PortfolioPublishServlet xref

    1   /***
    2    *
    3    * Copyright 2004 Protique Ltd
    4    *
    5    * Licensed under the Apache License, Version 2.0 (the "License");
    6    * you may not use this file except in compliance with the License.
    7    * You may obtain a copy of the License at
    8    *
    9    * http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the License for the specific language governing permissions and
    15   * limitations under the License.
    16   *
    17   **/
    18  package org.codehaus.activemq.web;
    19
    20  import javax.jms.Destination;
    21  import javax.jms.JMSException;
    22  import javax.jms.Message;
    23  import javax.jms.Session;
    24  import javax.servlet.ServletException;
    25  import javax.servlet.http.HttpServletRequest;
    26  import javax.servlet.http.HttpServletResponse;
    27  import java.io.IOException;
    28  import java.io.PrintWriter;
    29  import java.util.Hashtable;
    30  import java.util.Map;
    31
    32  /***
    33   * A servlet which will publish dummy market data prices
    34   *
    35   * @version $Revision: 1.1 $
    36   */
    37  public class PortfolioPublishServlet extends MessageServletSupport {
    38
    39      private static final int maxDeltaPercent = 1;
    40      private static final Map lastPrices = new Hashtable();
    41
    42      protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    43          PrintWriter out = response.getWriter();
    44          String[] stocks = request.getParameterValues("stocks");
    45          if (stocks == null || stocks.length == 0) {
    46              out.println("<html><body>No <b>stocks</b> query parameter specified. Cannot publish market data</body></html>");
    47          } else {
    48              int count = getNumberOfMessages(request);
    49              try {
    50                  WebClient client = getWebClient(request);
    51                  for (int i = 0; i < count; i++) {
    52                      sendMessage(client, stocks);
    53                  }
    54                  out.println("<html><head><meta http-equiv='refresh' content='1'/></head>");
    55                  out.println("<body>Published <b>" + count + "</b> price messages");
    56                  out.println("</body></html>");
    57
    58              } catch (JMSException e) {
    59                  out.println("<html><body>Failed sending price messages due to <b>" + e + "</b></body></html>");
    60                  log("Failed to send message: " + e, e);
    61              }
    62          }
    63      }
    64
    65      protected void sendMessage(WebClient client, String[] stocks) throws JMSException {
    66          Session session = client.getSession();
    67
    68          int idx = 0;
    69          while (true) {
    70              idx = (int) Math.round(stocks.length * Math.random());
    71              if (idx < stocks.length) {
    72                  break;
    73              }
    74          }
    75          String stock = stocks[idx];
    76          Destination destination = session.createTopic("STOCKS." + stock);
    77          String stockText = createStockText(stock);
    78          log("Sending: " + stockText);
    79          Message message = session.createTextMessage(stockText);
    80          client.send(destination, message);
    81      }
    82
    83      protected String createStockText(String stock) {
    84          Double value = (Double) lastPrices.get(stock);
    85          if (value == null) {
    86              value = new Double(Math.random() * 100);
    87          }
    88
    89          // lets mutate the value by some percentage
    90          double oldPrice = value.doubleValue();
    91          value = new Double(mutatePrice(oldPrice));
    92          lastPrices.put(stock, value);
    93          double price = value.doubleValue();
    94
    95          double offer = price * 1.001;
    96          String movement = (price > oldPrice) ? "up" : "down";
    97          return "<price stock='" + stock + "' bid='" + price + "' offer='" + offer + "' movement='" + movement + "'/>";
    98
    99      }
    100
    101     protected double mutatePrice(double price) {
    102         double percentChange = (2 * Math.random() * maxDeltaPercent) - maxDeltaPercent;
    103
    104         return price * (100 + percentChange) / 100;
    105     }
    106
    107     protected int getNumberOfMessages(HttpServletRequest request) {
    108         String name = request.getParameter("count");
    109         if (name != null) {
    110             return Integer.parseInt(name);
    111         }
    112         return 1;
    113     }
    114 }