1 | /*
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2 | * OAIServer.java
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3 | * Copyright (C) 2002 New Zealand Digital Library, http://www.nzdl.org
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4 | *
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5 | * This program is free software; you can redistribute it and/or modify
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6 | * it under the terms of the GNU General Public License as published by
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7 | * the Free Software Foundation; either version 2 of the License, or
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8 | * (at your option) any later version.
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9 | *
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10 | * This program is distributed in the hope that it will be useful,
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11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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13 | * GNU General Public License for more details.
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14 | *
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15 | * You should have received a copy of the GNU General Public License
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16 | * along with this program; if not, write to the Free Software
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17 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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18 | */
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19 | package org.greenstone.gsdl3;
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20 |
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21 | import org.greenstone.gsdl3.comms.*;
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22 | import org.greenstone.gsdl3.core.*;
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23 | import org.greenstone.gsdl3.util.*;
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24 | import org.greenstone.gsdl3.action.PageAction; // used to get the default action
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25 | import org.w3c.dom.*;
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26 | import java.io.*;
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27 | import javax.servlet.*;
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28 | import javax.servlet.http.*;
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29 | import java.util.Enumeration;
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30 | import java.util.HashSet;
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31 | import java.io.File;
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32 |
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33 | import org.apache.log4j.*;
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34 |
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35 | /** a servlet to serve the OAI metadata harvesting - we are using servlets instead
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36 | * of cgi
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37 | * the init method is called only once - the first time the servlet classes
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38 | * are loaded. Each time a request comes in to the servlet, the session()
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39 | * method is called in a new thread (calls doGet/doPut etc)
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40 | * takes the verb= type args and builds a simple request to send to
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41 | * the oai receptionist, which returns a result in xml, conforming to the OAI-PMH
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42 | * protocol.
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43 | * @see Receptionist
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44 | */
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45 | /**
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46 | * OAI server configuration instructions *
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47 | *
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48 | */
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49 | public class OAIServer extends HttpServlet {
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50 |
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51 | /** the receptionist to send messages to */
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52 | protected OAIReceptionist recept=null;
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53 | /** the default language - is specified by setting a servlet param,
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54 | * otherwise DEFAULT_LANG is used*/
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55 | protected String default_lang= null;
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56 | /** The default default - used if a default lang is not specified
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57 | * in the servlet params */
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58 | protected final String DEFAULT_LANG = "en";
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59 |
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60 | /** a converter class to parse XML and create Docs
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61 | * This is only used for generating internal requests passed to MessageRouter.
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62 | * The response message is generated by parsing an existing xml skeleton file (web/WEB-INF/oaixml/oaiversion2.xml, for example).
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63 | */
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64 | protected XMLConverter converter=null;
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65 | /** container Document to create XML Nodes (but only request to the oai receptionist,
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66 | * not response (which is created in OAIXML.java) created by converter class */
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67 | protected Document doc=null;
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68 |
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69 | /** A HashSet which contains all the legal verbs. */
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70 | protected HashSet verb_set = null;
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71 | /** A HashSet which contains all the legal oai keys in the key/value argument pair. */
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72 | protected HashSet param_set = null;
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73 | /** The name of the site with which we will finally be dealing, whether it is a local site or a remote site through a communicator.*/
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74 | protected String site = "";
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75 |
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76 | static Logger logger = Logger.getLogger(org.greenstone.gsdl3.OAIServer.class.getName());
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77 |
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78 | /** initialise the servlet
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79 | */
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80 | public void init(ServletConfig config) throws ServletException {
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81 | // always call super.init, i.e., HttpServlet.;
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82 | super.init(config);
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83 | this.default_lang = config.getInitParameter(GSConstants.DEFAULT_LANG);
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84 |
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85 | initVerbs();
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86 | initParams();
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87 |
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88 | String site_name = config.getInitParameter(GSConstants.SITE_NAME);
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89 | String remote_site_name = null;
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90 | String remote_site_type = null;
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91 | String remote_site_address = null;
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92 |
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93 | if (site_name == null) {
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94 | // no local site, try for communicator (remote site)
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95 | remote_site_name = config.getInitParameter("remote_site_name");
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96 | remote_site_type = config.getInitParameter("remote_site_type");
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97 | remote_site_address = config.getInitParameter("remote_site_address");
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98 | if (remote_site_name == null || remote_site_type == null || remote_site_address == null) {
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99 | System.err.println("initialisation paramters not all set!");
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100 | System.err.println("if site_name is not set, then you must have remote_site_name, remote_site_type and remote_site_address set");
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101 | System.exit(1);
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102 | }
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103 | }
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104 |
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105 | if (this.default_lang == null) {
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106 | // choose english
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107 | this.default_lang = DEFAULT_LANG;
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108 | }
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109 |
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110 | // the receptionist -the servlet will talk to this
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111 | this.recept = new OAIReceptionist();
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112 |
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113 | // the receptionist uses a MessageRouter or Communicator to send its requests to. We either create a MessageRouter here for the designated site (if site_name set), or we create a Communicator for a remote site. The is given to teh Receptionist, and the servlet never talks to it again.directly.
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114 | if (site_name != null) {
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115 | //this site_name could consist of comma separated more than one site name.
