XML Parser for PL/SQL Example: PL/SQL — xslsample.sql

Using XML Parser for PL/SQL Examples in the Sample Directory



-- new parser

p := xmlparser.newParser;

-- set some characteristics

xmlparser.setValidationMode(p, FALSE);

xmlparser.setErrorLog(p, dir || '/' || errfile);

xmlparser.setPreserveWhiteSpace(p, TRUE);

xmlparser.setBaseDir(p, dir);

-- parse xml file

dbms_output.put_line('Parsing XML document ' || dir || '/' || xmlfile);

xmlparser.parse(p, dir || '/' || xmlfile);

-- get document

xmldoc := xmlparser.getDocument(p);

-- parse xsl file

dbms_output.put_line('Parsing XSL document ' || dir || '/' || xslfile);

xmlparser.parse(p, dir || '/' || xslfile);

-- get document

xsldoc := xmlparser.getDocument(p);

xslelem := xmldom.getDocumentElement(xsldoc);

nspace := xmldom.getNamespace(xslelem);

-- print out some information about the stylesheet

dbms_output.put_line('XSL Root element information');

dbms_output.put_line('Qualified Name: ' ||

xmldom.getQualifiedName(xslelem));

dbms_output.put_line('Local Name: ' ||

xmldom.getLocalName(xslelem));

dbms_output.put_line('Namespace: ' || nspace);

dbms_output.put_line('Expanded Name: ' ||

xmldom.getExpandedName(xslelem));

xslcmds := xmldom.getChildrenByTagName(xslelem, '*', nspace);

dbms_output.put_line('A total of ' || xmldom.getLength(xslcmds) ||

' XSL instructions were found in the stylesheet');

-- make stylesheet

ss := xslprocessor.newStylesheet(xsldoc, dir || '/' || xslfile);

-- process xsl

proc := xslprocessor.newProcessor;

xslprocessor.showWarnings(proc, true);



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xslprocessor.setErrorLog(proc, dir || '/' || errfile);

dbms_output.put_line('Processing XSL stylesheet');

docfrag := xslprocessor.processXSL(proc, ss, xmldoc);

docfragnode := xmldom.makeNode(docfrag);

dbms_output.put_line('Writing transformed document');

xmldom.writeToFile(docfragnode, dir || '/' || resfile);

-- deal with exceptions

exception

when xmldom.INDEX_SIZE_ERR then

raise_application_error(-20120, 'Index Size error');

when xmldom.DOMSTRING_SIZE_ERR then

raise_application_error(-20120, 'String Size error');

when xmldom.HIERARCHY_REQUEST_ERR then

raise_application_error(-20120, 'Hierarchy request error');

when xmldom.WRONG_DOCUMENT_ERR then

raise_application_error(-20120, 'Wrong doc error');

when xmldom.INVALID_CHARACTER_ERR then

raise_application_error(-20120, 'Invalid Char error');

when xmldom.NO_DATA_ALLOWED_ERR then

raise_application_error(-20120, 'Nod data allowed error');

when xmldom.NO_MODIFICATION_ALLOWED_ERR then

raise_application_error(-20120, 'No mod allowed error');

when xmldom.NOT_FOUND_ERR then

raise_application_error(-20120, 'Not found error');

when xmldom.NOT_SUPPORTED_ERR then

raise_application_error(-20120, 'Not supported error');

when xmldom.INUSE_ATTRIBUTE_ERR then

raise_application_error(-20120, 'In use attr error');

end xslsample;

/

show errors;



XML Parser for PL/SQL 20-15



Frequently Asked Questions About the XML Parser for PL/SQL



Frequently Asked Questions About the XML Parser for PL/SQL

Why Do I Get an "Exception in Thread" Parser Error?

When I try to use the oraxsl I get the following: Exception in thread main:

java.lang.NoClassDefFoundError" oracle/xml/parser/v2/oraxsl.



