How to import an xquery module using Saxon

Question

I am having some troubles running an Xquery with Saxon9HE, which has a reference to an external module. I would like Saxon to resolve the module with a relative path rather absolute.

the module declaration

module namespace common = "http://my-xquery-utils";

from the main xquery

import module namespace common = "http://my-xquery-utils" at "/home/myself/common.xquery";

from my java code

public class SaxonInvocator {

private static Processor proc = null;
private static XQueryEvaluator xqe = null;
private static DocumentBuilder db = null;
private static StaticQueryContext ctx = null;

/**
 * Utility for debug, should not be called outside your IDE
 *
 * @param args xml, xqFile, xqParameter
 */
public static void main(String[] args) {
    XmlObject instance = null;
    try {
        instance = XmlObject.Factory.parse(new File(args[0]));
    } catch (XmlException ex) {
        Logger.getLogger(SaxonInvocator.class.getName()).log(Level.SEVERE, null, ex);
    } catch (IOException ex){
        Logger.getLogger(SaxonInvocator.class.getName()).log(Level.SEVERE, null, ex);
    }
    System.out.print(transform(instance, args[1], args[2]));
}

public static String transform(XmlObject input, String xqFile, String xqParameter) {
    String result = null;
    try {
        proc = new Processor(false);
        proc.getUnderlyingConfiguration().getOptimizer().setOptimizationLevel(0);
        ctx = proc.getUnderlyingConfiguration().newStaticQueryContext();
        ctx.setModuleURIResolver(new ModuleURIResolver() {

            @Override
            public StreamSource[] resolve(String moduleURI, String baseURI, String[] locations) throws XPathException {
                StreamSource[] modules = new StreamSource[locations.length];
                for (int i = 0; i < locations.length; i++) {
                    modules[i] = new StreamSource(getResourceAsStream(locations[i]));
                }
                return modules;
            }
        });

        db = proc.newDocumentBuilder();
        XQueryCompiler comp = proc.newXQueryCompiler();
        XQueryExecutable exp = comp.compile(getResourceAsStream(xqFile));
        xqe = exp.load();
        ByteArrayInputStream bais = new ByteArrayInputStream(input.xmlText().getBytes("UTF-8"));
        StreamSource ss = new StreamSource(bais);
        XdmNode node = db.build(ss);
        xqe.setExternalVariable(
                new QName(xqParameter), node);
        result = xqe.evaluate().toString();
    } catch (SaxonApiException e) {
        e.printStackTrace();
    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
    return result;
}

public static InputStream getResourceAsStream(String resource) {
    InputStream stream = SaxonInvocator.class.getResourceAsStream("/" + resource);
    if (stream == null) {
        stream = SaxonInvocator.class.getResourceAsStream(resource);
    }
    if (stream == null) {
        stream = SaxonInvocator.class.getResourceAsStream("my/project/" + resource);
    }
    if (stream == null) {
        stream = SaxonInvocator.class.getResourceAsStream("/my/project/" + resource);
    }
    return stream;
}

}

If a change it into a relative path like

import module namespace common = "http://my-xquery-utils" at "common.xquery";

I get

Error on line 22 column 1 XQST0059: java.io.FileNotFoundException

I am not sure how the ModuleURIResolver should be used.

Michael Kay Michael Kay · Accepted Answer · 2012-12-05T17:29:02

Saxon questions are best asked on the Saxon forum at http://saxonica.plan.io - questions asked here will probably be noticed eventually but sometimes, like this time, they aren't our first priority.

The basic answer is that for the relative URI to resolve, the base URI needs to be known, which means that you need to ensure that the baseURI property in the XQueryCompiler is set. This happens automatically if you compile the query from a File, but not if you compile it from an InputStream.

If you don't know a suitable base URI to set, the alternative is to write a ModuleURIResolver, which could for example fetch the module by making another call on getResourceAsStream().

How to import an xquery module using Saxon

1 Answers