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IA307 - Data Exchange with XML

IA307 - Data Exchange with XML. Christophe Coenraets Manager, Technical Evangelists Internet Applications Division ccoenrae@sybase.com. Topics. Drawbacks of HTML What is XML? Document Type Declaration (DTD) Extensible Style Language (XSL) XML and Java Simple API for XML (SAX)

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IA307 - Data Exchange with XML

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  1. IA307 - Data Exchange with XML Christophe Coenraets Manager, Technical Evangelists Internet Applications Division ccoenrae@sybase.com

  2. Topics • Drawbacks of HTML • What is XML? • Document Type Declaration (DTD) • Extensible Style Language (XSL) • XML and Java • Simple API for XML (SAX) • Document Object Model (DOM)

  3. TripFinder.htm Page <center><h1>Trip Finder</h1> <form action="TripFinder.jsp"> <table border=0> <tr><td>Origin:</td><td><input name="origin" value="bos"></td></tr> <tr><td>Destination:</td><td><input name="destination" value="ARU"></td></tr> <tr><td>Date:</td><td><input name="date" value="01/01/1900"></td></tr> </table><br><input type="submit" value="Search"></form> <p><table border=1 cellpadding=4> <tr><td><a href=Payment.jsp?trip=2&amount=2200>Book it</a></td> <td>TNT</td><td>Grand Hyatt Aruba</td><td>2000-05-01</td><td>7</td><td>2200</td></tr> <tr><td><a href=Payment.jsp?trip=8&amount=1900>Book it</a></td> <td>TNT</td><td>Plaza Hotel</td><td>2000-06-01</td><td>7</td><td>1900</td></tr> <tr><td><a href=Payment.jsp?trip=9&amount=2100>Book it</a></td> <td>GWV</td><td>Marriott Aruba</td><td>2000-06-01</td><td>7</td><td>2100</td></tr> </table></center>

  4. Drawbacks of HTML • HTML document contains both data and formatting • HTML tags • Describe how page elements should look • Don't contain any information about what the data is • Issues • Difficult to identify and extract data from the document • Difficult to change the presentation style

  5. What is XML? • Extensible Markup Language • World Wide Web Consortium standard that lets you create your own tags • Universal data description mechanism • XML separates the data and presentation • Makes documents suitable for data interchange • Allows alternative presentation styles • Simplifies business-to-business transactions on the web

  6. XML DocumentTrip.xml <?xml version="1.0" ?> <trip> <trip_id>2</trip_id> <origin>BOS</origin> <destination>ARU</destination> <hotel>Grand Hyatt Aruba</hotel> <arrival_date>2000-05-01</arrival_date> <days>7</days> <price>2200</price> </trip>

  7. XML Document Characteristics • No presentation information • No specification of type style or color • No specification of format: table, list, bold, etc • Tags are application-oriented • <destination>, <hotel>, etc, instead of just <p> • Easy to distinguish “123” as TripId vs Price

  8. Enabling Business-to-Business (B2B) <TripRequest> </TripRequest> Tour Operator <TripList></TripList> Travel Agent TripList.xmlTripList.xsl <TripList></TripList> Tour Operator <TripRequest> </TripRequest>

  9. Well Formed XML documents • An XML document is well-formed if it is syntactically correct • Document starts with <?xml…> • Tags are strictly nested • Each open <tag> has a corresponding close </tag>

  10. Valid XML documents • An XML document is valid if it specifies and conforms to the document rules defined in a DTD • Valid XML documents are well-formed • Well-formed XML documents may be valid

  11. Document Type Declaration (DTD) • Specifies a Document Type • Defines set of rules, grammar document must comply to • Allows for predictable data

  12. Vacation DTDExample <!ELEMENT trip (origin, destination, hotel, arrival, nights, price)> <!ELEMENT origin (#PCDATA)> <!ELEMENT destination (#PCDATA)> <!ELEMENT hotel (#PCDATA)> <!ELEMENT arrival (#PCDATA)> <!ELEMENT nights (#PCDATA)> <!ELEMENT price (single, double)> <!ELEMENT single (#PCDATA)> <!ELEMENT double (#PCDATA)> <!ATTLIST hotel rating (na|1|2|3|4) "na">

  13. XML DocumentTrips.xml <?xml version="1.0" ?> <!DOCTYPE vacation SYSTEM "vacation.dtd"> <trips> <trip> <trip_id>2</trip_id> <origin>BOS</origin> <destination>ARU</destination> <hotel>Grand Hyatt Aruba</hotel> <arrival_date>2000-05-01</arrival_date> <days>7</days> <price>2200</price> </trip> </trips>

  14. Presentation Using XSL • XML documents omit all formatting • Formatting is supplied by XSL • XSL: “Extensible Style Language” • Specified separate from the XML document • Allows multiple XSL specs for one XML document • An XSL spec maps • An XML document type to HTML, or • One XML document type to another

  15. XML and Java • Java and XML are complementary Technologies • Java = Code Portability • XML = Data Portability • Java Parsers facilitate XML document manipulation • Validate an XML document • Handle character set issues, etc • Return a Java object (a tree) for the document • Also used to build such a tree and generate a document

  16. XML Parsers • Many XML parsers are available • Often with free license or public domain • XML parsers use two standard interfaces • SAX and DOM • Applications using SAX & DOM • Can be portable across XML parsers

  17. Simple API for XML (SAX) • Event-driven interface to XML parsers • org. xml. sax.* package Event <?xml version="1.0" ?> <trip> … </trip> Event SAX Event

  18. Document Object Model (DOM) • Tree data structure interface to XML parser • Models document structure as objects • Defines a Java programming language binding: • org. w3c. dom.* package • DOM is also used to build XML documents <?xml version="1.0" ?> <trip> … </trip> DOM

  19. Creating TripListXML.jspDemo Tour Operator <TripList></TripList> Travel Agent TripList.xmlTripList.xsl <TripList></TripList> Tour Operator

  20. Summary

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