Proceedings of the. 1 INFORMATION TECHNOLOGIES IN E-GOVERNMENT SOLUTIONS Elena Ivanova, Todor Stoilov Sofia 1113, Acad. G. Bonchev STR, bl.2, Institute of Computer and Communication Systems, e_ivanova@hsh.iccs.bas.bg todor@hsi.iccs.bas.bg Bulgaria Abstract Interoperability is the primary objective of all e-government activities. Interoperability has to be considered in two aspects technological interoperability and semantic interoperability. The paper deals with information technologies for e- Government solutions providing technological and semantic interoperability. Key words: Semantic Interoperability, Technological Interoperability, Web Services. 1. INTRODUCTION E-Government services have a special place in the field of e-services applications, because they address a wide audience of customers. This audience has different level of computer skills, possess various types of requirements and expect partly or full level of services. These considerations insist from the e-government services to be more robust from functional point of view and to operate in indeterminist environments in comparison with any other e-services. Interoperability is the primary objective of all e-government activities. This fact involves in compiling a set of guidelines, standards and solutions that, when adopted by the individual administrations, will provide and maximize interoperability. Interoperability has to be considered in two aspects technological interoperability and semantic interoperability. Technological interoperability concerns the ability of integrate a variety of services and information resources into a common virtual system. Semantic interoperability refers to semantic categorization of services and to service composition. E-Government framework involves in combining multiple innovative technologies. The paper discusses the prospective set of information technologies, which can be implemented in e- Government solutions providing technological and semantic interoperability. 2. ARCHITECTURE FOR E-GOVERNMENT APPLICATIONS E-Government is a common, distributed virtual environment for administrative services. These services are implemented by different software applications, running on a variety of platforms and/or frameworks. Service Oriented Architecture (SOA) addresses the problem of software complexity. SOA is architecture consisted of components and interconnections that stress interoperability and location transparency [1]. These are provided by the base features of SOA: a standard way for communication, a uniform data representation and exchange mechanism, a standard meta language to describe the services offered a mechanism to register and locate services-based applications. SOA can also be considered as a set of interacting services. SOA is considered to be the right environment for designing e-government services.
2 Proceedings of the. 3. TECHNOLOGICAL INTEROPERABILITY Technological interoperability refers to ability of integrate a variety of services and information resources into a common virtual system. In particular, it means that agent in the system may use different network support wired network, WAP devices, or other support. Web Service technologies provides good means of such kind of integration. They considered being the best way of implementing SOA [2]. The Web service refers to a service over a computer network that resides in a specific environment. The environment provides means to describe and to discover the services, interact with other services to provide integration of functionalities. The Web service as a programmable application logic is accessible using standard Internet protocols. They are software programs that use XML as an open standard for application-to-application data exchange, SOAP as communication protocol, WSDL for describing services and UDDI for register and locate services. Web services combine the best aspects of component-based development and the web. Like components, Web services represent functionalities that can be easily reused without knowing how the service is implemented. Practically Web Services have emerged as a powerful mechanism for integrating information resources. The Web service framework is being defined, standardized and supported by the industry at a record pace. It receives broad industry acceptance and standard compliance, which makes it widely applicable [3-6]. The XML formats of data presentation are assumed as natural extension of the HTML coding [7]. Due to its inner free tag definition structure, XML technology is widely applied in the Web for data presentation and data serialization. The communication and messaging between XML results sets is performed by the protocol SOAP. SOAP (Simple Object Access Protocol) is a lightweight, XML-based messaging protocol that contains an envelope, header, and body (fig.1), designed to exchange information in a decentralized, distributed environment [8]. It is the channel used for communication between a Web Services provider application and a client application. <SOAP-ENV:Envelope xmlns="http://schemas.xmlsoap.org/soap/envelope/"> < SOAP-ENV:Header> </ SOAP-ENV:Header> < SOAP-ENV:Body> </ SOAP-ENV:Body> definitions types message porttype binding service fig1. The SOAP Envelope Fig.2. Structure of a WSDL document The networked Web services are described by WSDL language [8]. WSDL (Web Services Definition Language) is a XML-based language, used to describe Web Services. A WSDL document describes the functionality of proposed Web Service, how it communicates and where it is accessible. It consists of the following pieces of data [9]: Interface information describing all publicly available functions; Data type information for all message requests and message responses;
Proceedings of the. 3 Binding information about the transport protocol to be used; Address information for locating the specified service. WSDL is platform- and language-independent as the rest Web Service technologies [9]. The root element of a WSDL document is < definitions>. Its main parts are listed below [11] (see fig.2): <porttype> - The operations performed by the Web Service; <message> - The messages used by the Web Service; <types> - The data types used by the Web Service; <binding> - The communication protocols used by the Web Service. The UDDI standard is developed to design a structured public registry containing information about the info services and their functionalities. UDDI registry can be either public or private. UDDI (Universal Description Discovery and Integration) is an XML-based Web Services standard [8] with information organized as follows (fig.3): Business Entity - information about a business including its name, a short description, and some basic contact information. It is the root element; Business Service - a list of business services offered by the business entity; Binding Templates - a list of binding templates providing