1 | // Copyright 2012 Georg-August-Universität Göttingen, Germany |
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2 | // |
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3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
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4 | // you may not use this file except in compliance with the License. |
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5 | // You may obtain a copy of the License at |
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6 | // |
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7 | // http://www.apache.org/licenses/LICENSE-2.0 |
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8 | // |
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9 | // Unless required by applicable law or agreed to in writing, software |
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10 | // distributed under the License is distributed on an "AS IS" BASIS, |
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11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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12 | // See the License for the specific language governing permissions and |
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13 | // limitations under the License. |
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14 | |
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15 | package de.ugoe.cs.autoquest.httpmonitor.proxy; |
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16 | |
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17 | import java.util.logging.Level; |
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18 | |
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19 | import org.eclipse.jetty.client.api.Request; |
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20 | import org.eclipse.jetty.client.api.Result; |
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21 | import org.eclipse.jetty.client.api.Response.CompleteListener; |
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22 | import org.eclipse.jetty.http.HttpMethod; |
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23 | import org.eclipse.jetty.http.HttpVersion; |
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24 | |
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25 | import de.ugoe.cs.autoquest.httpmonitor.HttpMonitorComponent; |
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26 | import de.ugoe.cs.autoquest.httpmonitor.HttpMonitorException; |
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27 | import de.ugoe.cs.autoquest.httpmonitor.IdGenerator; |
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28 | import de.ugoe.cs.autoquest.httpmonitor.SimpleIdGenerator; |
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29 | import de.ugoe.cs.util.console.Console; |
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30 | |
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31 | /** |
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32 | * <p> |
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33 | * if a central monitoring server is used by the proxy, then this id generator is a connection to |
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34 | * the server to receive centrally unique ordering ids from the central server. If the central |
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35 | * server cannot be reached, this id generated uses a fallback internal {@link SimpleIdGenerator}. |
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36 | * </p> |
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37 | * |
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38 | * @author Patrick Harms |
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39 | */ |
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40 | public class HttpMonitorRemoteIdGenerator |
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41 | extends HttpMonitorRemoteConnection |
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42 | implements CompleteListener, IdGenerator, HttpMonitorComponent |
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43 | { |
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44 | /** the fall back id generator used internally if the server is not reachable*/ |
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45 | private IdGenerator fallBackIdGenerator = new SimpleIdGenerator(); |
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46 | |
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47 | /** |
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48 | * <p> |
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49 | * initializes the id generator with the host and port of the central server from which to |
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50 | * retrieve the ids |
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51 | * </p> |
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52 | * |
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53 | * @param httpMonitorServer the host name of the central server |
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54 | * @param httpMonitorPort the port of the central server |
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55 | */ |
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56 | public HttpMonitorRemoteIdGenerator(String httpMonitorServer, int httpMonitorPort) { |
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57 | super(httpMonitorServer, httpMonitorPort); |
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58 | } |
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59 | |
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60 | /* (non-Javadoc) |
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61 | * @see de.ugoe.cs.autoquest.httpmonitor.proxy.HttpMonitorRemoteConnection#init() |
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62 | */ |
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63 | @Override |
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64 | public void init() throws IllegalStateException, HttpMonitorException { |
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65 | fallBackIdGenerator.init(); |
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66 | super.init(); |
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67 | } |
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68 | |
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69 | /* (non-Javadoc) |
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70 | * @see de.ugoe.cs.autoquest.httpmonitor.proxy.HttpMonitorRemoteConnection#start() |
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71 | */ |
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72 | @Override |
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73 | public void start() throws IllegalStateException, HttpMonitorException { |
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74 | fallBackIdGenerator.start(); |
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75 | super.start(); |
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76 | } |
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77 | |
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78 | /* (non-Javadoc) |
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79 | * @see de.ugoe.cs.autoquest.httpmonitor.proxy.HttpMonitorRemoteConnection#stop() |
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80 | */ |
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81 | @Override |
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82 | public void stop() { |
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83 | super.stop(); |
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84 | fallBackIdGenerator.stop(); |
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85 | } |
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86 | |
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87 | /* (non-Javadoc) |
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88 | * @see de.ugoe.cs.autoquest.httpmonitor.IdGenerator#getNextId() |
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89 | */ |
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90 | @Override |
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91 | public synchronized long getNextId() { |
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92 | Request httpMonitorRequest = super.newRequest(); |
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93 | httpMonitorRequest.method(HttpMethod.GET); |
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94 | httpMonitorRequest.version(HttpVersion.HTTP_1_1); |
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95 | super.sendRequest(httpMonitorRequest); |
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96 | |
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97 | Result result = super.getResult(httpMonitorRequest); |
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98 | |
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99 | if (result.isFailed()) { |
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100 | Console.traceln |
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101 | (Level.WARNING, "could not retrieve next id correctly: " + result.getFailure()); |
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102 | Console.logException((Exception) result.getFailure()); |
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103 | |
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104 | Console.traceln(Level.WARNING, "using fallback, i.e., internal id generator"); |
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105 | return fallBackIdGenerator.getNextId(); |
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106 | } |
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107 | else { |
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108 | try { |
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109 | return result.getResponse().getHeaders().getLongField("X-AutoQUEST-OrderingId"); |
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110 | } |
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111 | catch (NumberFormatException e) { |
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112 | Console.traceln(Level.WARNING, "could not retrieve next id correctly: " + e); |
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113 | Console.logException(e); |
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114 | |
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115 | Console.traceln(Level.WARNING, "using fallback, i.e., internal id generator"); |
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116 | return fallBackIdGenerator.getNextId(); |
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117 | } |
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118 | } |
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119 | |
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120 | } |
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121 | |
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122 | } |
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