How do I fix this?

Answer: If you are running outside the database you need to make sure the

xmlparserv2.jar is explicitly in your CLASS_PATH, not simply its directory. If

from the database you need to make sure it has been properly loaded and that

JServer initialized.



How Do I Use the xmldom.GetNodeValue in PL/SQL?

I cannot get the element value using the PL/SQL XMLDOM. Here is the code

fragment:

...nl := xmldom.getElementsByTagName(doc, '*');

len := xmldom.getLength(nl)

;-- loop through elements

for i in 0..len-1 loop

n := xmldom.item(nl, i);

elename := xmldom.getNodeName(n);

eleval := xmldom.getNodeValue(n);

...elename is Ok, but eleval is NULL.



Associating with a text node does not seem to work, or I am not doing it correctly? I

receive a compile error, as in this example:

...t xmldom.DOMText;

...t := xmldom.makeText(n);

eleval := xmldom.getNodeValue(t);



What am I doing wrong?

Answer: To get the text node value associated with the element node, you must

perform additional node navigation through xmldom.getFirstChild(n).

To illustrate, change printElements() in DOMSample.sql as follows:

begin

-- get all elements

nl := xmldom.getElementsByTagName(doc, '*');

len := xmldom.getLength(nl);



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-- loop through elements

for i in 0..len-1 loop

n := xmldom.item(nl, i);

dbms_output.put(xmldom.getNodeName(n));

-- get the text node associated with the element node

n := xmldom.getFirstChild(n);

if xmldom.getNodeType(n) = xmldom.TEXT_NODE then

dbms_output.put('=' | | xmldom.getNodeValue(n));

end if;

dbms_output.put(' ');

end loop;

dbms_output.put_line('');

end printElements;



This produces the following output, listing the elements:

family member=Sarah member=Bob member=Joanne member=Jim



The attributes of each element are:

family:familylastname val=Smithmember:membermemberid val=m1member:membermemberid

val=m2member:membermemberid val=m3 mom val=m1 dad val=m2member:membermemberid

val=m4 mom val=m1 dad val=m2



Can I Run the XDK for PL/SQL in an IIS Environment?

I downloaded XDK for PL/SQL but it requires OAS. Do you have any idea how to

run this in an IIS environment?

Answer: If you're going to use IIS, it would be better to use the XML Parser for Java

version 2. You'll also need Oracle9i.



How Do I Parse a DTD Contained in a CLOB with the XML Parser for PL/SQL?

I am having problems parsing a DTD file contained in a CLOB. I used the

xmlparser.parseDTDClob API, provided by the XML Parser for PL/SQL.

I received the following error:

"ORA-29531: no method parseDTD in class oracle/xml/parser/plsql/XMLParserCover".



The procedure xmlparser.parseDTDClob calls a Java Stored Procedure

xmlparsercover.parseDTDClob, which in turn calls another Java Stored

Procedure xmlparsercover.parseDTD.

I have confirmed that the class file,

oracle.xml.parser.plsql.XMLParserCover, has been loaded into the



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Frequently Asked Questions About the XML Parser for PL/SQL



database, and that it has been published. So the error message does not make sense.

The procedure used to call xmlparser.parseDTDClob is:

create or replace procedure parse_my_dtd as p xmlparser.parser; l_clob clob;

begin p := xmlparser.newParser; select content into l_clob from

dca_documents where doc_id = 1;

xmlparser.parseDTDClob(p,l_clob,'site_template'); end; API Documentation for

xmlparser.parseDTDClob:

parseDTDClob PURPOSE Parses the DTD stored in the given clob SYNTAX

PROCEDURE parseDTDClob(p Parser, dtd CLOB, root VARCHAR2); PARAMETERS p

(IN)- parser instance dtd

(IN)- dtd clob to parse root

(IN)- name

of the root element RETURNS Nothing COMMENTS



Any changes to the default parser behavior should be made before calling this

procedure. An application error is raised if parsing failed, for some reason.

