JAXB Context expects empty namespace no matter what

Question

I am facing an issue when unmarshalling an XML to my XJC Schema based generated classes using JAXB. I have read every post I've found so far, trying already who knows how many things, without success.

I have generated my Java classes using xjc -d "/myDir/src" -p nodeset.generated ./UANodeSet.xsd, where UANodeSet.xsd is this.

In my Java code, I call unmarshall the NodeSet2.xml file to the generated class UANodeSet (Root element) like:

String packageName = UANodeSet.class.getPackage().getName();
JAXBContext context = JAXBContext.newInstance(packageName);
Unmarshaller unmarshaller = context.createUnmarshaller();
unmarshaller.setEventHandler(event -> {
                System.err.println("JAXB EVENT: " + event.getMessage());
                return true; // continue after error
            });
String filePath = "C:/Users/mr/Downloads/Opc.Ua.NodeSet2.xml";
File file = new File(filePath);
JAXBElement<UANodeSet> nodeSet = (JAXBElement<UANodeSet>)unmarshaller.unmarshal(new StreamSource(file), UANodeSet.class);
UANodeSet nd = nodeSet.getValue();

This outputs the following:

JAXB EVENT: unexpected element (uri:"http://opcfoundation.org/UA/2011/03/UANodeSet.xsd", local:"Models"). Expected elements are <{}models>,<{}serverUris>,<{}extensions>,<{}aliases>,<{}namespaceUris>,<{}lastModified> 
JAXB EVENT: unexpected element (uri:"http://opcfoundation.org/UA/2011/03/UANodeSet.xsd", local:"Aliases"). Expected elements are <{}models>,<{}serverUris>,<{}extensions>,<{}aliases>,<{}namespaceUris>,<{}lastModified> 
JAXB EVENT: unexpected element (uri:"http://opcfoundation.org/UA/2011/03/UANodeSet.xsd", local:"UAObject"). Expected elements are <{}models>,<{}serverUris>,<{}extensions>,<{}aliases>,<{}namespaceUris>,<{}lastModified> 
JAXB EVENT: unexpected element (uri:"http://opcfoundation.org/UA/2011/03/UANodeSet.xsd", local:"UAObject"). Expected elements are <{}models>,<{}serverUris>,<{}extensions>,<{}aliases>,<{}namespaceUris>,<{}lastModified> 
JAXB EVENT: unexpected element (uri:"http://opcfoundation.org/UA/2011/03/UANodeSet.xsd", local:"UADataType"). Expected elements are <{}models>,<{}serverUris>,<{}extensions>,<{}aliases>,<{}namespaceUris>,<{}lastModified>

...

and nd is populated with a UANodeSet object with null values.

I confirm I have a file named package-info.java within the same package (nodeset.generated) with the following content:

@XmlSchema(
    namespace = "http://opcfoundation.org/UA/2011/03/UANodeSet.xsd",
    elementFormDefault = XmlNsForm.QUALIFIED)
package nodeset.generated;

import jakarta.xml.bind.annotation.XmlNsForm;
import jakarta.xml.bind.annotation.XmlSchema;

To have as reference, here is what UANodeSet looks like:

package nodeset.generated;

import java.util.ArrayList;
import java.util.List;
import javax.xml.datatype.XMLGregorianCalendar;
import jakarta.xml.bind.annotation.XmlAccessType;
import jakarta.xml.bind.annotation.XmlAccessorType;
import jakarta.xml.bind.annotation.XmlAttribute;
import jakarta.xml.bind.annotation.XmlElement;
import jakarta.xml.bind.annotation.XmlElements;
import jakarta.xml.bind.annotation.XmlRootElement;
import jakarta.xml.bind.annotation.XmlSchemaType;
import jakarta.xml.bind.annotation.XmlType;

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "", propOrder = {
    "namespaceUris",
    "serverUris",
    "models",
    "aliases",
    "extensions",
    "uaObjectOrUAVariableOrUAMethod"
})
@XmlRootElement(name = "UANodeSet")
public class UANodeSet {

    @XmlElement(name="NamespaceUris")
    protected UriTable namespaceUris;
    @XmlElement(name="ServerUris")
    protected UriTable serverUris;
    @XmlElement(name="Models")
    protected ModelTable models;
    @XmlElement(name="Aliases")
    protected AliasTable aliases;
    @XmlElement(name="Extensions")
    protected ListOfExtensions extensions;
    @XmlElements({
        @XmlElement(name="UAObject", type = UAObject.class),
        @XmlElement(name="UAVariable", type = UAVariable.class),
        @XmlElement(name="UAMethod", type = UAMethod.class),
        @XmlElement(name="UAView", type = UAView.class),
        @XmlElement(name="UAObjectType", type = UAObjectType.class),
        @XmlElement(name="UAVariableType", type = UAVariableType.class),
        @XmlElement(name="UADataType", type = UADataType.class),
        @XmlElement(name="UAReferenceType", type = UAReferenceType.class)
    })
    protected List<UANode> uaObjectOrUAVariableOrUAMethod;
    @XmlAttribute(name = "LastModified")
    @XmlSchemaType(name = "dateTime")
    protected XMLGregorianCalendar lastModified;

...

