XML and Oracle: An Overview Roger Schrag Database Specialists, Inc. www.dbspecialists.com XML and Oracle: An Overview • XML Basics • XML’s Potential • Support for XML in Oracle Products What Is XML? • A standard for representing structured data in human-readable text form • Any type of data can be represented in XML • Syntax uses open and close tags similar to HTML • Use tags common in your industry or make up your own Extensible Markup Language XML Basics • XML Documents • Document Type Definitions • Document Object Model • Simple API for XML • Transformations XML Documents An XML document is one logical unit of data marked up in XML, such as a purchase order or a stock quote. An XML datagram is a packet of data containing an XML document that is being transported between systems. An XML document is said to be well formed if it adheres to all of the syntax rules of XML. A Sample XML Document <?xml version="1.0"?> <!DOCTYPE drink-recipe SYSTEM "drink-recipe.dtd"> <drink-recipe name="Fuzzy Navel"> <ingredients> <ingredient quantity="1" unit="ounce"> Vodka </ingredient> <ingredient quantity="1" unit="ounce"> Peach schnapps </ingredient> <ingredient quantity="4" unit="ounce"> Orange juice </ingredient> </ingredients> <preparation> <step> Pour ingredients into a highball glass almost filled with ice. </step> <step> Stir. </step> </preparation> </drink-recipe> Document Type Definition (DTD) • What tags are allowed • What attributes are allowed within each tag • Which elements are required and which are optional • Which tags may be nested inside of other tags A roadmap for how to interpret a specific type of XML document: A Sample DTD <!ELEMENT drink-recipe (ingredients, preparation)> <!ATTLIST drink-recipe name CDATA #IMPLIED> <!ELEMENT ingredients (ingredient+)> <!ELEMENT ingredient (#PCDATA)> <!ATTLIST ingredient quantity CDATA #IMPLIED unit CDATA #IMPLIED> <!ELEMENT preparation (step+)> <!ELEMENT step (#PCDATA)> What Can You Do With An XML Document? Anything you can do with a plain text file: • Edit it with vi or Notepad • Move it between servers with FTP or HTTP • Store it in a VARCHAR2 or CLOB column in your Oracle database What Else Can You Do With An XML Document? • Store it in a SYS.xmltype column in your Oracle 9i database • View it with a web browser (IE 5 or Netscape 6) • View and edit it with JDeveloper • Validate it against a DTD [...]... vocabulary defines the transformation XML s Potential Why all the excitement over XML? • Strict yet extensible standards • XML + HTTP XML Standards World Wide Web Consortium recommendations set forth in 1998: • XML 1.0 specification defines XML and DTD syntax • DOM, XPath, and XSLT are covered by a separate specification Standards Both Strict and Extensible Strict: • Unambiguous and unforgiving rules... format to any other • XML allows you to decouple the data from the presentation Support for XML in Oracle Products XML Developer Kit – – – – XML Parser XSLT Processor XSQL Pages XML SQL Utility Oracle 9i SYS.xmltype Datatype Oracle Text JDeveloper PLSXML XML Developer Kit (XDK) A single Oracle module that XML- enables your Oracle database Features based on XML standards: – XML parser – DOM and SAX support... extensible standards • Oracle has shown a huge commitment to XML support in the Oracle 8i and Oracle 9i database Further Reading • “Building Oracle XML Applications” from O’Reilly by Steve Muench • Oracle 9i Application Developer's Guide – XML in the Oracle 9i server documentation set • http://technet .oracle. com/tech /xml (XML home page on Oracle Technology Network) • http://www.w3org .XML (various XML specifications... Events occur at the start and end of elements and text • Application provides custom event-handlers • Application code gets executed at specified events in document An “event-based” API XML Stylesheet Language for Transformation (XSLT) A process for transforming XML documents: • From one DTD to another • Between XML and other formats such as HTML or proprietary flat file formats An XML document using the... can insert and update XML documents as a whole, and even reference them in the WHERE clause • You cannot piece-wise update an XML document Oracle Text (interMedia) • An Oracle facility for searching text documents stored in CLOBs, BFILEs, or referenced by URLs • Adds new SQL functions CONTAINS and SCORE • Includes support for many document types, and linguistic capabilities such as stemming and fuzzy... make it easy to transport simple content, HTTP and XML together make it easy to transport data of any structure and complexity The Value of XML: The Bottom Line XML enables you to publish your complex data in the same way that HTML enables you to publish presentation content • Vendor and platform independence in the XML standard enables data transfer between disparate systems • DTDs and XSLT facilitate... parser – DOM and SAX support – XSLT processor Oracle- specific features: – XSQL pages – XML SQL utility XDK Availability and Compatibility • Installs automatically with Oracle 9i and Oracle 8i Release 3 (8.1.7) databases • Available for Oracle 8i Release 1 and 2 from the Oracle Technology Network at technet .oracle. com • Not available for Oracle7 or Oracle8 Oracle s XDK is evolving rapidly Check OTN periodically... Text indexes can be created in Oracle 9i on SYS.xmltype columns in order to index XML documents for intelligent, XML- aware searching New SQL functions such as HASPATH and INPATH become available JDeveloper Oracle s interactive application development environment XML- aware capabilities: XML document editing and syntax checking •XSLT manipulation •XSQL page development and viewing PLSXML A simple PL/SQL... Based on XML Standards XML Parser, DOM, SAX, XSLT Processor • Multitude of Java classes • PL/SQL packages such as xmlparser and xmldom These are really PL/SQL wrappers encapsulating Java code • Command line utilities such as oraxml and oraxsl These are really shell script wrappers encapsulating Java code XSQL Pages (Java XDK only) A facility for quickly publishing data in XML • Prepare an XML document... query as an XML document • Download PLSXML from technet .oracle. com (search for “PLSXML”) • A very simplistic script that demonstrates converting table data to XML documents, but probably has little value beyond a demonstration • Oracle s one XML offering for Oracle7 and Oracle8 users Wrapping Up • XML is a platform independent, vendor independent method for transporting structured data • XML is defined . XML and Oracle: An Overview Roger Schrag Database Specialists, Inc. www.dbspecialists.com XML and Oracle: An Overview • XML Basics • XML s Potential • Support for XML in Oracle Products . document An API for scanning XML documents An “event-based” API XML Stylesheet Language for Transformation (XSLT) A process for transforming XML documents: • From one DTD to another • Between XML and. formats An XML document using the XSLT vocabulary defines the transformation. XML s Potential Why all the excitement over XML? • Strict yet extensible standards • XML + HTTP XML Standards • XML