I am writing a RESTFUL web service in Java. The idea is to "cut down" an XML document and strip away all the un-needed content (~98%) and leave only the tags we're interested in, while maintaining the document's structure, which is as follows (I cannot provide the actual XML content for confidentiality reasons):
<sear:SEGMENTS xmlns="http://www.exlibrisgroup.com/xsd/primo/primo_nm_bib" xmlns:sear="http://www.exlibrisgroup.com/xsd/jaguar/search">
<sear:JAGROOT>
<sear:RESULT>
<sear:DOCSET IS_LOCAL="true" TOTAL_TIME="176" LASTHIT="9" FIRSTHIT="0" TOTALHITS="262" HIT_TIME="11">
<sear:DOC SEARCH_ENGINE_TYPE="Local Search Engine" SEARCH_ENGINE="Local Search Engine" NO="1" RANK="0.086826384" ID="2347460">
[
<PrimoNMBib>
<record>
<display>
<title></title>
</display>
<sort>
<author></author>
</sort>
</record>
</PrimoNMBib>
]
</sear:DOC>
</sear:DOCSET>
</sear:RESULT>
</sear:JAGROOT>
</sear:SEGMENTS>
Of course, this is the structure of only the tags we are interested in - there are hundreds more tags, but they are irrelevant.
The square brackets ([]) are not part of the XML and indicate that the element are elements of a list of children and occur more than once - one per match of the search from the RESTFUL service.
This being said, my Java code containing the XSLT stylesheet is as follows:
import java.io.StringReader;
import java.io.StringWriter;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.TransformerFactoryConfigurationError;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.stream.StreamSource;
public String cutXML() throws TransformerFactoryConfigurationError, TransformerException
{
String xmlSourceResource = this.xml; // where this.xml is the full XML string of structure as presented above
String xsltResource =
"<xsl:stylesheet version=\"1.0\" xmlns:xsl=\"http://www.w3.org/1999/XSL/Transform\" xmlns:sear=\"http://www.exlibrisgroup.com/xsd/jaguar/search\">" +
" <xsl:output method=\"xml\" version=\"1.0\" omit-xml-declaration=\"no\" encoding=\"UTF-8\" indent=\"yes\"/>" +
" <xsl:strip-space elements=\"*\"/>" +
" <sear:WhiteList>" +
" <name>title</name>" +
" <name>author</name>" +
" </sear:WhiteList>" +
" <xsl:template match=\"node()|@*\">" +
" <xsl:copy>" +
" <xsl:apply-templates select=\"node()|@*\"/>" +
" </xsl:copy>" +
" </xsl:template>" +
" <xsl:template match=\"*[not(descendant-or-self::*[name()=document('')/*/sear:WhiteList/*])]\"/>" +
"</xsl:stylesheet>";
StringWriter xmlResultResource = new StringWriter(); // where the transformed/stripped-down XML will be written
Transformer xmlTransformer = TransformerFactory.newInstance().newTransformer(new StreamSource(new StringReader(xsltResource))); // create transformer object with XSLT given
xmlTransformer.transform(new StreamSource(new StringReader(xmlSourceResource)), new StreamResult(xmlResultResource)); // transform XML with transformer and write into result StringWriter
return xmlResultResource.getBuffer().toString(); // return transformed XML string
}
Unfortunately, when I run it on the server, all I get is an empty page with an empty source, as if the result of the transformation was an empty String.
The server's log file first gave the following information:
[#|2012-04-26T18:26:24.967+0000|INFO|glassfish3.1.2|com.sun.jersey.api.core.PackagesResourceConfig|_ThreadID=23;_ThreadName=Thread-2;|Scanning for root resource and provider classes in the packages: dk.kb.mobileservice|#]
[#|2012-04-26T18:26:24.969+0000|INFO|glassfish3.1.2|com.sun.jersey.api.core.ScanningResourceConfig|_ThreadID=23;_ThreadName=Thread-2;|Root resource classes found: class dk.kb.mobileservice.Middle|#]
[#|2012-04-26T18:26:24.970+0000|INFO|glassfish3.1.2|com.sun.jersey.api.core.ScanningResourceConfig|_ThreadID=23;_ThreadName=Thread-2;|No provider classes found.|#]
[#|2012-04-26T18:26:24.978+0000|INFO|glassfish3.1.2|com.sun.jersey.server.impl.application.WebApplicationImpl|_ThreadID=23;_ThreadName=Thread-2;|Initiating Jersey application, version 'Jersey: 1.11 12/09/2011 10:27 AM'|#]
[#|2012-04-26T18:26:25.192+0000|INFO|glassfish3.1.2|javax.enterprise.system.container.web.com.sun.enterprise.web|_ThreadID=23;_ThreadName=Thread-2;|WEB0671: Loading application [kb2] at [/kb2]|#]
[#|2012-04-26T18:26:25.200+0000|INFO|glassfish3.1.2|javax.enterprise.system.tools.admin.org.glassfish.deployment.admin|_ThreadID=23;_ThreadName=Thread-2;|kb2 was successfully deployed in 2,293 milliseconds.|#]
[#|2012-04-26T18:26:46.263+0000|SEVERE|glassfish3.1.2|javax.enterprise.system.std.com.sun.enterprise.server.logging|_ThreadID=20;_ThreadName=Thread-2;|SystemId Unknown; Line #0; Column #0; java.lang.NullPointerException |#]
[#|2012-04-26T18:31:09.772+0000|SEVERE|glassfish3.1.2|javax.enterprise.system.std.com.sun.enterprise.server.logging|_ThreadID=21;_ThreadName=Thread-2;|SystemId Unknown; Line #0; Column #0; java.lang.NullPointerException |#]
and now it returns the following issues:
[#|2012-04-27T00:05:07.731+0000|SEVERE|glassfish3.1.2|javax.enterprise.system.std.com.sun.enterprise.server.logging|_ThreadID=21;_ThreadName=Thread-2;|Error on line 1 column 1 of file:/root/webglassfish3/glassfish/domains/domain1/config/: SXXP0003: Error reported by XML parser: Content is not allowed in prolog.|#]
[#|2012-04-27T00:05:07.732+0000|SEVERE|glassfish3.1.2|javax.enterprise.system.std.com.sun.enterprise.server.logging|_ThreadID=21;_ThreadName=Thread-2;|Recoverable error on line 1 SXXP0003: org.xml.sax.SAXParseException: Content is not allowed in prolog.|#]
I've tested the XML file and transformed it via browser, and it worked, so I don't think it's the XML's nor the XSLT stylesheet's fault... It seems to be a Java issue.
When I run the above Java code on the entire XML outside of GlassFish, I get the following errors:
Exception in thread "main" java.lang.VerifyError: (class: GregorSamsa$0, method: test signature: (IIIILcom/sun/org/apache/xalan/internal/xsltc/runtime/AbstractTranslet;Lcom/sun/org/apache/xml/internal/dtm/DTMAxisIterator;)Z) Incompatible type for getting or setting field
at GregorSamsa.applyTemplates()
at GregorSamsa.applyTemplates()
at GregorSamsa.transform()
at com.sun.org.apache.xalan.internal.xsltc.runtime.AbstractTranslet.transform(AbstractTranslet.java:609)
at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.transform(TransformerImpl.java:729)
at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.transform(TransformerImpl.java:340)
at XML2JSON.cutXML(XML2JSON.java:105)
at XML2JSON.main(XML2JSON.java:31)
