Web Services Overview


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  • The first line in the document called The XML declaration must always be included. It defines the XML version of the document. In this case the document conforms to the 1.0 specification of XML. The next line defines the first element of the document (the root element) -- submitter. The next lines define 3 elements of the root (name, company and PIN) and 2 sub-elements of the element (name) – title and phone number. The last line defines the end of the root element -- submitter. All XML elements must have a closing tag. XML tags are case sensitive. The tag <Submitter> is different from the tag <SUBMITTER>. Opening and closing tags must therefore be written with the same case or it will not be a well-formed document and result in an error message.  All XML documents must contain a single tag pair to define the root element . All other elements must be nested within the root element. All elements can have sub-elements. Sub-elements must be correctly nested within their parent element.
  • Web Services Overview

    1. 1. Web Services Overview Ashraf Memon
    2. 2. Overview <ul><li>Service Oriented Architecture </li></ul><ul><li>Web service overview </li></ul><ul><li>Benefits of Web services </li></ul><ul><li>Core technologies: XML, SOAP, WSDL </li></ul>
    3. 3. Service Oriented Architectures <ul><li>essentially a collection of services. </li></ul><ul><li>services communicate with each other. </li></ul>Service Provider Service Consumer Response Request
    4. 4. <ul><li>communication can involve either simple data passing. </li></ul>Service Oriented Architectures Service Provider Service Consumer Response Request Service Provider Procedure/ Workflow Request/Response Service Provider Service Provider Request/Response Request/Response Service Consumer Data Data Data Data <ul><li>could also involve two or more services coordinating some activity. </li></ul>
    5. 5. <ul><li>Service Oriented Architectures are not new </li></ul><ul><li>Previous implementation </li></ul><ul><ul><li>DCOM - Distributed Component Object Model (Microsoft) </li></ul></ul><ul><ul><li>ORB Object Request Brokers based on CORBA Specifications (Java) </li></ul></ul><ul><li>Very Complex </li></ul><ul><ul><li>Non standard interchange format </li></ul></ul><ul><ul><li>Binary information interchange </li></ul></ul><ul><ul><li>Very few tools </li></ul></ul><ul><li>New Implementations </li></ul><ul><ul><li>Web Services </li></ul></ul>Service Oriented Architectures
    6. 6. What are Web Services? <ul><li>A Web Service is programmable application logic accessible using standard Internet protocols. </li></ul>
    7. 8. Web services <ul><li>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. </li></ul>Piece of Code Database Files Tool MS COM C Java Perl Fortran Other tools
    8. 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 Response WSDL SOAP Soap Body Request Header Request Params Body
    9. 10. Benefits of Web Services <ul><li>Facilitates reuse of existing assets </li></ul><ul><li>Lower cost of maintenance </li></ul><ul><li>Reduced impact of change </li></ul><ul><li>Example </li></ul><ul><ul><li>GRIDgrid </li></ul></ul><ul><ul><ul><li>AsciiToMap, XMLToMap, ShapeToMap </li></ul></ul></ul><ul><ul><ul><li>Benefits include availability of useful functionality on the web </li></ul></ul></ul><ul><ul><li>Arcweb Services </li></ul></ul><ul><ul><ul><li>Pool of web services that provide mechanism to access data and GIS functions on demand. </li></ul></ul></ul><ul><ul><ul><li>Benefits include, access to terabytes of spatial data, complex GIS functionality, etc. </li></ul></ul></ul>
    10. 11. XML <ul><li>XML is a programming/formatting language and is basically another version of HTML </li></ul><ul><li>It provides a mechanism to describe structure and organization of Data </li></ul>
    11. 12. XML Example <ul><li><?xml version=“1.0”?> </li></ul><ul><ul><li><Names> <Name>Adam Bosworth</Name> </li></ul></ul><ul><ul><li><Title>General Manager </Title> </li></ul></ul><ul><ul><li><Phone>222-444-666</Phone> </li></ul></ul><ul><ul><li><Company>XYZ Corp.</Company> <PIN>2468</PIN> </li></ul></ul><ul><li></Names> </li></ul>
    12. 13. SOAP <ul><li>SOAP stands for Simple Object Access Protocol . </li></ul><ul><li>SOAP is a simple XML based protocol to let applications exchange information over HTTP. </li></ul><ul><li>SOAP is a protocol for accessing a Web Service. </li></ul>
    13. 14. SOAP Example <ul><li>POST /InStock HTTP/1.1 </li></ul><ul><li>Host: www.stock.org </li></ul><ul><li>Content-Type: application/soap+xml; </li></ul><ul><li>charset=utf-8 </li></ul><ul><li>Content-Length: nnn </li></ul><ul><li><?xml version=&quot;1.0&quot;?> </li></ul><ul><li><soap:Envelope </li></ul><ul><li>xmlns:soap=&quot;http://www.w3.org/2001/12/soap-envelope&quot; soap:encodingStyle=&quot;http://www.w3.org/2001/12/soap-encoding&quot;> <soap:Body </li></ul><ul><li>xmlns:m=&quot;http://www.stock.org/stock&quot;>    </li></ul><ul><li><m:GetStockPrice> </li></ul><ul><li><m:StockName>IBM</m:StockName>      </li></ul><ul><li></m:GetStockPrice> </li></ul><ul><li></soap:Body> </li></ul><ul><li></soap:Envelope> </li></ul>
    14. 15. WSDL <ul><li>WSDL stands for Web Services Description Language </li></ul><ul><li>WSDL (Web Services Description Language) is an XML-based language for describing Web services and how to access them. </li></ul>
    15. 16. WSDL Example <ul><li>URL </li></ul>
    16. 17. Next Chapter <ul><li>Establishing a foundation for web services </li></ul>
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