174 DBMS_XMLPARSER

Using DBMS_XMLPARSER, you can access the contents and structure of XML documents. XML describes a class of data XML document objects. It partially describes the behavior of computer programs which process them. By construction, XML documents are conforming SGML documents.

XML documents are made up of storage units called entities, which contain either parsed or unparsed data. Parsed data is made up of characters, some of which form character data, and some of which form markup. Markup encodes a description of the document's storage layout and logical structure. XML provides a mechanism to impose constraints on the storage layout and logical structure.

A software module called an XML processor is used to read XML documents and provide access to their content and structure. It is assumed that an XML processor is doing its work on behalf of another module, called the application. This PL/SQL implementation of the XML processor (or parser) follows the W3C XML specification REC-xml-19980210 and includes the required behavior of an XML processor in terms of how it must read XML data and the information it must provide to the application.

The default behavior for this PL/SQL XML parser is to build a parse tree that can be accessed by DOM APIs, validate it if a DTD is found (otherwise, it is non-validating), and record errors if an error log is specified. If parsing fails, an application error is raised.

This chapter contains the following topics:

Using DBMS_XMLPARSER
Summary of DBMS_XMLPARSER Subprograms

Using DBMS_XMLPARSER

Security Model

Security Model

Owned by XDB, the DBMS_XDB_XMLPARSER package must be created by SYS or XDB. The EXECUTE privilege is granted to PUBLIC. Subprograms in this package are executed using the privileges of the current user.

Summary of DBMS_XMLPARSER Subprograms

Table 174-1 DBMS_XMLPARSER Package Subprograms

Method	Description
FREEPARSER	Frees a parser object.
GETDOCTYPE	Gets parsed DTD.
GETDOCUMENT	Gets DOM document.
GETRELEASEVERSION	Returns the release version of Oracle XML Parser for PL/SQL.
GETVALIDATIONMODE	Returns validation mode.
NEWPARSER	Returns a new parser instance
PARSE	Parses XML stored in the given url/file.
PARSEBUFFER	Parses XML stored in the given buffer
PARSECLOB	Parses XML stored in the given clob
PARSEDTD	Parses DTD stored in the given url/file
PARSEDTDBUFFER	Parses DTD stored in the given buffer
PARSEDTDCLOB	Parses DTD stored in the given clob
SETBASEDIR	Sets base directory used to resolve relative URLs.
SETDOCTYPE	Sets DTD.
SETERRORLOG	Sets errors to be sent to the specified file
SETPRESERVEWHITESPACE	Sets white space preserve mode
SETVALIDATIONMODE	Sets validation mode.
SHOWWARNINGS	Turns warnings on or off.

FREEPARSER

Frees a parser object.

Syntax

PROCEDURE freeParser(
    p Parser);

Parameter	IN / OUT	Description
`p`	`(IN)`	Parser instance.

GETDOCTYPE

Returns the parsed DTD; this function must be called only after a DTD is parsed.

Syntax

FUNCTION getDoctype(
p Parser)
RETURN DOMDocumentType;

Parameter	IN / OUT	Description
`p`	`(IN)`	Parser instance.

GETDOCUMENT

Returns the document node of a DOM tree document built by the parser; this function must be called only after a document is parsed.

Syntax

FUNCTION GETDOCUMENT(
p Parser)
RETURN DOMDocument;

Parameter	IN / OUT	Description
`p`	`(IN)`	Parser instance.

GETRELEASEVERSION

Returns the release version of the Oracle XML parser for PL/SQL.

Syntax

FUNCTION getReleaseVersion
RETURN VARCHAR2;

GETVALIDATIONMODE

Retrieves validation mode; TRUE for validating, FALSE otherwise.

Syntax

FUNCTION GETVALIDATIONMODE(
p Parser)
RETURN BOOLEAN;

Parameter	IN / OUT	Description
`p`	`(IN)`	Parser instance.

NEWPARSER

Returns a new parser instance. This function must be called before the default behavior of Parser can be changed and if other parse methods need to be used.

Syntax

FUNCTION newParser 
RETURN Parser;

PARSE

Parses XML stored in the given URL or file. An application error is raised if parsing fails. There are several versions of this method.

Syntax Description

Syntax	Description
`FUNCTION parse(` `url VARCHAR2)` `RETURN DOMDocument;`	Returns the built DOM Document. This is meant to be used when the default parser behavior is acceptable and just a url/file needs to be parsed.
`PROCEDURE parse(` `p Parser,` `url VARCHAR2);`	Any changes to the default parser behavior should be effected before calling this procedure.

FUNCTION parse(

url VARCHAR2)

RETURN DOMDocument;

Returns the built DOM Document. This is meant to be used when the default parser behavior is acceptable and just a url/file needs to be parsed.

