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Chapter 13 XML

Chapter 13 XML. Concept of XML Simple Example of XML XML vs. HTML in Syntax XML Structure DTD and CDATA Sections Concept of SAX Processing Download and Configure SAXP Pack Example of SAX Parser in Java with XML Concept of DOM Processing Building a DOM Tree from a XML File

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Chapter 13 XML

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  1. Chapter 13 XML • Concept of XML • Simple Example of XML • XML vs. HTML in Syntax • XML Structure • DTD and CDATA Sections • Concept of SAX Processing • Download and Configure SAXP Pack • Example of SAX Parser in Java with XML • Concept of DOM Processing • Building a DOM Tree from a XML File • Concept of XSLT

  2. Chapter 13 XML (continue) • Examples of Stylesheets • Concept of SOAP • Examples of Using SOAP Servers with Messages • SOAP API and SOAP Server Tomcat • Configuring SOAP API and SOAP Server Tomcat • Example of Using SOAP API with Tomcat • In-Class Exercises and Lab Assignment

  3. Concept of XML • What is XML? - is eXtensible Markup Language - Easily modifying, changing, or adding data features due to its modular structure - is actually “meta-language” • Why XML? - Simplify documents communication across different applications and languages - Customize data storage, arrangement, and organization - Easily validating, integrating, and error detecting within an application

  4. Concept of XML(continue) - Data in stylesheet can be customized to any output desired - Any type of data can be expressed as an XML document. XML provides rules to describe data

  5. Simple Example of XML <?xml version=“1.0”?> <!– xml document declaration --> <SHOWS> <PERFORMANCE> <TITLE>Fairy Princess</TITLE> <AUTHOR/> <DESCRIPTION> Scratch sound with emphasis on color, texture. </DESCRIPTION> <DATE status=“canceled”>04/16/2002</DATE> </PERFORMANCE> </SHOWS> <!-- Note: <AUTHOR/> is an empty tag without data -->

  6. Simple Example of XML (continue) • Execution result in Netscape 6.0: Fairy Princess Scratch sound with emphasis on color, texture. 04/16/2002 • Execution result in Internet Explorer: <?xml version="1.0" ?> <!--xml document declaration --> - <SHOWS> - <PERFORMANCE> <TITLE>Fairy Princess</TITLE> <AUTHOR/> <DESCRIPTION>Scratch sound with emphasis on color, texture. </DESCRIPTION> <DATE status="canceled">04/16/2002</DATE> </PERFORMANCE> </SHOWS>

  7. XML vs. HTML in syntax • Every XML document must have one root element, i.e.,<shows>…..</shows> • Tags are case-sensitive in XML, but not in HTML • No whitespace is permitted at the beginning of a tag (i.e.,< name> is not allowed), however whitespace at the end of tag is allowed (i.e.,<name > is okay), but not a case in HTML • The tag name must start with either a letter or an underscore, but user-defined tags are not allowed in HTML • The tag names may contain any of following: letters, numerals, hyphens, periods, or underscores

  8. XML vs. HTML in Syntax(continue) • Each tag must have an end tag, the same as HTML: i.e,<date> …………….</date>, or just an empty tag as <author/>, which is incorrect in HTML • Tags must be nested i.e.,<book>…..<title> …..</book></title> is incorrect, but is okay in HTML • Attribute values must be enclosed in quotes i.e.,date status=canceled is incorrect • Comments use the same HTML syntax i.e.,<!--….comments here….-->

  9. XML Structure • Each XML file starts with an optional prolog: <?xml version=“1.0”?>, or <?xml version=“1.0” encoding=UTF-8” ?>, or <?xml version=“1.0” standalone=“yes” ?> • Each XML file must have one and only one root element • Each XML file may have DTD section (Document Type Definition) or schemas section

  10. DTD and CDATA Sections • What is DTD? - Document Type Definition describes the structural requirements of an XML document - a DTD can define the following: • The elements and attributes appeared in a file • Which elements are child elements and what number, order, and placement they must have • The default values for elements and attributes • Why DTD? - Its is used to ensure that each XML document follows a specific document model, and thus is in the exact format required for whatever processing may come its way

