Using XML in Database Applications

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Using XML in Database Applications
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• Overview
• Oracle Solutions to Database Applications

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Overview

• XML stands for eXensible Markup Language.
• HTML vs. XML
• HTML tags elements in web pages for presentation
  by a browser, while XML tags elements as content
  or data.

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Example

• HTML Example
• lttablegt
• lttrgt
• lttdgtEMPNOlt/tdgtlttdgtENAMElt/tdgtlttdgtJOBlt/tdgtlttdgtSALlt/t
  dgt
• lt/trgt
• lttrgt
• lttdgt7654lt/tdgtlttdgtMARTINlt/tdgtlttdgtSALESMANlt/tdgtlttdgt1
  250lt/tdgt
• lt/trgt
• lttrgt
• lttdgt7788lt/tdgtlttdgtSCOTTlt/tdgtlttdgtANALYSTlt/tdgtlttdgt300
  0lt/tdgt
• lt/trgt
• lt/tablegt

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Example Cont

• lt?xml version"1.0"?gt
• ltEMPLISTgt
• ltEMPgt
• ltEMPNOgt7654lt/EMPNOgt
• ltENAMEgtMARTINlt/ENAMEgt
• ltJOBgtSALESMANlt/JOBgt
• ltSALgt1250lt/SALgt
• lt/EMPgt
• ltEMPgt
• ltEMPNOgt7788lt/EMPNOgt
• ltENAMEgtSCOTTlt/ENAMEgt
• ltJOBgtANALYSTlt/JOBgt
• ltSALgt3000lt/SALgt
• lt/EMPgt
• lt/EMPLISTgt

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Benefit

• Presentation is separate from its structure and
  content. The XML data defines the structure and
  content, and then a stylesheet is applied to it
  to define the presentation.
• XML leaves the specification of tags and how they
  can be used by users. Tags may be defined by
  using them in an XML document or formally defined
  in a Document Type Definition (DTD).

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XSL

• The eXtensible Stylesheet Language, XSL, provides
  for stylesheets that allow you to transform XML
  into HTML or other text-based formats, rearrange
  or filter data, or convert it to XML that
  conforms to another DTD-an important capability
  for allowing different applications to share
  data.

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Well-Formed and Valid XML Document

• Well-formed XML allows you to invent your own
  tags.
• Valid XML involves a DTD (Document
• Type Definition) that tells the labels and
• gives a grammar for how they may be
• nested.

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Well-Formed XML Document Rules

• The document must start with the XML declaration
  lt?xml version"1.0"gt
• All elements must be contained within one root
  element
• Elements must be nested in a tree structure
  without overlapping
• All non-empty elements must have start and end
  tags

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Example DTD

• lt!DOCTYPE EMPLISTgt
• lt!ELEMENT EMPLIST (EMP)gt
• lt!ELEMENT EMP (EMPNO, ENAME, JOB, SAL)gt
• lt!ELEMENT EMPNO (PCDATA)gt
• lt!ELEMENT ENAME (PCDATA)gt
• lt!ELEMENT JOB (PCDATA)gt
• lt!ELEMENT SAL (PCDATA)gt
• gt

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Oracle Solutions to Database Applications

• Key Oracle products that support XML in database
  applications include
• Oracle8i and interMedia
• XML Parsers and XSL Processors (Java, C, C, and
  PL/SQL)
• XML Class Generators (Java and C)
• XML SQL Utility for Java

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Oracle Solutions Cont.

• XSQL Servlet
• XML Transviewer Beans
• The XML Parsers, XSL Processors, XML Class
  Generator, and XML Transviewer Beans are packaged
  together in the Oracle XML Developer's Kit (XDK).
  You can run the these components in the Oracle8i
  server, on a middle tier such as Oracle
  Application Server, or on the client.

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DOM and SAX

• DOM
• Document Object Model is tree-based API, which
  needs to build in-memory tree representation of
  XML document.
• SAX
• Simple API for XML is event-based and event
  handlers are used to deal with event like start
  and end of elements and characters.

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XML SQL Utility for Java
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Cont.
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XSQL Sevlet