Description of the table dca_documents:

DOC_ID

NOT NULL NUMBER DOC_NAME

NOT NULL

DOC_TYPE

VARCHAR2(30)

DESCRIPTION

VARCHAR2(4000) MIME_TYPE

VARCHAR2(48) CONTENT

NOT NULL CLOB CREATED_BY

VARCHAR2(30) CREATED_ON

NOT NULL DATE UPDATED_BY

VARCHAR2(30) UPDATED_ON

NOT NULL DATE



VARCHAR2(350)



NOT NULL

NOT NULL



The contents of the DTD:


#REQUIRED>
component (#PCDATA)>
component parent_id ID #REQUIRED>
#REQUIRED>



Answer: This is a known issue in release 1.0.1 of the XML Parser for PL/SQL. Here

is the workaround.

First, make a backup of

./plsqlxmlparser_1.0.1/lib/sql/xmlparsercover.sql

Then, in line 18 of xmlparsercover.sql, change the string

oracle.xml.parser.plsql.XMLParserCover.parseDTD to

oracle.xml.parser.plsql.XMLParserCover.parseDTDClob

Verify that Line 18 now reads:

procedure parseDTDClob(id varchar2, DTD CLOB, root varchar2, err in out



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Frequently Asked Questions About the XML Parser for PL/SQL



varchar2)

is language java name

'oracle.xml.parser.plsql.XMLParserCover.parseDTDClob(java.lang.String,

oracle.sql.CLOB, java.lang.String, java.lang.String[])';



Save the file, then rerun xmlparsercover.sql in SQL*Plus. Assuming you've

loaded XMLParser version 2 release 2.0.2.6 into the database, this should solve your

problem.



How Do I Use Local Variables with the XML Parser for PL/SQL?

I have just started using XML Parser for PL/SQL. I am have trouble getting the text

between the begin tag and the end tag into a local variable. Do you have examples?

Answer: You just have to use the following:

selectSingleNode("pattern");

getNodeValue()



Remember, if you are trying to get value from a Element node, you have to move

down to the #text child node, for example, getFirstChild.getNodeValue()

Suppose you need to get the text contained between the starting and ending tags of

a xmldom.DOMNode n. The following two lines will suffice.

n_child:=xmldom.getFirstChild(n);

text_value:=xmldom.getNodeValue(n_child));



n_child is of type xmldom.DOMNode.

text_value is of type varchar2.



Why Do I Get a Security Error When I Grant JavaSysPriv to a User?

We are using the XML Parser for PLSQL and are trying to parse an XML document.

We are getting a Java security error:

ORA-29532: Java call terminated by uncaught Java exception:

java.lang.SecurityException ORA-06512: at "NSEC.XMLPARSERCOVER", line 0

ORA-06512: at "NSEC.XMLPARSER", line 79 ORA-06512: at "NSEC.TEST1_XML line 36

ORA-06512: at line 5



Do we need to grant to user? The syntax appears correct. We also get the error when

we run the demo.



XML Parser for PL/SQL 20-19



Frequently Asked Questions About the XML Parser for PL/SQL



Answer: If the document you are parsing contains a doctype which has a System

URI with a protocol like file:/// or http:/// then you need to grant an

appropriate privilege to your current database user to be able to "reach out of the

database", so to speak, and open a stream on the file or URL.CONNECT

SYSTEM/MANAGER. The following code should do it:

GRANT JAVAUSERPRIV, JAVASYSPRIV TO youruser;



How Do I Install the XML Parser for PL/SQL with the JServer (JVM) Option?