  11. DTD and CDATA Sections (continue) • A DTD can be saved as a separate file with .dtd file extension and be referenced by the XML file • A DTD can be completely included within the XML file • Examples of DTD file - (p. 501) – author.dtd - (downloading file: Intro to XML and XSL) – shows.dtd • DTD Generator (free download): type DTD Generator, XML in www.google.com

  12. DTD and CDATA Sections (continue) • What are CDATA sections? - Are areas in which the parser doesn’t process the XML data • Why CDATA sections? - is very useful when there is text in the XML file that needs to be passed through the parser unprocessed - to prevent the parser from reacting to offending characters in other languages

  13. DTD and CDATA Sections (continue) • An example of an element with a CDATA section: <EQUATION><![ CDATA[x > y && z <x && z > y? ] ]> </EQUATION> • General form of CDATA: <![CDATA[ your data ] ]>

  14. Concept of SAX Processing • What is SAX? - Simple API for XML in Java, now it’s called as JAXP (Java API for XML Processing) - Event-based model for accessing XML document contents • Why SAX? - Different tags as events invoke different methods by the SAX parser sequentially from start to finish - This enables us to do something as a result of the event

  15. Download and Configure SAXP pack • Download free from the following Sun’s site: http://java.sun.com/xml/index.html • The current new version is Java XML Pack - Summer 02 Update Release • After download, unzip the pack into a separate directory, i.e,SAXP • Set up the following environment parameter at DOS prompt: set SAXP_HOME=c:/SAXP/java_xml_pack-summer-02_01/jaxp-1.2_01

  16. Example of SAX Parser in Java with XML • A simple example without DTD (p. 504 –507) - steps: 1. Write a XML file (authorSimple.xml) 2. Write a Java program with SAX parser (Sax.java) 3. Compile the program as (one line command): javac –classpath .;%JAXP_HOME%\jaxp.jar; %JAXP_HOME% \crimson.jar Sax.java 4. Execute the program: java –classpath .;%JAXP_HOME%\jaxp.jar; %JAXP_HOME% \crimson.jar Sax authorSimple.xml false

  17. Example of SAX Parser in Java with XML (continue) • Execute the program with DTD: java –classpath .;%JAXP_HOME%\jaxp.jar; %JAXP_HOME% \crimson.jar Sax authorSimpleInternal.xml true • You can execute those programs without type in the long-command if you are using JDK1.4.0 or later version, i.e.: • compile: javac Sax.java false • execution: java Sax authorSimpleInternal.xml true

  18. Concept of DOM Processing • What is DOM? - Stands for Document Object Model - Is a tree structure consisting of a hierarchy of nodes stored in memory - Is used to represent the content and model of an XML file • Why DOM? - Is standard by W3C - DOM API in SAXP - Locate data in XML by access nodes of the tree - Rich interfaces and methods in DOM parser by SAXP

  19. Building a DOM Tree from a XML File • A simple example (p. 512) Dom.java - steps: 1. Write a XML file (author.xml) 2. Write a Java program with the DOM parser (Dom.java) 3. Compile the program as (one-line command): javac –classpath .;%JAXP_HOME%\jaxp.jar;%JAXP_HOME%\ crimson.jar Dom.java 4. Execute program as: java–classpath .;%JAXP_HOME%\jaxp.jar;%JAXP_HOME%\ crimson.jar Dom author.xml false

  20. Building a DOM Tree from a XML File (continue) • Example of building a DOM tree from database - (p. 515 – 517) MakeXml.java - compile: javac MakeXml.java - execute: java MakeXml - note: Make sure JDBC-ODBC is registered and the Sales table exists

  21. Concept of XSLT • What is XSLT? • Stands for eXtensible Stylesheet Language for Transformations) • XSL for formatting and XSLT for transformations • is based on XML rules • Why XSL/XSLT? • Transfer a XML document to another XML file or to HTML file • Specify the transformation as a stylesheet following XML syntax • Use templates to let processor matches against the tags in a XML file

