de.decoit.visa.http.ajax.handlers.RequestTopologyHandler.java Source code

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Here is the source code for de.decoit.visa.http.ajax.handlers.RequestTopologyHandler.java

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/*
 *  Copyright (C) 2013, DECOIT GmbH
 *
 *   This file is part of VISA Topology-Editor.
 *
 *   VISA Topology-Editor is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by the
 *   Free Software Foundation, either version 3 of the License, or (at your option)
 *   any later version.
 *
 *   VISA Topology-Editor 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 General Public License for
 *   more details.
 *
 *   You should have received a copy of the GNU General Public License along with
 *   VISA Topology-Editor. If not, see <http://www.gnu.org/licenses/>.
 */

package de.decoit.visa.http.ajax.handlers;

import java.io.IOException;
import org.apache.log4j.Logger;
import org.json.JSONException;
import org.json.JSONObject;
import com.sun.net.httpserver.HttpExchange;
import de.decoit.visa.TEBackend;
import de.decoit.visa.http.ajax.AJAXServer;

/**
 * This handler tells the {@link de.decoit.visa.topology.TopologyStorage} to generate a JSON object of
 * the current topology.<br>
 * <br>
 * On success, the generated JSON object will be returned (key: topology).<br>
 * <br>
 * Any exception thrown during the processing of the request will cause the
 * request to fail. <br>
 * Possible return messages of this handler are:<br>
 * - ajaxSuccess (success)<br>
 * - ajaxException (exception caught and no recovery attempt made)<br>
 *
 * @author Thomas Rix
 * @see AJAXServer
 * @see DefaultHandler
 */
public class RequestTopologyHandler extends DefaultHandler {
    private static Logger log = Logger.getLogger(RequestTopologyHandler.class.getName());

    @Override
    public void handle(HttpExchange he) throws IOException {
        log.info(he.getRequestURI().toString());

        String response;
        try {
            JSONObject rv = new JSONObject();
            rv.put("status", AJAXServer.AJAX_SUCCESS);
            rv.put("topology", TEBackend.TOPOLOGY_STORAGE.genTopologyJSON());
            response = rv.toString();
        } catch (Throwable ex) {
            TEBackend.logException(ex, log);

            JSONObject rv = new JSONObject();
            try {
                rv.put("status", AJAXServer.AJAX_ERROR_EXCEPTION);
                rv.put("type", ex.getClass().getSimpleName());
                rv.put("message", ex.getMessage());
            } catch (JSONException exc) {
                /* Ignore */
            }

            response = rv.toString();
        }

        // Send the response headers
        sendResponse(he, response);
    }
}