information on localization of the service and the ways of using it; Service Types - define an abstract service. Several businesses can offer similar services all supporting the same service interface. The construction describing a service type is called and specifies its name, the name of organization offering the service, a list of categories, and pointers to technical specifications. Business Entity Business Service Binding Template Binding Template Fig.3. Main UDDI elements 4. SEMANTIC INTEROPERABILITY As it was mentioned above, semantic interoperability concerns semantic categorization of services and the definition of data structures that could be standardized and exchanged between governmental agencies. The semantic support of operations aids service composition into a workflow that is executed sequentially as a hole. Having in mind the rising number of available services and the dynamic nature of the Web, it is necessary to automate the process of combining services. WSDL standard for describing services provides only technical interoperability between services. In order to compose services in a workflow it is needed interoperability on a semantic level. OWL (Web Ontology Language) is an attempt to standardize how Web Services are described semantically [10]. Ontology explicitly represents the meaning of terms or concepts and their relationships (e.g. taxonomy). Ontologies can be specified in a machine readable language like OWL to be further processed by different type of software applications. OWL is a recent standard from [8] and is based on RDF (Resource Description Framework) and RDFS (RDF Schema)
4 Proceedings of the. themselves based on XML. OWL allows representing complex relationships and constraints in ontologies (e.g. exclusions, dependencies, etc) and is made of three sub- of increasing complexity: OWL Lite, OWL DL and OWL Full. OWL can be considered as a semantic layer on top of WSDL that maps operation parameters to semantics defined in ontologies. Once described semantically, single services may be composed into a complex service (workflow). The business workflow area is in constant evolution and there is not yet a single emerging set of standard technologies. A first analysis shows a reference model made of at least four functional blocks: modeling methodologies, choreography, orchestration, graphical notations that can be used for choreography and/or orchestration (fig.4). UMM Modelling methodologies Graphical notation BPMN UML WS-CDL WSCI WSCL Choreography (non executable) BPML BPEL WSFL Orchestration (executable) Fig.4. Business workflow standards The following table lists some of the workflow technologies. Standard /Source/ BPEL / OASIS / BPML /BPMI/ BPMN /BPMI/ /ebxml/ UML /OMG/ UMM /UN/CEFACT/ Name&Short Explanation URL Business Process Execution Language - an XML language for www.oasis-open.org the description of Web Services compositions as part of a business process definition. Business Process Modeling Language - a textual service-oriented www.bpmi.org process modelling language Business Process Modeling Notation - a graphical notation www.bpmi.org language for defining internal and external business processes, with a formal mechanism to generate executable business processes using an orchestration language Business Process Specification Schema - provides a standard www.ebxml.org framework (language) for business process specification. Unified Modeling Language - a graphical notation language for www.omg.org visualizing, specifying, constructing and documenting artifacts of a software-intensive system UN/CEFACT Modeling Methodology - describes a method and www.unece.org/cefact supporting components to capture business process knowledge, independently of the underlying implemented technology so that business acumen is retained and usable over generations of implemented technologies.
Proceedings of the. 5 WSCI /BEA, Intalio, SAP, Sun/ WSCL /HP/ WSFL /IBM/ WS-CDL /W3C/ Web Service Choreography Interface - describes a method and www.w3.org/tr/wsci/ supporting components to capture business process knowledge, independently of the underlying implemented technology so that business acumen is retained and usable over generations of implemented technologies. Web Services Conversation Language - provides an XML www.wscl.org/ schema for defining legal sequences of documents that webservices can exchange. Web Services Flow Language - an XML language for the www-3.ibm.com/ description of Web Services compositions as part of a business process definition. Choreography Description Language - an XML-based www.w3.org choreography language that allows defining from a global viewpoint the observable behavior of different business entities. 5. CONCLUSIONS Service Oriented Architecture, implemented by the Web Service technologies SOAP, WSDL and UDDI, is considered to be appropriate solution for developing common e-government environment. It functionality defines the best way to provide technical interoperability between various range of services, implemented by different software applications, running on a variety of platforms and/or frameworks. In order to compose services in a workflow it is needed interoperability on a semantic level. OWL technology aids the semantic interoperability between services. The paper described a set of information standards which cope the variety of the requirements towards services, the heterogeneous technological support and the different type of customers. The developments in the e-government domain prove the necessity of utilization of different software technologies but firmly coordinated by prospective standards. Thus the problem of coordinating the mess of solution is solved successfully and the business workflow is coped with the administrative e-government applications and services. REFERENCES 1. http://www.developer.com/ 2. Channabasavaiah, K., K.Holley, M. Edward and Jr. Tuggle (2003). Migrating to a serviceoriented architecture, Part 1, www-106.ibm.com 3. Иванова Зл., К.Стоилова, Т. Стоилов. Системно алгоритмични модели на информационните услуги в Интернет. Сп. Автоматика и информатика, N3/03, 13-18. 4. Trichkov Kr. Application of Z39.50 protocol for Global Network Services. Proc. Project Management Meeting, Regnet, EC-IST-200026336, 24-26 June 2002, 34-41. 5. Кемалов А.П. Графична и числена оценка на QoS рутиране в LAN/VPN. Нац. Конференция Автоматика и Информатика, София,1999. 6. Tsenov M. Implementation of SOAP/WSDL web services with open code, Int.Conf. Automatics and informatics, vol.1, Bulgaria, Sofia, October, 6-8, 2003, 83-85. 7. DuCharme B. XML, the annotated specification, Prentice Hall, NJ, 1999 8. http://www.w3.org/tr/ 9. Cerami E. Web Services Essentials, O Reilly, 2002 10. Dean, M. (ed). OWL-S: Semantic Markup for Web Services. Version 1.0, 2004. This research is partly supported by the National Scientific Fund of Bulgaria, project ВУ-966, 2005.