I5-5 - Sedma Nacionalna Konferencija so Me|unarodno U~estvo ETAI'2005 Seventh National Conference with International Participation ETAI'2005 Ohrid

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WEB SERVICES FOR DISTRIBUTED SEARCH AND RETRIEVAL Elena Ivanova 1 1 Institute of Computer and Communication Systems – Bulgarian Academy of Sciences, Sofia, Bulgaria, [email protected] Abstract – Web Service technologies are applied to obtain selective search and retrieval in distributed databases. Three Web Service architectures for distributed search are proposed and implemented. Software application with this functionality is described. Keywords – Database, Distributed Search, Service oriented architecture, SOAP, WSDL 1. INTRODUCTION The paper aims to present how the operations “Searching” and “Retrieval” in distributed database is developed as Web Services. It is naturally to use Web Service technologies for working with distributed databases, having in mind that they have become the base for distributed and decentralized systems for some time now. Web services provide a standard means of interoperating between different software applications, running on a variety of platforms and/or frameworks [1]. They are software programs that use XML as an open standard for application-to- application data exchange via common Internet protocols. A Web Service communicates over a network to supply a specific set of operations that other applications can invoke [2], [3], using open standards: ± XML (Extensible Markup Language) - used in the Web Services architecture as the format for transferring information/data between different programming modules and between incompatible systems. ± WSDL (Web Services Definition Language) - 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. ± UDDI (Universal Description, Discovery, and Integration) - XML-based lookup service for locating Web Services in an Internet scenario. SOAP (Simple Object Access Protocol) - a lightweight, XML-based messaging protocol that contains an envelope, header, and body, designed to exchange information in a decentralized, distributed environment [1]. It is the channel used for communication between a Web Services provider application and a client application. The Web Service framework was defined, standardized and supported very fast [14]. It became widely applicable [16-17]. Because of their interoperability and standardized data exchange, Web Service technologies can be very useful and powerful when it has to operate with distributed heterogeneous databases. 2. CHARACTERISTIC AND REPRESENTATION OF A SERVICE Let’s take a brief look at the evolution of web based applications that propose e-services [4]. In the beginning such applications are designed by static web pages based on data centric Client/Server architecture – the web server delivers a web page when it is queried by the client application (web browser). Deployment of the server-side programming languages extends that architecture by including of dynamic program modules that process the users’ queries and manipulate information on
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This note was uploaded on 02/18/2010 for the course ITK ETF113L07 taught by Professor Popovskiborislav during the Spring '10 term at Pacific.

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I5-5 - Sedma Nacionalna Konferencija so Me|unarodno U~estvo ETAI'2005 Seventh National Conference with International Participation ETAI'2005 Ohrid

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