Web Services Overview Ashraf Memon

2 Overview Service Oriented Architecture Web service overview Benefits of Web services Core technologies: XML, SOAP, WSDL

3 Service Oriented Architectures essentially a collection of services. services communicate with each other. Service Provider Service Consumer Response Request

4 communication can involve either simple data passing. Service Oriented Architectures Service Provider Service Consumer Response Request Service Provider Procedure/ Workflow Request/Response Service Provider Service Provider Request/Response Service Consumer Data could also involve two or more services coordinating some activity.

5 Service Oriented Architectures are not new Previous implementation –DCOM - Distributed Component Object Model (Microsoft) –ORB Object Request Brokers based on CORBA Specifications (Java) Very Complex –Non standard interchange format –Binary information interchange –Very few tools New Implementations –Web Services Service Oriented Architectures

6 What are Web Services? A Web Service is programmable application logic accessible using standard Internet protocols.

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8 Web services Piece of Code Database Files Tool MS COM C Java Perl Fortran Other tools Web service is any piece of code that can be made available over the Internet, so that other applications can invoke it and utilize its functionality.

9 What are Web Services? …. Piece of Code Deployment Script Soap Server Service Provider Code Service Description Soap Client API Service Client SOAP over HTTP Service Description Soap Listener Header Body Service Response Soap Body Request Header Request Params Body WSD L SOAP

10 Benefits of Web Services Facilitates reuse of existing assets Lower cost of maintenance Reduced impact of change Example –GRIDgrid AsciiToMap, XMLToMap, ShapeToMap Benefits include availability of useful functionality on the web –Arcweb Services Pool of web services that provide mechanism to access data and GIS functions on demand. Benefits include, access to terabytes of spatial data, complex GIS functionality, etc.

11 XML XML is a programming/formatting language and is basically another version of HTML It provides a mechanism to describe structure and organization of Data

12 XML Example Adam Bosworth General Manager XYZ Corp. 2468

13 SOAP SOAP stands for Simple Object Access Protocol. SOAP is a simple XML based protocol to let applications exchange information over HTTP. SOAP is a protocol for accessing a Web Service.

14 SOAP Example POST /InStock HTTP/1.1 Host: Content-Type: application/soap+xml; charset=utf-8 Content-Length: nnn <soap:Envelope xmlns:soap=" soap:encodingStyle=" <soap:Body xmlns:m=" IBM

15 WSDL WSDL stands for Web Services Description Language WSDL (Web Services Description Language) is an XML- based language for describing Web services and how to access them.

16 WSDL Example URL

17 Next Chapter Establishing a foundation for web services