RSSExceptionTransformer.java

/* (c) 2017 Open Source Geospatial Foundation - all rights reserved
 * This code is licensed under the GPL 2.0 license, available at the root
 * application directory.
 */
package org.geoserver.opensearch.eo.response;

import static org.geoserver.ows.util.ResponseUtils.baseURL;
import static org.geoserver.ows.util.ResponseUtils.buildURL;

import java.io.ByteArrayOutputStream;
import java.io.PrintStream;

import org.geoserver.config.GeoServerInfo;
import org.geoserver.ows.Request;
import org.geoserver.ows.URLMangler.URLType;
import org.geoserver.ows.util.OwsUtils;
import org.geoserver.ows.util.ResponseUtils;
import org.geoserver.platform.ServiceException;
import org.geotools.xml.transform.Translator;
import org.xml.sax.ContentHandler;

/**
 * Based on the indications at http://www.opensearch.org/Documentation/Developer_how_to_guide#How_to_indicate_errors encodes the exception into a RSS
 * document, e.g.
 * 
 * <pre>
 * {@code
 * <rss version="2.0" xmlns:openSearch="http://a9.com/-/spec/opensearch/1.1/">
   <channel>
     <title>title</title>
     <link>link</link>
     <description>description</description>
     <openSearch:totalResults>1</openSearch:totalResults>
     <openSearch:startIndex>1</openSearch:startIndex>
     <openSearch:itemsPerPage>1</openSearch:itemsPerPage>
     <item>
       <title>Error</title>
       <description>error message</description>
     </item>
   </channel>
}
 * </pre>
 *
 * @author Andrea Aime - GeoSolutions
 */
public class RSSExceptionTransformer extends LambdaTransformerBase {

    Request request;

    GeoServerInfo geoServer;

    public RSSExceptionTransformer(GeoServerInfo geoServer, Request request) {
        this.request = request;
        this.geoServer = geoServer;
    }

    @Override
    public Translator createTranslator(ContentHandler handler) {
        return new ExceptionTranslator(handler);
    }
    
    public static String getDescription(GeoServerInfo geoServer, ServiceException e) {
        StringBuffer sb = new StringBuffer();
        OwsUtils.dumpExceptionMessages(e, sb, true);

        if (geoServer.getSettings().isVerboseExceptions()) {
            ByteArrayOutputStream stackTrace = new ByteArrayOutputStream();
            e.printStackTrace(new PrintStream(stackTrace));

            sb.append("\nDetails:\n");
            sb.append(ResponseUtils.encodeXML(new String(stackTrace.toByteArray())));
        }

        return sb.toString();
    }

    class ExceptionTranslator extends LambdaTranslatorSupport {

        public ExceptionTranslator(ContentHandler contentHandler) {
            super(contentHandler);
        }

        @Override
        public void encode(Object o) throws IllegalArgumentException {
            ServiceException e = (ServiceException) o;
            element("rss", () -> channel(e), //
                    attributes("xmlns:opensearch", "http://a9.com/-/spec/opensearch/1.1/"));

        }

        private void channel(ServiceException e) {
            element("channel", () -> {
                element("title", "OpenSearch for EO Error report");
                element("link", buildSelfUrl());
                element("opensearch:totalResults", "1");
                element("opensearch:startIndex", "1");
                element("opensearch:itemsPerPage", "1");
                element("item", () -> itemContents(e));
            });
        }

        private void itemContents(ServiceException e) {
            element("title", e.getMessage());
            element("description", getDescription(geoServer, e));
        }

        private String buildSelfUrl() {
            String baseURL = baseURL(request.getHttpRequest());
            return buildURL(baseURL, "oseo/description", null, URLType.SERVICE);
        }

    }

}