Exception while decoding using SAXTransmogrifier

[Martin Bobak]

We are using javax.xml.transform.Transformer for encoding and decoding xml. Encoding is done without any errors, but when decoding exi we got exception :

ERROR: ''
javax.xml.transform.TransformerException: java.lang.NullPointerException
at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.transform(TransformerImpl.java:755)

When there is GrammarOptions.addNS(go) option used, exception is :

org.w3c.dom.DOMException: NAMESPACE_ERR: An attempt is made to create or change an object in a way which is incorrect with regard to namespaces.

this code snippet shows how encoding is done :

    final Transmogrifier transmogrifier = new Transmogrifier();

    transmogrifier.setAlignmentType(AlignmentType.bitPacked);

    final ByteArrayOutputStream out = new ByteArrayOutputStream();

    transmogrifier.setGrammarCache(getGrammarCache());

    transmogrifier.setOutputStream(out);

    transmogrifier.encode(new InputSource(new ByteArrayInputStream(toString(xml, false).getBytes())));

    out.flush();

    return out.toByteArray();

code snippet for decoding :

    try(ByteArrayInputStream in = new ByteArrayInputStream(input)) {

        final EXIReader reader = new EXIReader();

        reader.setAlignmentType(AlignmentType.bitPacked);
        grammarCache = getGrammarCache();

        reader.setGrammarCache(grammarCache);

        final SAXTransformerFactory transformerFactory
                = (SAXTransformerFactory) TransformerFactory.newInstance();
        SAXParserFactory saxParserFactory = SAXParserFactory.newInstance();
        saxParserFactory.setNamespaceAware(true);
        final TransformerHandler handler = transformerFactory.newTransformerHandler();
        handler.setResult(domResult);

        reader.setContentHandler(handler);

        reader.parse(new InputSource(in));
    }

code snippet grammar options used :

   private static GrammarCache getGrammarCache() {
        short go = GrammarOptions.DEFAULT_OPTIONS;

        // This option on or off, nagasena still fails
        go = GrammarOptions.addNS(go);

        return new GrammarCache(null, go);
    }

[Takuki Kamiya]

Hi,

Can you send me the XML and schema files that were used?

taki

[Martin Bobak]

This is xml used for testing :

<abc:rpc message-id="id" xmlns:abc="a.b.c">
<abc:inner/>
</abc:rpc>

it is generated from Element object constructed by method getDom :

public static Element getDom() {
    final Element dom;
    final Document d = newDocument();
    dom = d.createElementNS("a.b.c", "abc:rpc");
    dom.setAttribute("message-id", "id");
    Element innerElement = d.createElement("abc:inner");
    dom.appendChild(innerElement);
    return dom;
}

[Martin Bobak]

I discovered so far that javax.xml.transform.TransformerException: java.lang.NullPointerException is caused by Transmogrifier$SAXEventHandler#verifyPrefix in which new Locator is created using copy constructor with m_locator as argument which is null. There seems to be issue related to uri extracted from prefix.

[Takuki Kamiya]

I added a test case "testToDOM_01" in XmlSerializationTest.java.
The test case basically does what you described.

Can you retrieve the source and tests, and run the unit tests?

You can export nagasena by:
$ svn export https://svn.code.sf.net/p/openexi/code/trunk/nagasena

Unit tests can be run by:
$ ant clean; ant test

[Martin Bobak]

Test fails when Transformer javax.xml.transform.Transformer is used for encoding exi. Here is code snippet how we are using it :

    final Transmogrifier transmogrifier = new Transmogrifier();
    transmogrifier.setAlignmentType(AlignmentType.bitPacked);
    final ByteArrayOutputStream out = new ByteArrayOutputStream();
    transmogrifier.setGrammarCache(getGrammarCache());
    transmogrifier.setOutputStream(out);
    final Transformer transformer = saxTransformerFactory.newTransformer();
    transformer.transform(new DOMSource(xml), new SAXResult(transmogrifier.getSAXTransmogrifier()));
    byte[] bts = out.toByteArray();

[Takuki Kamiya]

In your initial report, you said "Encoding is done without any errors, but when decoding exi we got exception". That's what I investigated. Also, the test I implemented was about the decoding, which I verified works. Was that statement bogus?

[Takuki Kamiya]

Please give precise description to your report next time.
I believe I fixed this issue in the latest Nagasena.

[Martin Bobak]

I'm sorry for misleading you. My bad. But error happend during decoding only when exi was encoded using Transformer.

[Takuki Kamiya]

Thanks for finding the issue.