PROCEDURE parse(

p Parser,

url VARCHAR2);

Any changes to the default parser behavior should be effected before calling this procedure.

Parameter	IN / OUT	Description
`url`	`(IN)`	Complete path of the url/file to be parsed.
`p`	`(IN)`	Parser instance.

PARSEBUFFER

Parses XML stored in the given buffer. Any changes to the default parser behavior should be effected before calling this procedure. An application error is raised if parsing fails.

Syntax

PROCEDURE PARSEBUFFER(
p   Parser,
doc VARCHAR2);

Parameter	IN / OUT	Description
`p`	`(IN)`	Parser instance.
`doc`	`(IN)`	XML document buffer to parse.

PARSECLOB

Parses XML stored in the given clob. Any changes to the default parser behavior should be effected before calling this procedure. An application error is raised if parsing fails.

Syntax

PROCEDURE PARSECLOB(
p   Parser,
doc CLOB);

Parameter	IN / OUT	Description
`p`	`(IN)`	Parser instance.
`doc`	`(IN)`	XML document buffer to parse.

PARSEDTD

Parses the DTD stored in the given URL or file. Any changes to the default parser behavior should be effected before calling this procedure. An application error is raised if parsing fails.

Syntax

PROCEDURE PARSEDTD(
p     Parser,
url   VARCHAR2,
root  VARCHAR2);

Parameter	IN / OUT	Description
`p`	`(IN)`	Parser instance.
`url`	`(IN)`	Complete path of the URL or file to be parsed.
`root`	`(IN)`	Name of the root element.

PARSEDTDBUFFER

Parses the DTD stored in the given buffer. Any changes to the default parser behavior should be effected before calling this procedure. An application error is raised if parsing fails.

Syntax

PROCEDURE PARSEDTDBUFFER(
p    Parser,
dtd  VARCHAR2,
root VARCHAR2);

Parameter	IN / OUT	Description
`p`	`(IN)`	Parser instance.
`dtd`	`(IN)`	DTD buffer to parse.
`root`	`(IN)`	Name of the root element.

PARSEDTDCLOB

Parses the DTD stored in the given clob. Any changes to the default parser behavior should be effected before calling this procedure. An application error is raised if parsing fails.

Syntax

PROCEDURE PARSEDTDCLOB(
p    Parser,
dtd  CLOB,
root VARCHAR2);

Parameter	IN / OUT	Description
`p`	`(IN)`	Parser instance.
`dtd`	`(IN)`	DTD Clob to parse.
`root`	`(IN)`	Name of the root element.

SETBASEDIR

Sets base directory used to resolve relative URLs. An application error is raised if parsing fails.

Syntax

PROCEDURE setBaseDir(
p   Parser,
dir VARCHAR2);

Parameter	IN / OUT	Description
`p`	`(IN)`	Parser instance.
`dir`	(IN)	Directory used as a base directory.

SETDOCTYPE

Sets a DTD to be used by the parser for validation. This call should be made before the document is parsed.

Syntax

PROCEDURE setDoctype(
p   Parser,
dtd DOMDocumentType);

Parameter	IN / OUT	Description
`p`	`(IN)`	Parser instance.
`dtd`	`(IN)`	DTD to set.

SETERRORLOG

Sets errors to be sent to the specified file.

Syntax

PROCEDURE setErrorLog(
p        Parser,
fileName VARCHAR2);

Parameter	IN / OUT	Description
`p`	`(IN)`	Parser instance.
`fileName`	`(IN)`	Complete path of the file to use as the error log.

SETPRESERVEWHITESPACE

Sets whitespace preserving mode.

Syntax

PROCEDURE setPreserveWhitespace(
p   Parser,
yes BOOLEAN);

Parameter	IN / OUT	Description
`p`	`(IN)`	Parser instance.
`yes`	`(IN)`	Mode to set: `TRUE` - preserve, `FALSE` - don't preserve.

SETVALIDATIONMODE

Sets validation mode.

Syntax

PROCEDURE setValidationMode(
p   Parser,
yes BOOLEAN);

Parameter	IN / OUT	Description
`p`	`(IN)`	Parser instance.
`yes`	`(IN)`	Mode to set: `TRUE` - validate, `FALSE` - don't validate.

SHOWWARNINGS

Turns warnings on or off.

Syntax

PROCEDURE showWarnings(
p   Parser,
yes BOOLEAN);

Parameter	IN / OUT	Description
`p`	`(IN)`	Parser instance.
`yes`	`(IN)`	Mode to set: `TRUE` - show warnings, `FALSE` - don't show warnings.