center based on the Semantic Web Services. In Section 5, we conclude and present future works. II.
As a description language for semantic web service, W3C leads the development of SAWSDL (Semantic Annotations Web Service Description Language) [4], OWL-S [5], WSMO (Web Service Modeling Ontology) [6], WSDL-RDF Mapping [7]. Those technologies have a feature of an extension of existed web technology.
RELATED WORK
OWL-S is a markup language for service description. OWL-S generates ontology in terms of ServiceProfile, ServiceModel, and ServiceGrounding. In the part of ServiceProfile, the information of InputType, OutputType, Precondition, and Post-Condition are described. These descriptions let the agents know “what the service is”, when the service is searched from the registry on UDDI by various agents. In the part of ServiceModel, the information of process-flow, composition hierarchy, and process definition are depicted. These parts are used in composition of service. The information of “how access the service” is obtained through the descriptions which are provided on the section of ServiceGrounding.
According to the legislation of U-City in South Korea, UCity is the city providing ubiquitous services such as traffic, environment, welfare and others through the infrastructures of a city i.e. road, bridge, hospital, and others. To construct such a city mentioned above, the city would equip four kinds of functionalities which are the generating, collecting, processing and adopting information. U-City project has a purpose of constructing an information-oriented city which emphasizes its strength of a city. The most of the activities on a city such as traffic, economy, facility management, security management, and others are managed from ubiquitous information technologies. To mange and utilize huge information from an informationoriented city, the development of U-City management center is required.
III.
UNIT SERVICES FOR U-CITY MANAGEMENT CENTER
Ubiquitous environments provide the accessibility of platform independent in everywhere, anytime, and whenever. As adopting this ubiquitous vision to our society, a new city model is revealed called U-City. U-City is a project conversing construction and IT. South Korean government takes advantages of creating new jobs, increasing convenience of life, activating related industry, and constructing comfortable city from U-City project [8]. According to Presidential Commission on Policy Planning in South Korea, U-City project will be promoted from 2009 to 2013 with 490 billion KRW. Through such an intention of South Korean government, currently U-City projects are on the progress in HwaSung, DongTan, and other 36 local self governments. SeJongSi, which is planed city for education and economic, would be involved on U-City project from now on.
Generally, existing city model has several centers according to services. And each center independently executes its operation. However, in the model of U-City, unified services are provided. U-City management center, for example, performs unified services of U-City throughout security, traffic, life, and others based on unified GIS [2]. The platform of UCity management center plays a role of supplying flexible development environments for U-City services. As equipping common components on U-City platform for the development of U-City services, new featured services could be developed easily by using existing common components on U-City platform. Even it has an effect of reducing budget through eliminating unnecessary development cost. The related researches to the SWS (Semantic Web Service) are pointed out. Typically, Web services are only able to compose services in static. For this reason, various attempts have been performed for the dynamic-featured the Web. One of the attempts is to construct intelligence services, as adding context-information to web service [3]. This is achieved by using ontology. Ontology enables intelligent services discovery and composition by keeping context information which indicates the description of service. Following is an example of available services by the SWS. •
Automatic service composition and interoperation: As the availability of automatic selection, composition, and interoperation by ontology which is description of services, it is capable to implement abstracted complicate services.
This chapter suggests the methodology for effective operation of U-City services by analyzing various services from diverse U-Cities. A. A Study for Current U-City Services The components of U-City are categorized into operation center, infra, device. For example, the sensor on city facility such as RFID generates information. This information is collected by a communication infra such as USN and processed from U-City management center to provide adequate services to civilians. Through U-City services, the civilians would have an experience of advanced digitization and user-centered.
