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Pollock

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Pollock

  1. 1. Automatic Generation of Virtual Web Services from Web Sites Yi-Hsuan Lu, Yoojin Hong, Jinesh Varia, Dongwon Lee ACM Symposium on Applied Computing(SAC) 2005 Reporter: Shih-Feng Yang
  2. 2. Outline <ul><li>Introduction </li></ul><ul><li>Background </li></ul><ul><li>Main Ideas </li></ul><ul><li>Conclusion </li></ul>
  3. 3. Introduction <ul><li>Goal </li></ul><ul><ul><li>Propose a methodology that helps to automatically generate Web Services from the FORM-based query interfaces of a web site. </li></ul></ul>
  4. 4. Introduction <ul><li>Example (UniversalBooks) </li></ul><ul><ul><li>A company UniversalBooks is a start-up who aims at building the biggest internet bookstore. </li></ul></ul><ul><ul><li>For each bookstore which has web services, we use it’s own services. </li></ul></ul><ul><ul><li>For each bookstore which has no web service, we build a virtual web service for it. </li></ul></ul><ul><ul><li>Build a broker that provides a universal catalog system based on those web service interfaces. </li></ul></ul>
  5. 5. Introduction <ul><li>Example (UniversalBooks) </li></ul>
  6. 6. Background <ul><li>Web Service </li></ul><ul><ul><li>UDDI (Universal Description, Discovery, and Integration) </li></ul></ul><ul><ul><ul><li>A mechanism for client to find web services. </li></ul></ul></ul><ul><ul><li>WSDL (Web Services Description Language) </li></ul></ul><ul><ul><ul><li>Define services as collections of network endpoints. </li></ul></ul></ul><ul><ul><li>SOAP (Simple Object Access Protocol) </li></ul></ul><ul><ul><ul><li>A message layout specification that defines a uniform way of passing XML-encoded data. </li></ul></ul></ul>
  7. 7. Background <ul><li>Wrapper </li></ul><ul><ul><li>Develop customized grammars to pin-point HTML data to be extracted. </li></ul></ul><ul><ul><li>It is Machine-Learning based approach to learn extraction rules. </li></ul></ul><ul><ul><li>The choice of the wrapper is replaceable. This paper use XWrap. </li></ul></ul>
  8. 8. Background <ul><li>A brief introduction to XWrap </li></ul><ul><ul><li>A XML-based wrapper. </li></ul></ul><ul><ul><li>It is almost a manual tool, you can </li></ul></ul><ul><ul><ul><li>First, input an url. </li></ul></ul></ul><ul><ul><ul><li>Manually select what information you want. </li></ul></ul></ul><ul><ul><ul><li>Automatically generate the Java wrapper codes , Search interface , Web service and WSDL for users. </li></ul></ul></ul><ul><ul><li>XWrap eLite is available now. </li></ul></ul>
  9. 9. Main Ideas <ul><li>Overview </li></ul><ul><ul><li>Wrapper Generator </li></ul></ul><ul><ul><ul><li>Using XWrap. </li></ul></ul></ul><ul><ul><ul><li>use mapping table to keeps mapping track between specific input sequence and wrappers. </li></ul></ul></ul><ul><ul><li>Web Service Generator </li></ul></ul><ul><ul><ul><li>Generate WSDL. </li></ul></ul></ul><ul><ul><li>SOAP translator </li></ul></ul><ul><ul><ul><li>Map SOAP-based XML message into HTTP-based URL message. </li></ul></ul></ul><ul><ul><li>Publish service detail to UDDI </li></ul></ul>
  10. 10. Main Ideas Site which has web services Site which has no web service <ul><li>Overview </li></ul>
  11. 11. Main Ideas <ul><li>Generating Wrappers </li></ul><ul><ul><li>In order to deal with the difference between FORM controls and WSDL schema, we have to handle two type of information: </li></ul></ul><ul><ul><ul><li>String type </li></ul></ul></ul><ul><ul><ul><ul><li>Such as textBox and textArea. </li></ul></ul></ul></ul><ul><ul><ul><li>Enumeration type </li></ul></ul></ul><ul><ul><ul><ul><li>Such as checkBox, Pull-down menu, RadioButton. </li></ul></ul></ul></ul><ul><ul><li>Use XWrap to extract specific data from the returned web pages. </li></ul></ul>
  12. 12. Main Ideas <ul><li>Generating WSDL </li></ul><ul><ul><li><type>: the definition of special data types that are used in WSDL. </li></ul></ul><ul><ul><li><message>: define a service provided by a web service provider and its parameters. </li></ul></ul><ul><ul><ul><li><part>: the definition of the name and data type of parameters. </li></ul></ul></ul><ul><ul><li><portType>: tie a request message and a response message as one operation. </li></ul></ul>
  13. 13. Main Ideas <ul><li>Generating WSDL </li></ul><ul><ul><li>The WSDL Format </li></ul></ul>
  14. 14. Main Ideas <ul><li>Handling SOAP messages (Translator) </li></ul><ul><ul><li>When input the parameters to web service: </li></ul></ul><ul><ul><ul><li>SOAP request -> HTML POST or GET messages </li></ul></ul></ul><ul><ul><li>When the results are returned from service: </li></ul></ul><ul><ul><ul><li>Package results as SOAP response to users. </li></ul></ul></ul><ul><ul><li>When there are multiple wrappers, a mapping table has information to determine which wrapper must be invoked. </li></ul></ul>
  15. 15. Main Ideas <ul><li>Publishing to UDDI </li></ul><ul><ul><li>Four data elements are needed: </li></ul></ul><ul><ul><ul><li>BusinessEntity </li></ul></ul></ul><ul><ul><ul><ul><li>Business description. </li></ul></ul></ul></ul><ul><ul><ul><li>BusinessService </li></ul></ul></ul><ul><ul><ul><ul><li>Actual information about this web service. </li></ul></ul></ul></ul><ul><ul><ul><li>BindingTemplate </li></ul></ul></ul><ul><ul><ul><ul><li>How and where a user can access the web service. </li></ul></ul></ul></ul><ul><ul><ul><li>tModel </li></ul></ul></ul><ul><ul><ul><ul><li>A description and a pointer to external technical specification. </li></ul></ul></ul></ul>
  16. 16. Conclusion <ul><li>A preliminary work on automatically generating web services form FORM-based query interfaces of web sites is presented. </li></ul>

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