I have downloaded and installed the plxmlparser_V1_0_1.tar.gz. The

readme said to use loadjava to upload xmlparserv2.jar and plsql.jar in

order. I tried to load xmlparserv2.jar using the following command:

loadjava -user test/test -r -v xmlparserv2.jar



to upload the jar file into Oracle8i. After much of the uploading, I got the following

error messages:

identical: oracle/xml/parser/v2/XMLConstants is unchanged from previously loaded

fileidentical: org/xml/sax/Locator is unchanged from previously loaded

fileloading : META-INF/MANIFEST.MFcreating : META-INF/MANIFEST.MFError while

creating resource META-INF/MANIFEST.MF

ORA-29547: Java system class not

available: oracle/aurora/rdbms/Compilerloading :

oracle/xml/parser/v2/mesg/XMLErrorMesg_en_US.propertiescreating :

oracle/xml/parser/v2/mesg/XMLErrorMesg_en_US.propertiesError while creating

...



Then I removed -r from the previous command:

loadjava -user test/test -v xmlparserv2.jar



I still got errors but it's down to four:

.identical: org/xml/sax/Locator is unchanged from previously loaded fileloading

: META-INF/MANIFEST.MFcreating : META-INF/MANIFEST.MFError while creating

...



I think I have installed the JServer on the database correctly.

Answer: The JServer option is not properly installed if you're getting errors like this

during loadjava. You need to run INITJVM.SQL and INITDBJ.SQL to get the

JavaVM properly installed. Usually these are in the ./javavm subdirectory of your

Oracle Home.



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Frequently Asked Questions About the XML Parser for PL/SQL



How Do I Use the domsample Included with XML Parser for PL/SQL?

I am trying to execute domsample on dom1151. This is an example that is provided

with the XML Parser for PL/SQL. The XML file family.xml is present in the

directory /hrwork/log/pqpd115CM/out.

I am getting the following error:

Usage of domsample is domsample(dir, inpfile, errfile)

SQL>

begin

domsample('/hrwork/log/pqpd115CM/out','family.xml','errors.txt');

end;

/

Error generated :

begin

*

ERROR at line 1:

ORA-20100: Error occurred while parsing: No such file or directory

ORA-06512: at "APPS.XMLPARSER", line 22

ORA-06512: at "APPS.XMLPARSER", line 69

ORA-06512: at "APPS.DOMSAMPLE", line 80

ORA-06512: at line 2



Answer: From your description it sounds like you have not completed all of the

steps in the sample and Readme without errors. After confirming that the

xmlparserv2.jar is loaded, carefully complete the steps again.



How Do I Extract Part of a CLOB?

In an Oracle8i database, we have CLOBs which contain well-formed XML

documents up to 1 MB in size.

We want the ability to extract only part of the CLOB (XML document), modify it,

and replace it back in the database rather than processing the entire document.

Second, we want this process to run entirely on the database tier.

Which products or tools are needed for this? This may be possible with the JVM

which comes with Oracle9i. There also may be some PL/SQL tools available to

achieve this by means of stored procedures.

Answer: You can do this by using either of the following:

s



Oracle XML Parser for PLSQL



XML Parser for PL/SQL 20-21



Frequently Asked Questions About the XML Parser for PL/SQL



s



Create your own custom Java stored procedure wrappers over some code you

write yourselves with the Oracle XML Parser for Java.



XML Parser for PLSQL has methods such as the following:

s



s



xmlparser.parseCLOB()

xslProcessor.selectNodes(), to find what part of the doc you are looking

for



s



xmldom.* methods to manipulate the content of the XML document



s



xmldom.writeToCLOB() to write it back



If you wanted to do fine-detail updates on the text of the CLOB, you would have to

use DBMS_LOB.* routines, but this would be tricky unless the changes being made

to the content don't involve any increase or decrease in the number of characters.



Why Do I Get "Out of Memory" Errors in the XML Parser?