Automatic service discover: agent could provide the flexible services based on context-awareness
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Table 1. Supported Services of U-Cities in Korea Business District Hwasung Dongtan Youngin Heungdeok Paju Unjeong Seongnam Pangyo
Happy City
Incheon Songdo
Incheon Cheongra
Sejong-Si
Supported Services
Category
- 5 Services (Phase 1) : CCTV Security, Traffic information, the control service for traffic signal in realtime, Water leakage management, Portal for Dongtan - 7 Services (Phase 2) : Media board and other services - 7 Services : CCTV Security, Traffic information, the service for water supply, Portal, Sewer monitoring, Remote inspection, Media board for bus stop - 48 Services : Total Life-Card, Smart transportation, welfare, U-eco and other services - 13 Services : Weather, Air, Water quality inspection, Water supply management, CCTV security, the control service for traffic signal in real-time, the service for the prevention disaster, Remote education and other services - 49 Services : Traffic service (the control service for traffic signal in real-time, Traffic information, Media board for bus stop etc.), Security service (CCTV), U-eco, the service for facility management (Planning) - 49 Services : Traffic service (the control service for traffic signal in real-time, Traffic information, Media board for bus stop etc.), Security service (CCTV), U-eco, the service for facility management (Planning) - 13 Main Services : the control service for traffic signal in real-time, public transportation information, Unattended enforcement of illegal parking, U-security, U-eco, the management of water supply, U-facility, media board, and other services - 15 Base Services : Traffic, Security, Environment, Facility management, Portal etc. - 1 specilized service
Information acquisition
Information process
Information association
Table 2. Unit Services List Service Requestor Unit Service Type Temperature monitoring Continuous service CCTV Query based Center service Reporting Query based Center service Measuring the amount of Query based traffic Analyzing traffic Query based Center situation Related Transfer Query based Organization image data Voice broadcasting Query based service Information service notifying Query based traffic situation
Input Source Sensor Sensor Center Center Device Center Center
Center
definition for identification of standardized services are required. Deciding the scope of services is an important consideration of identification of services. What it means by that with a fine grained services, it has potential risk to make services process complicate. However, if an identified service is too coarse grained, the reusability of services decreases as a component. In the case of U-City project from South Korea, the matters of the highest priority are reusability, extensionality, and compatibility of services because U-City projects are performed country-widely. For this reason, the unit services for U-City services pursue fine grained services design to avoid the duplicated development of services.
According to Korean Agency for Digital Opportunity and Promotion, the concept of U-City services is defined as “unified and intelligence content set to maximize ubiquitous technology such as context awareness and information processing, information infra like sensors and electronic tags , and city components, for example, city infra, human, and natural environment” [9]. With above definition, U-City services are regarded as the services which provide relative information and content to human i.e. whenever and anyplace. Such U-City services are differently defined according to the cities performing U-City projects.
The association and application of unit services are a key factor to construct successful U-City management center. For this, U-City management center would implement SOA (Service Oriented Architecture) to guarantee an intimate connection among unit services.
Generally, U-City services are separated into two kinds of service which are base services for public purpose and specialized services having specific purpose on its adoption. Basically, base services provide common functionality which used to be possible in existing city model. On the other hand, specialized services supply specific services reflecting the strength of city such as education, finance, and others. Following Table 1 indicates the service list which will be implemented to cities respectively.
B. The Methodology for Unit Services of Ubiquitous City This chapter suggests the methodology for utilizing U-City services effectively. In order to achieve this objective, as a first sequence, U-City services would be separated into several unit services, and then provides how those services are composed efficiently.
Table 1 indicates that the scope of services and the standard for categorization are different according to the cities. For the reason of the differences of service scope, every U-City management system on each city has an independent platform. As a consequence, duplicated investigation occurs in view of South Korean government. The reason, why such a problem is happening, is that any of discussion for the scope of services, the functionality of services, and the performance of services are not exchanged between local self-governments before embarking upon U-City project. In order to solve such a problem, the development of standardized platform and the
As this paper mentioned previous section, the differences of the standard for service scope causes reducing interoperability of U-City management center. In addition, a service would be identified according to the behavior of user, location where service perform, and the target of a service. Therefore, defining detailed unit services is required for the flexibility, compatibility and scalability. In order to extract detailed unit services, unit services for this paper are derived from the common services by U-City services indicated in other U-City projects such as Incheon
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ChengRa U-City project and SaeJong U-City project in South Korea. To defining sub service in this paper, the service is reconstructed by extracting use case from the existing U-City services based on [10] through the dividing and combining of use case. The reconstructed use cases are identified as a service. Table 2 indicates the parts of unit services. The categorized items on Table 2 point out the purpose of a unit services. Two types of service are noted which are query based service and continuous service. For example, the service called from sensors is a continuous service because U-City management center always keeps the information.