Things I've tried

Instantiate the JAXBContext from UANodeSet.class (JAXBContext context = JAXBContext.newInstance(UANodeSet.class);) => nothing has changed
Add manually namespace = "http://opcfoundation.org/UA/2011/03/UANodeSet.xsd" to @XmlTypes and/or @XmlElements @XmlRootElement => JAXBContext continues to say the expected elements are <{}models>,<{}serverUris>,<{}extensions>,<{}aliases>,<{}namespaceUris>,<{}lastModified>
Removing package-info.java file completely, and add the namespace="http://opcfoundation.org/UA/2011/03/UANodeSet.xsd" attribute everywhere (@XmlTypes, @XmlElements, @XmlRootElement) => no changes.

Basically, I cannot make my JAXBContext expect the proper namespace for the UANodeSet elements.

Any help is appreciated, I have been fighting with this since too long already.

Use code block format for the error too. Quote format makes it lose the structure and is less readable. — aled
– aled, Commented Apr 9 at 2:15

Miguel · Accepted Answer · 2025-04-09 21:11:57Z

1

Well, I cannot really explain why because I lack years of experience with Java and Plug-in Development Environment, but the problem seems to be that my XML unmarshalling is in a different plug-in as my generated classes.

If I create my JAXBContext from ObjectFactory.class in a plug-in project different from where the package nodeset.generated is defined (package that holds the XJC generated classes), then the context doesn't know about UANodeSet class. I find it strange, because nodeset.generated is being exported, and imported in the unmarshalling package.

I have moved the unmarshalling methods to nodeset.generated and everything worked like charm.

If someone can give the details on why this could be, I will happily edit this answer.

answered Apr 9 at 21:11

Miguel

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Comments

Kevin Herron · Accepted Answer · 2025-04-09 07:34:37Z

0

While not a direct answer to your question, I am currently using XJC and JAXB on the exact same schema in this project: https://github.com/digitalpetri/uanodeset

I use jaxb2-maven-plugin as configured here: https://github.com/digitalpetri/uanodeset/blob/ec3c182f0c808667994951c19f1c7d2b42c46c92/uanodeset-core/pom.xml#L55-L91

Parsing the UANodeSet XML file is simply:

/**
 * Read and parse an XML document conforming to the <a
 * href="http://opcfoundation.org/UA/2011/03/UANodeSet.xsd">UANodeSet</a> schema from an {@link
 * InputStream}.
 *
 * @param inputStream the {@link InputStream} to read from.
 * @return a {@link UANodeSet}.
 * @throws JAXBException if an error occurs while unmarshalling.
 */
public static UANodeSet parse(InputStream inputStream) throws JAXBException {
  JAXBContext jaxbContext = JAXBContext.newInstance(ObjectFactory.class);

  return (UANodeSet) jaxbContext.createUnmarshaller().unmarshal(inputStream);
}

If you can't use my project, maybe you can at least re-use some of the code.

edited Apr 9 at 7:34

answered Apr 8 at 23:59

Kevin Herron

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5 Comments

Miguel Apr 9 at 17:25

How does your ObjectFactory class look like? If I use your code, I get the following error:

jakarta.xml.bind.UnmarshalException: unexpected element (uri:"http://opcfoundation.org/UA/2011/03/UANodeSet.xsd", local:"UANodeSet"). Expected elements are (none)

Kevin Herron Apr 9 at 18:31

gist.github.com/kevinherron/07ae95612b1241494cd7ccf8dff3d71a if you check out and build the project you'll be able to inspect all of the generated sources.

Miguel Apr 9 at 18:40

thanks! all the classes look exactly the same.. Still don't know why it's not working on my project. I am not using Maven, I am using OSGI. I am new to Java, so I honestly don't know what could the differences be

Kevin Herron Apr 9 at 19:16

Although I am not an OSGI user, I do know enough to tell you that Maven and OSGI are orthogonal. Maven is a build tool, whereas OSGI is kind of a framework for building modular applications. I don't know why it doesn't work for you in your environment though. Maybe different versions of the JAXB / XML bind API dependencies?

Miguel Apr 9 at 20:17

Myself I am using JAXB downloaded from here: eclipse-ee4j.github.io/jaxb-ri Have grabbed the .jar files at /mod and added them to a folder called /lib inside my PDE project. Then I've added them to the classpath, and compile works. But then I get the errors explained in the post

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