Re: Problems with cached schemas

[K. Venugopal]

Hi ,

This may not solve your problem or answer your questions , but attached is a small program which i was working on , see if it is of any help.

Regards
venu

[EMAIL PROTECTED] wrote:

Hi,

Perhaps this issue has been discussed on the list but the archives aren't
available, so I have to post. Here goes...

I am trying to use what is called 'active' schema caching, as demonstrated
by the XMLGrammarBuilder example, except, I want to use DOMParser and use
the DOM of the XML instances that are successfully validated. This the code
I'm using

        SymbolTable symtab = new SymbolTable();
       XMLGrammarPreparser preparser = new XMLGrammarPreparser(symtab);
        XMLGrammarPoolImpl pool = new XMLGrammarPoolImpl();

       preparser.registerPreparser(XMLGrammarDescription.XML_SCHEMA, null);
        preparser.setProperty(GRAMMAR_POOL, pool);
        preparser.setFeature(NAMESPACES_FEATURE_ID, true);
       preparser.setFeature(VALIDATION_FEATURE_ID, true);
        preparser.setFeature(SCHEMA_VALIDATION_FEATURE_ID, true);
        preparser.setFeature(SCHEMA_FULL_CHECKING_FEATURE_ID, true);
        preparser.setErrorHandler(this);

        System.out.println("Pre-compiling Schema from file " + xsd);
        Grammar g = preparser.preparseGrammar(XMLGrammarDescription.XML_SCHEMA, 
new
XMLInputSource(null, xsd, null));
        pool.lockPool();

        XMLParserConfiguration parsercfg = new 
StandardParserConfiguration(symtab,
pool);
        parsercfg.setFeature(NAMESPACES_FEATURE_ID, true);
       parsercfg.setFeature(VALIDATION_FEATURE_ID, true);
        parsercfg.setFeature(SCHEMA_VALIDATION_FEATURE_ID, true);
        parsercfg.setFeature(SCHEMA_FULL_CHECKING_FEATURE_ID, true);
        parsercfg.setEntityResolver(new XMLEntityResolver() {
                                        public XMLInputSource
resolveEntity(XMLResourceIdentifier id) throws XNIException {
                                             System.out.println("Resolving resource: 
" +
                                             id.getLiteralSystemId());                    
                   throw new XNIException("Not resolving entity...");
                                             //return null;
                                        }
                                    });

First question is about the XMLEntityResolver. The FAQ instructs to register
a "do-nothing" EntityResolver. What does it mean? If I simply return null
(do nothing?) the XML instance document that should fail validation quietly
validates. Does it mean I should throw exception, as I do? That seems to
work but is it "do-nothing"?

More importantly, since not only need to validate XML but also get DOMs of
the valid ones, I followed the FAQ again and registered the DOMParser:

    parser = new DOMParser(parsercfg);
    parsercfg.setDocumentHandler(parser);

    ....
    // f is File
    XMLInputSource xis = new XMLInputSource(null, f.getName(), null);
    System.out.println("Parsing instance XML in file " + f.getName() + " "
+ xis.getSystemId());

    parsercfg.parse(xis);

But doe not work at all! I get a NullPointerException and the
XMLEntityResolver isn't called at all:

Pre-compiling Schema from file 2.xsd
Parsing instance XML in file 2.xml 2.xml
java.lang.NullPointerException
    at org.apache.xerces.parsers.AbstractDOMParser.startDocument(Unknown
Source)
    at org.apache.xerces.impl.xs.XMLSchemaValidator.startDocument(Unknown
Source)
    at org.apache.xerces.impl.XMLNamespaceBinder.startDocument(Unknown
    Source)     at 
org.apache.xerces.impl.dtd.XMLDTDValidator.startDocument(Unknown
    Source)     at 
org.apache.xerces.impl.XMLDocumentScannerImpl.startEntity(Unknown
Source)
    at org.apache.xerces.impl.XMLEntityManager.startEntity(Unknown Source)
    at org.apache.xerces.impl.XMLEntityManager.startDocumentEntity(Unknown
Source)
    at org.apache.xerces.impl.XMLDocumentScannerImpl.setInputSource(Unknown
Source)
    at org.apache.xerces.parsers.DTDConfiguration.parse(Unknown Source)
    [java]     at org.apache.xerces.parsers.DTDConfiguration.parse(Unknown
Source)
    at gov.treas.fms.sps.utils.SchemaVerifier.parse(SchemaVerifier.java:189)
    at gov.treas.fms.sps.utils.SchemaVerifier.parse(SchemaVerifier.java:199)
]     at
gov.treas.fms.sps.utils.SchemaVerifier.parse(SchemaVerifier.java:207)     at 
gov.treas.fms.sps.utils.SchemaVerifier.main(SchemaVerifier.java:337)

I tried to test the entity resolver of the DOMParser but it isn't called
either: parser.setEntityResolver(new EntityResolver() {
                                     public InputSource resolveEntity(String 
pubid,
String sysid) throws SAXException, IOException {
                                         System.out.println("DOM parser entity 
resolver: pub id " +
pubid + ", sysid: " + sysid);
                                         return null;
                                     }
                                 });

So, can somebody explain me what am I doing something wrong? And what should
I be doing to get what I want. Almost forgot, I'm using Xerces 2.2.1 and
changing parser with my client is very-very-very difficult - government
agency.
Please. lend a helping hand. TIA,

Regards,

-a

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