Figure 1. Semantic Web Services
U-City services can be reconfigured as a combination of services. In the case of services deployed in U-City management center as a form of unit services, dynamic combination of services according to a situation can be achieved. As applying the structure of service configurations above into U-City management center, personalized services could be generated by adopting context-awareness technology [11]. In addition, intelligent personalized services could be achieved by the reasoning into ontology containing context information of a service. When designing U-City management center, there are few considerations to construct such forms of services. The first is to enable context-awareness services for supplying appropriate services to user. As mentioned earlier, if it is possible to collect knowledge from the context information of user such as a pattern of user’s behavior, the location of accessed device and other information, user centered services could be implemented. In addition, as applying semantic technology like reasoning to context-awareness technology, an intelligence service is capable [12, 13]. The second is service-oriented architecture. SOA is the architecture of enabling flexible utilization of service without considerations of interfaces of systems, communication networks, and other system architectures. The interoperability between U-City management centers located in other cities could be obtained by implementing SOA. The third is the Semantic Web Service. The SWS is an effort to overcome the limitations of existing web service technology which are static and machine ununderstandable. The SWS permits automatic service selection and composition in real-time to the system. As a result, an elastic service creation could be accomplished by applying SWS to a U-City management center.
Figure 2. Flow Chart of Unit Services for Fire Suppression
Intelligent services are provided by automatic services discover, selection, and composition through semantic web services technology. Providing flexible services could be available by adopting SWS into U-City management center. Of the technologies supporting semantic web service, this paper adopts OWL-S to construct framework. OWL-S is a semantic web services language for ontology. Automatic service discovery, composition, and execution would be performed by interpreting the services description of ontology. OWL-S documentation is conducted by representing several sections which are ServiceProfile, ServiceModel, and ServiceGrounding. Fig. 2 represents the relationship between unit services to describe the semantic web services framework. Unit services are categorized into three domains which are information acquisition, information processing, and information association. The boxes included in each domain indicate unit services. Fire monitoring service has a following sequence. The transferred images from CCTV are stored to UCity management center. If operator judges an event as an emergency situation, the service of fire suppression is called through the association of related organization system. Alternatively, a fire monitoring service could issue a fire event by analyzing data from various sensors. As representing above, a service could be generated by composing unit services according to a situation. To maximize the feature above, the methodology for dynamic service combination is required.
All three technologies mentioned above are researched through academic-industrial research institutions as elements for the framework of U-City management center. The next section suggests the methodology of adopting SWS into U-City management center and a framework which enables intelligent agent as offering dynamic services. IV.
FRAMEWORK FOR SEMANTIC WEB SERVICES OF U-CITY
Web services technology enables distributed computing by using XML technology. However, an implemented system by web service technologies is static and machine ununderstandable. For this reasons, Semantic Web Service technology has been discussed to create dynamic and machine understandable system. However, Fig. 1 points out the semantic web in terms of information-retrieval model [14].
Fig. 3 describes a sensor service which is one of the unit services accounted on Fig. 2. Information acquisition is performed by various sensors on U-City, and then specific
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Figure 3. Service Description of Sensor Unit Service
Figure 4. Service Profile of Sensor Unit Service
Figure 6. Service Grounding of Sensor Unit Service
Figure 5. Service Process of Sensor Unit Service
service could be commenced by collected information from diverse sensors. The “presents” property represents a connection to the ServiceProfile. The “describedBy” property is for ServiceProcess and the “ServiceGrounding” is linked by the “supports” property. Fig. 4 indicates a part of information from ServiceProfile section describing unit service for a sensor. Typically, in the section of ServiceProfile, the information of service providers, service functional characteristics, and general characteristics are described. And the description of service functional characteristics includes the information of InputType, OutputType, Precondition, and Effect. The domain model shown from Fig. 4 is represented by OntoSensor [15] which is based on the model of ISO (International Organization for Standardization) and OGC (The Open Geospatial Consortium). The unit service for a sensor only has output related data model because the service is categorized into continuous services. Fig. 5 points out a part of service descriptions on the section of ServiceProcess. Process model in OWL-S consists of atomic process and composite process. Atomic process is the process of which an input results in an output. On the other hand, composite process is the process which calls a service by the combination of atomic process. Fig. 5 represents SensorProcess consists of atomic processes and accounts ResponseModel result from atomic processes. Fig. 6 indicates a part of service information about ServiceGrounding. In ServiceGrounding section, OWL-S describes the information on how the service is accessed. Such information
Figure 7. Composition Process of Unit Services
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Figure 8. Framework of Semantic Web Services for U-City
of protocol, serialization, and service URL is conducted on ServiceGrounding section to enable service access. Fig. 6 is an example for ServiceGrounding section. Fig. 6 represents the technical knowledge to implement SensorService. Unit services would be more detailed than an above example in the practical platform of U-City management center because huge numbers of sensors are embedded on U-City and data types from sensors extremely diverse. Fig. 7 indicates a composed service represented on Fig. 2.
