org.yawlfoundation.yawl.resourcing.codelets.XQueryEvaluator.java Source code

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Here is the source code for org.yawlfoundation.yawl.resourcing.codelets.XQueryEvaluator.java

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/*
 * Copyright (c) 2004-2012 The YAWL Foundation. All rights reserved.
 * The YAWL Foundation is a collaboration of individuals and
 * organisations who are committed to improving workflow technology.
 *
 * This file is part of YAWL. YAWL is free software: you can
 * redistribute it and/or modify it under the terms of the GNU Lesser
 * General Public License as published by the Free Software Foundation.
 *
 * YAWL is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
 * Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with YAWL. If not, see <http://www.gnu.org/licenses/>.
 */

package org.yawlfoundation.yawl.resourcing.codelets;

import net.sf.saxon.s9api.SaxonApiException;
import org.jdom2.Document;
import org.jdom2.Element;
import org.yawlfoundation.yawl.elements.data.YParameter;
import org.yawlfoundation.yawl.util.SaxonUtil;

import java.util.List;
import java.util.ArrayList;

/**
 * @author Michael Adams
 * Creation Date: 30/04/2008
 */
public class XQueryEvaluator extends AbstractCodelet {

    public XQueryEvaluator() {
        super();
        setDescription("This codelet executes an XQuery. Required parameters:<br> "
                + "Input: query (type String, required): the XQuery<br>"
                + " &nbsp;&nbsp; plus other values used by the XQuery<br>" + "Output: result (type String)");
    }

    public Element execute(Element inData, List<YParameter> inParams, List<YParameter> outParams)
            throws CodeletExecutionException {

        if (outParams == null) {
            String msg = "Cannot perform evaluation: Missing or empty output parameter list.";
            throw new CodeletExecutionException(msg);
        }

        this.setInputs(inData, inParams, outParams);

        // convert input vars to a Doc
        Document dataDoc = new Document(inData.clone());

        String query = (String) getParameterValue("query");
        String output = evaluateQuery(query, dataDoc);

        setParameterValue("result", output);
        return getOutputData();
    }

    private String evaluateQuery(String query, Document dataDoc) throws CodeletExecutionException {

        try {
            String result = SaxonUtil.evaluateQuery(query, dataDoc);
            if (result != null)
                return result;
            else
                throw new CodeletExecutionException("No data produced for query: '" + query + "'.");
        } catch (SaxonApiException sapie) {
            throw new CodeletExecutionException(
                    "Invalid query: '" + query + "'.\n" + "Message from parser: [" + sapie.getMessage() + "]");
        } catch (Exception e) {
            throw new CodeletExecutionException("Exception in query evaluation: '" + query + "'.");
        }
    }

    public List<YParameter> getRequiredParams() {
        List<YParameter> params = new ArrayList<YParameter>();

        YParameter param = new YParameter(null, YParameter._INPUT_PARAM_TYPE);
        param.setDataTypeAndName("string", "query", XSD_NAMESPACE);
        param.setDocumentation("The XQuery to evaluate");
        params.add(param);

        param = new YParameter(null, YParameter._OUTPUT_PARAM_TYPE);
        param.setDataTypeAndName("string", "result", XSD_NAMESPACE);
        param.setDocumentation("The result of the evaluation");
        params.add(param);
        return params;
    }

}