DescribeLayerResponse.java

/* Copyright (c) 2001 - 2007 TOPP - www.openplans.org.  All rights reserved.
 * This code is licensed under the GPL 2.0 license, availible at the root
 * application directory.
 */
package org.vfny.geoserver.wms.responses;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.nio.charset.Charset;
import java.util.HashMap;
import java.util.logging.Level;
import java.util.logging.Logger;

import javax.xml.transform.TransformerException;

import org.geoserver.config.ServiceInfo;
import org.geoserver.ows.util.RequestUtils;
import org.geoserver.platform.ServiceException;
import org.vfny.geoserver.Request;
import org.vfny.geoserver.Response;
import org.vfny.geoserver.wms.WmsException;
import org.vfny.geoserver.wms.requests.DescribeLayerRequest;
import org.vfny.geoserver.wms.responses.helpers.DescribeLayerTransformer;

/**
 * Executes a <code>DescribeLayer</code> WMS request.
 * 
 * <p>
 * Recieves a <code>DescribeLayerRequest</code> object holding the references to the requested
 * layers and utilizes a transformer based on the org.geotools.xml.transform framework to encode the
 * response.
 * </p>
 * 
 * @author Gabriel Roldan, Axios Engineering
 * @version $Id$
 */
public class DescribeLayerResponse implements Response {
    /** DOCUMENT ME! */
    private static final Logger LOGGER = org.geotools.util.logging.Logging
            .getLogger(DescribeLayerResponse.class.getPackage().getName());

    public static final String DESCLAYER_MIME_TYPE = "application/vnd.ogc.wms_xml";

    /** the request holding the required FeatureTypeInfo's */
    private DescribeLayerRequest request;

    /**
     * the transformer wich takes care of xmlencoding the DescribeLayer response
     */
    private DescribeLayerTransformer transformer;

    /** the raw XML content ready to be sent to the client */
    private byte[] content;

    /**
     * Returns any extra headers that this service might want to set in the HTTP response object.
     * 
     * @see org.vfny.geoserver.Response#getResponseHeaders()
     */
    public HashMap getResponseHeaders() {
        return null;
    }

    /**
     * DOCUMENT ME!
     * 
     * @param request
     *            DOCUMENT ME!
     * 
     * @throws ServiceException
     *             DOCUMENT ME!
     * @throws WmsException
     *             DOCUMENT ME!
     */
    public void execute(Request request) throws ServiceException {
        this.request = (DescribeLayerRequest) request;

        if (LOGGER.isLoggable(Level.FINE)) {
            LOGGER.fine(new StringBuffer("executing request ").append(request).toString());
        }

        this.transformer = new DescribeLayerTransformer(this.request.getBaseUrl());
        this.transformer.setNamespaceDeclarationEnabled(false);
        Charset encoding = this.request.getWMS().getCharSet();
        this.transformer.setEncoding(encoding);
        if (request.getServiceConfig().isVerbose()) {
            this.transformer.setIndentation(2);
        }

        ByteArrayOutputStream out = new ByteArrayOutputStream();

        try {
            transformer.transform(this.request, out);
        } catch (TransformerException e) {
            throw new WmsException(e);
        }

        this.content = out.toByteArray();
    }

    /**
     * Writes this respone to the provided output stream.
     * 
     * @param out
     *            DOCUMENT ME!
     * 
     * @throws ServiceException
     *             never.
     * @throws IOException
     *             if it is thrown while writing the response content to <code>out</code>.
     * @throws IllegalStateException
     *             if <code>execute()</code> has not been called or does not succeed (i.e.:
     *             <code>this.content ==
     *         null</code>).
     */
    public void writeTo(OutputStream out) throws ServiceException, IOException {
        if (this.content == null) {
            throw new IllegalStateException("execute() has not been called or does not succeed.");
        }

        out.write(this.content);
    }

    /**
     * Returns <code>null</code> since no special encoding is applyed to the response content.
     * 
     * @return <code>null</code>
     */
    public String getContentEncoding() {
        return null;
    }

    /**
     * @see org.vfny.geoserver.Response#getContentDisposition()
     */
    public String getContentDisposition() {
        return null;
    }

    public void abort(ServiceInfo gs) {
        // nothing to do
    }

    public String getContentType(org.geoserver.config.GeoServer gs) throws IllegalStateException {
        return DESCLAYER_MIME_TYPE;
    }
}