Using XML Parser for PL/SQL (DOM Interface)

The XML Parser for PL/SQL makes developing XML applications with Oracle8i a simplified and standardized process. With the PL/SQL interface, Oracle shops familiar with PL/SQL can extend existing applications to take advantage of XML as needed.

Since the XML Parser for PL/SQL is implemented in PL/SQL and Java, it can run "out of the box" on the Oracle8i Java Virtual Machine.

XML Parser for PL/SQL supports the W3C XML 1.0 specification. The goal is to be 100% conformant.. It can be used both as a validating or non-validating parser.

In addition, XML Parser for PL/SQL provides the two most common API's developers need for processing XML documents:

• W3C-recommended Document Object Model (DOM)

• XSL-T and XPath recommendations

This makes writing custom applications that process XML documents straightforward in the Oracle8i environment, and means that a standards-compliant XML parser is part of the Oracle8i platform on every operating system where Oracle8i is ported.

Figure 24-1 shows the XML Parser for PL/SQL usage and parsing process diagram.

1. Make a newParser declaration to begin the parsing process for the XML document and DTD, if applicable.

   Table 24-1 lists available properties for the newParser procedure:

   Table 24-1 XML Parser for PL/SQL: newParser() Properties

   Property	Description
   setValidationMode	Default = Not
   setPreserveWhiteSpace	Default = Not
   setDocType	Use if input type is a DTD
   setBaseURL	Refers to other locations to the base locations, if reading from an outside source
   showWarnings	Turns warnings on or off.

2. The XML and DTD can be input as a file, varchar buffer, or CLOB. The XML input is called by the following procedures:
   • parse() if the XML input is a file

   • parseBuffer() if the XML input is an varchar buffer

   • parserClob() if the XML input is a CLOB

   If a DTD is also input, it is called by the following procedures:

   • parseDTD() if the input is an DTD file

   • parseDTDBuffer() if the DTD input is an varchar buffer

   • parserDTDClob() if the DTD input is a CLOB

For the XML Input: For an XML input, the parsed result from Parse(), ParserBuffer(), or ParserClob() procedures is sent to GetDocument().

3. getDocument() procedure performs the following:
   • Outputs the parsed XML document as a DOM document typically to be used in a PL/SQL application, or

   • Applies other DOM functions, if applicable. See Oracle8i XML Reference for a list of available optional DOM functions.

4. Use freeDocument() function to free up the parser and parse the next XML input

5. Use freeParser() to free up any temporary document structures created during the parsing process

For the DTD input: The parsed result from parseDTD(), parseDTDBuffer(), or parseDTDClob() is used by getDocType() function.

6. getDocType() then uses setDocType() to generate a DTD object.

7. The DTD object can be fed into the parser using setDocType() to override the associated DTD.

Figure 24-1 XML Parser for PL/SQL Functionality (DOM Interface)

XML Parser for PL/SQL: Default Behavior

The following is the default behavior for XML Parser for PLSQL XML:

• A parse tree which can be accessed by DOM APIs is built

• The parser is validating if a DTD is found, otherwise it is non-validating

• Errors are not recorded unless an error log is specified; however, an application error will be raised if parsing fails

The types and methods described in this manual are supplied with the PLSQL package xmlparser().