Java tutorial
/* * 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 java.util.HashMap; import org.apache.log4j.Logger; import org.json.JSONException; import org.json.JSONObject; import org.w3c.dom.Document; import org.w3c.dom.Element; import org.w3c.dom.Node; import org.w3c.dom.NodeList; import com.sun.net.httpserver.HttpExchange; import de.decoit.visa.TEBackend; import de.decoit.visa.http.QueryString; import de.decoit.visa.http.ajax.AJAXServer; /** * This HttpHandler implementation handles requests to import a VSA template * into the existing topology.<br> * <br> * On success, a JSON object will be returned containing the JSON object of the * current topology (key: topology)<br> * <br> * Any exception thrown during the processing of the request will cause the * request to fail. One attempt to recover the topology from the exception is * made. If that fails, the topology and RDF model will be cleared.<br> * <br> * Possible return messages of this handler are:<br> * - ajaxSuccess (success)<br> * - ajaxException (exception caught but recovered)<br> * - ajaxExceptionUnresolved (exception caught and recovery not possible)<br> * - ajaxMissing (missing arguments) * * @author Thomas Rix * @see AJAXServer * @see DefaultHandler */ public class CreateVSAHandler extends DefaultHandler { private static Logger log = Logger.getLogger(ConfigureHandler.class.getName()); @Override public void handle(HttpExchange he) throws IOException { log.info(he.getRequestURI().toString()); // Get the URI of the request and extract the query string from it QueryString queryParameters = new QueryString(he.getRequestURI()); // Create StringBuilder for the response String response = null; // Check if the query parameters are valid for this handler if (this.checkQueryParameters(queryParameters)) { try { HashMap<String, String> connTargets = new HashMap<>(); HashMap<String, String> connVLANs = new HashMap<>(); boolean connParamsPresent = true; Document tpl = TEBackend.RDF_MANAGER .getVSATemplate(Integer.parseInt(queryParameters.get("tplid").get())); // Verify that all connections are present in the query // parameters // Get all elements of type CONNECTION and iterate over the list NodeList nl = tpl.getElementsByTagName("CONNECTION"); for (int i = 0; i < nl.getLength(); i++) { Node n = nl.item(i); // Check if the node is an Element. Should be the case, just // for security reasons if (n.getNodeType() == Node.ELEMENT_NODE) { // Cast the node to Element to access the attributes Element e = (Element) n; String id = e.getAttribute("id"); if (!queryParameters.containsKey(id)) { // A connection is missing, set the response to the // missing arguments message and break the loop connParamsPresent = false; JSONObject rv = new JSONObject(); rv.put("status", AJAXServer.AJAX_ERROR_MISSING_ARGS); response = rv.toString(); break; } else { connTargets.put(id, queryParameters.get(id).get()); StringBuilder sbVLAN = new StringBuilder(id); sbVLAN.append("_vlan"); if (queryParameters.containsKey(sbVLAN.toString())) { connVLANs.put(id, queryParameters.get(sbVLAN.toString()).get()); } } } } if (connParamsPresent) { TEBackend.RDF_MANAGER.importRDFTemplate(Integer.parseInt(queryParameters.get("tplid").get()), queryParameters.get("name").get(), connTargets, connVLANs); // Return success response 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); try { // Synchronize the topology with the RDF model to // resolve // any errors caused by the caught exception TEBackend.RDF_MANAGER.syncTopologyToRDF(); JSONObject rv = new JSONObject(); rv.put("status", AJAXServer.AJAX_ERROR_EXCEPTION); rv.put("type", ex.getClass().getSimpleName()); rv.put("message", ex.getMessage()); rv.put("topology", TEBackend.TOPOLOGY_STORAGE.genTopologyJSON()); response = rv.toString(); } catch (Throwable e) { // Exception during synchronization, the model may have // been // corrupted so the whole backend was cleared JSONObject rv = new JSONObject(); try { rv.put("status", AJAXServer.AJAX_ERROR_EXCEPTION_UNRESOLVED); rv.put("topology", TEBackend.TOPOLOGY_STORAGE.genTopologyJSON()); } catch (JSONException exc) { /* Ignore */ } response = rv.toString(); } } } else { // Missing or malformed query string, set response to error code JSONObject rv = new JSONObject(); try { // Missing or malformed query string, set response to error code rv.put("status", AJAXServer.AJAX_ERROR_MISSING_ARGS); } catch (JSONException exc) { /* Ignore */ } response = rv.toString(); } // Send the response sendResponse(he, response); } /** * Check if the provided QueryString object contains all keys required by * this handler and if their values are valid. * * @param pQueryString A QueryString object with all query parameters of the * request * @return true if no problems were found, false if something is missing or * malformed */ private boolean checkQueryParameters(QueryString pQueryString) { boolean rv = true; if (rv && (!pQueryString.containsKey("tplid") || !pQueryString.get("tplid").get().matches("\\d+"))) { rv = false; } if (rv && (!pQueryString.containsKey("name") || pQueryString.get("name").get().isEmpty())) { rv = false; } return rv; } }