  22. Examples of Stylesheets • Example of converting XML to HTML using stylesheet (p. 518) – authorSimple.xsl - Steps: 1. Write the .xsl file based on the .xml file (authorSimple.xml and authorSimple.xsl) 2. Write the java program to convert (XmlToHtml.java) 3. Compile as (one-line command): javac –classpath .;%JAXP_HOME%/jaxp.jar; %JAXP_HOME% /crimson.jar;%JAXP_HOME%/xalan.jar XmlToHtml.java 4. Execute as (one-line command): java –classpath .;%JAXP_HOME%/ jaxp.jar; %JAXP_HOME% /crimson.jar;%JAXP_HOME%/xalan.jar XmlToHtml authorSimple.xml authorSimple.xsl authorSimple.html

  23. Examples of Stylesheets (continue) • Another example of converting XML to HTML using stylesheet (p. 522) – author.xml, author.xsl - use XmlToHtml.java to do the conversion - steps of compilation and execution the same as last example

  24. Concept of SOAP • What is SOAP? - Stands for Simple Object Access Protocol - Is interoperability standard for Web services - Provides a simple mechanism for making remote procedure calls and document exchanges using XML • Why SOAP? - Easier to use - Distributed computing - Accessibility - XML based protocol

  25. Examples of Using SOAP Servers with Messages • Use SOAP servers and SOAP message to request information/data in XML with Java application - Xmethods site http://www.xmethods.com provides many SOAP servers and SOAP message that give us information we need to write to obtain the information/data from the SOAP server - SOAP message is an XML document that contains SOAP format we need to follow in order to send request to the server - Example of SOAP message from ITime server in Xmethods site (p. 528 Figure 13.23)

  26. Examples of Using SOAP (continue) • Example of write Java application using the SOAP message in XML (p. 529) TrySoapTime.java • Example of calling request method with arguments from the command line execution - the SOAP message from BN.com server (p. 531) Figure 13.24 - Java application using the SOAP message in XML (p. 531) GetPrice.java - to execute (online command): java GetPrice services.xmethods.net 80 /soap/servlet/ rpcrouter 0764516264

  27. SOAP API and SOAP Server Tomcat • SOAP API allows us to write clients without having to write XML request explicitly • SOAP API is free to download • SOAP server, i.e., tomcat, is also from to use • Author has re-written the section Using the SOAP API, for new section, check the site: http://www.cecs.csulb.edu/~artg/internet • Download SOAP API 2.0 soap-bin-2.0.zip from http://xml.apache.org • Download SOAP server (Tomcat 4.0) from http://jakarta.apache.org/builds/jakarta-tomcat-4.0/

  28. Configuring SOAP API and SOAP Server Tomcat • Assume the SOAP API 2.0 is installed in c:\SOAP\soap-2_2 directory, we set SOAP API home path as: set SOAP_HOME=c:\SOAP\soap-2_2 • Assume the Tomcat 4.0 is installed in c:\TOMCAT\jakarta-tomcat-4.0 directory, we set Tomcat home path as: set CATALINA_HOME=C:\TOMCAT\jakarta-tomcat-4.0

  29. Configuring SOAP API and SOAP Server Tomcat (continue) • We need to modify the classpath that Tomcat uses. In: %CATALINA_HOME%\bin\catalina.bat change the line: SET CLASSPATH=%CP% to: SET CLASSPATH=%CATALINA_HOME%\common\ lib\crimson.jar;%CP%;%SOAP_HOME%

  30. Configuring SOAP API and SOAP Server Tomcat (continue) • We need also to copy: soap.war file from: %SOAP_HOME%\webapps\ to: %CATALINA_HOME%\webapps\ so, after copy it should like this: %CATALINA_HOME%\webapps\soap.war

  31. Example of Using SOAP API with Tomcat • Example of Using SOAP API without XML - (p. 533) GetJavaPrice.java - to compile the program (one-line command): javac –classpath .;%SOAP_HOME%\lib\soap.jar GetJavaPrice.java - to execute (one-line command): java –classpath .;%SOAP_HOME%\lib\soap.jar;%CATALINA_HOME%\common\lib\crimson.jar;%CATALINA_HOME%\common\lib\mail.jar;%CATALINA_HOME%\common\lib\activation.jar GetJavaPrice 1576760235

  32. In-Class Exercises and Lab Assignment • Do TEST YOUR UNDERSTANDING 1, 3, 5, 7, 9,11, 13, and 15 • Lab Assignment (p. 536) 5, 7, and 8

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