services conceptual models and services process models [16]. The functionality of inference is a key feature of the semantic web services. The validations or activities of service discovery, service selection, and interoperation are achieved by inference. At the last, service registration is a process to register a service which is newly found from UDDI or is re-constructed by unit services. Service managements involve the functionality of service publication, service composition, service discovery, and service deployment to provide management environment of service.
The unit service for fire monitoring is commenced in the case of which the difference of temperature is more than 10 degree. If fire monitoring service is activated, service process pursues following sequence. The unit service storing the sensor data is executed and then the unit service which monitors fire is performed. After that fire alarm service is activated by a result of previous service. This section deals with OWL-S documentation for fire monitoring service. An agent could have features of automatic service discovery, selection, and composition from adopting semantic web technology to a platform which is applying OWL-S in this paper. As a consequence, a platform would provide flexible service based on the context of user. This paper suggests the platform of UCity management center based on the semantic web services. The architecture of the platform is showing in Fig. 8.
V.
CONCLUSION AND FUTURE WORKS
As developing ubiquitous technology and IT technology, supplying IT technology to human in everywhere, anytime, and whenever is available. As consolidating this vision of ubiquitous into civil engineering, the new city model called UCity is revealed. Currently, the term of U-City is popularized in South Korea and practically U-City projects are on the process from local self governments in South Korea. This paper suggests the platform and the methodology for effective design and operation of services for U-City management center. Most of previous researches is inadequate to construct U-City management center, because typically, the researches related to U-City discussed abstract-leveled services identification and only researched for the interoperability between platforms. This paper insists that services of U-City would consist of fine-grained unit services which are identified in terms of a context of services. In this paper, unit services are extracted by use cases iteratively to achieve above objective. The reusability of services is guaranteed by providing a service through the combination of extracted unit services.
The architecture of U-City consists of two parts which are ontology and platform to support ontology. As this paper mentioned, service ontology has operation with the information of service models, service processes, and service constraints. Core services and service managements comprise the framework for the semantic web services. Core services have operations of mediating service and matchmaking service. Therefore core services have functionalities of inference and registration for a service. The mediation of services has purpose of neutralization of differences in data types and transferred messages which could result from service composition. Matchmaker has a role of service selection to compose approximate services according to the circumstance of user. There are various researches for service matching on OWL-S. Basically it is performed by the comparison of
The Semantic Web technology is adapted to U-City management center to enable dynamic composition of services according to the circumstance of user. Existing web technology such as BPEL (Business Process Execution Language) is only possible to represent business process in static. However, dynamic service composition is required for U-City management center because U-City services are generated by
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huge number of combinations from unit services on city. In order to support dynamic and flexible services based on context-awareness technology, this paper suggests the Semantic Web Services platform with applying OWL-S. The suggested platform consists of service ontology and service platform. Generally, service ontology takes part of describing service in terms of context. Therefore this platform plays a role of service operation for instance, service discovery, selection, composition, and interoperation.
[5]
[6]
[7] [8] [9]
All required unit services for U-City management center would be extracted as a future work through analyzing common services provided by U-City management center. In addition, U-City management center would be testified by implementing the developed components from extracted unit services.
[10]
[11] [12]
ACKNOWLEDGMENT This research was financially supported by the Ministry of Knowledge Economy (MKE) and Korea Industrial Technology Foundation (KOTEF) through the Human Resource Training Project for Strategic Technology.
[13]
[14]
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