We are parsing a 50Mb XML file. We have upped the java_pool_size to 150Mb with

a shared_pool_size of 200Mb. We get the following "out of memory" errors in the

Oracle XML parser:

last entry at 2000-04-26 10:59:27.042:

VisiBroker for Java runtime caught exception:

java.lang.OutOfMemoryError

at oracle.xml.parser.v2.XMLAttrList.put(XMLAttrList.java:251)

at oracle.xml.parser.v2.XMLElement.setAttribute(XMLElement.java:260)

at oracle.xml.parser.v2.XMLElement.setAttribute(XMLElement.java:228)

at cars.XMLServer.processEXL(XMLServer.java:122)



It's trying to create a new XML attribute and crashes with OutOfMemoryError.

Answer: You should not be using the DOM parser for parsing a 50Mb XML file. You

need to use the SAX parser, which parses files of arbitrary size because it does not

create an in-memory tree of nodes as it goes.

If you are using DOM, you should seriously consider moving to SAX which

processes the XML file sequentially instead of trying to build an in-memory tree

that represents the file.

Using SAX we process XML files in excess of 180Mb without any problems and

with very low memory requirements.

Rule of thumb for choosing between DOM and SAX:

DOM:



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s



DOM is very good when you need some sort of random access.



s



DOM consumes more memory.



s



DOM is also good when you are trying to transformations of some sort.



s



s



DOM is also good when you want to have tree iteration and want to walk

through the entire document tree.

See if you can use more attributes over elements in your XML (to reduce the

pipe size).



SAX:

s



SAX is good when data comes in a streaming manner (using some input

stream).



What Are the Memory Requirements for Using the PL/SQL Parser?

Answer: While the memory use is directly dependent on the document size, it

should also be realized that the PL/SQL parser uses the Java parser and thus the

Oracle JServer is being run. JServer typically requires 40-60 MB depending on its

configuration.



Is JServer (JVM) Needed to Run XML Parser for PL/SQL?

Answer: Yes, if you are running the parser in the database, you do need JServer

because the PL/SQL parser currently uses the XML Parser for Java under the

covers. JServer exists in both the Standard and Enterprise versions. A forthcoming

version of XML Parser for PL/SQL using C underneath is being developed for

applications that do not have access to a Java Virtual Machine (JVM).



Frequently Asked Questions About Using the DOM API

What Does the XML Parser for PL/SQL Do?

Answer: The XML parser accepts any XML document and gives you a tree-based

API (DOM) to access or modify the document’s elements and attributes. It also

supports XSLT which allows transformation from one XML document to another.



XML Parser for PL/SQL 20-23



Frequently Asked Questions About Using the DOM API



Can I Dynamically Set the Encoding in the XML Document?

Answer: No, you need to include the proper encoding declaration in your

document according to the specification. You cannot use

setCharset(DOMDocument) to set the encoding for the input of your document.

SetCharset(DOMDocument) is used with

oracle.xml.parser.v2.XMLDocument to set the correct encoding for the

printing.



How Do I Get the Number of Elements in a Particular Tag?

How do I get the number of elements in a tag using the Parser?

Answer: You can use the getElementByTagName (elem DOMElement, name

IN VARCHAR2) method that returns a DOMNodeList of all descent elements with a

given tag name. You can then find out the number of elements in that

DOMNodeList to determine the number of the elements in the particular tag.



How Do I Parse a String?

Answer: We do not currently have any method that can directly parse an XML

document contained within a string. You can use one of the following as a

workaround:

s



s



s



function parse (Parser, VARCHAR2) to parse XML data stored in the given

URL or the given file,

function parseBuffer (Parser, VARCHAR2) to parser XML data stored in

the given buffer, or

function parseCLOB (Parser, VARCHAR2) to parse XML data stored in the

give CLOB.



How Do I Display My XML Document?

Answer: If you are using Internet Explorer 5 as your browser, you can display the

XML document directly. Otherwise, you can use our XSLT processor in version 2 of

the parser to create the HTML document using an XSL Stylesheet. Our Java

Transviewer bean also enables you to view your XML document.



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