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116 | String mr_name = (String)config.getInitParameter("messagerouter_class");
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117 | MessageRouter message_router = null;
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118 | if (mr_name == null) { // just use the normal MR *********
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119 | message_router = new MessageRouter();
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120 | } else { // try the specified one
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121 | try {
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122 | message_router = (MessageRouter)Class.forName("org.greenstone.gsdl3.core."+mr_name).newInstance();
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123 | } catch (Exception e) { // cant use this new one, so use normal one
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124 | System.err.println("OAIServlet configure exception when trying to use a new MessageRouter "+mr_name+": "+e.getMessage());
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125 | e.printStackTrace();
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126 | message_router = new MessageRouter();
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127 | }
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128 | }
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129 |
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130 | message_router.setSiteName(site_name);
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131 | // lots of work is done in this step; see MessageRouter.java
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132 | message_router.configure();
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133 | this.recept.setSiteName(site_name);
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134 | this.recept.setMessageRouter(message_router);
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135 |
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136 | } else {
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137 | // talking to a remote site, create a communicator
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138 | Communicator communicator = null;
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139 | // we need to create the XML to configure the communicator
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140 | Element site_elem = this.doc.createElement(GSXML.SITE_ELEM);
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141 | site_elem.setAttribute(GSXML.TYPE_ATT, remote_site_type);
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142 | site_elem.setAttribute(GSXML.NAME_ATT, remote_site_name);
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143 | site_elem.setAttribute(GSXML.ADDRESS_ATT, remote_site_address);
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144 |
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145 | if (remote_site_type.equals(GSXML.COMM_TYPE_SOAP_JAVA)) {
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146 | communicator = new SOAPCommunicator();
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147 | } else {
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148 | System.err.println("OAIServlet.init Error: invalid Communicator type: "+remote_site_type);
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149 | System.exit(1);
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150 | }
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151 |
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152 | if (!communicator.configure(site_elem)) {
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153 | System.err.println("OAIServlet.init Error: Couldn't configure communicator");
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154 | System.exit(1);
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155 | }
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156 | this.recept.setSiteName(remote_site_name);
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157 | this.recept.setMessageRouter(communicator);
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158 | }
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159 | // used for composing internal xml requests, but not xml responses.
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160 | // the converter may be used to get pretty xml, though.
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161 | this.converter = new XMLConverter();
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162 | this.doc = this.converter.newDOM();
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163 |
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164 | // Read in OAIConfig.xml (residing web/WEB-INF/classes/) and
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165 | //use it to configure the receptionist. The init() is also called in which
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166 | //the resumption token file is read in and all expired tokens cleared.
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167 | Element oai_config = OAIXML.getOAIConfigXML();
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168 | if (oai_config == null) {
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169 | logger.error("Fail to parse oai config file OAIConfig.xml.");
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170 | return;
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171 | }
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172 | // pass it to the receptionist
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173 | this.recept.configure(oai_config);
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174 |
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175 | }//end of init()
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176 |
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177 | private void initVerbs() {
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178 | verb_set = new HashSet();
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179 | verb_set.add(OAIXML.GET_RECORD);
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180 | verb_set.add(OAIXML.LIST_RECORDS);
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181 | verb_set.add(OAIXML.LIST_IDENTIFIERS);
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182 | verb_set.add(OAIXML.LIST_SETS);
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183 | verb_set.add(OAIXML.LIST_METADATA_FORMATS);
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184 | verb_set.add(OAIXML.IDENTIFY);
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185 | }
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186 |
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187 | private void initParams() {
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188 | param_set = new HashSet();
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189 | param_set.add(OAIXML.METADATA_PREFIX);
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190 | param_set.add(OAIXML.FROM);
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191 | param_set.add(OAIXML.UNTIL);
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192 | param_set.add(OAIXML.SET);
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193 | param_set.add(OAIXML.RESUMPTION_TOKEN);
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194 | param_set.add(OAIXML.IDENTIFIER);
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195 | }
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196 | private void logUsageInfo(HttpServletRequest request){
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197 | String usageInfo = "";
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198 |
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199 | //logged info = general-info + session-info
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200 | usageInfo =
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201 | request.getContextPath()+" "+ //session id
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202 | request.getServletPath()+" "+ //serlvet
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203 | "["+request.getQueryString()+"]" +" "+ //the query string
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204 | "["+usageInfo.trim()+"]" +" "+ // params stored in a session
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205 | request.getRemoteAddr()+" "+ //remote address
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206 | request.getHeader("user-agent")+" "; //the remote brower info
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207 |
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208 | logger.info(usageInfo);
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209 | }
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210 | /** return true if the url is in the form of baseURL?verb=...,
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211 | */
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212 | private boolean validate(String query, String verb) {
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213 | //Here in OAIServer, only the verbs are validated. All the validation for individual verb
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214 | // is taken in their doXXX() methods.
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215 | if(query == null || !query.startsWith(OAIXML.VERB+"=")) {
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216 | return false;
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217 | }
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218 | if (!verb_set.contains(verb)) {
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219 | return false;
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220 | }
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221 | return true;
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222 | }
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223 | private String getVerb(String query) {
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224 | if (query == null) return "";
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225 | int verb_start_index = query.indexOf("=") + 1;// first occurence of '='
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226 | int verb_end_index = query.indexOf("&");
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227 | if(verb_end_index == -1) {
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228 | return query.substring(verb_start_index);
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229 | }
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230 | return query.substring(verb_start_index, verb_end_index);
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231 | }
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232 | public void doGet(HttpServletRequest request, HttpServletResponse response)
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233 | throws ServletException, IOException {
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234 | PrintWriter out = response.getWriter();
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235 | logUsageInfo(request);
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236 | //out.println("url="+request.getRequestURL());// /oaiserver
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237 | //out.println("query="+request.getQueryString());// is /greenstone3
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238 |
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239 | // oai always requires the content type be text/xml
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240 | request.setCharacterEncoding("UTF-8");
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241 | response.setContentType("text/xml;charset=UTF-8");
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242 |
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243 | //
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244 | String lang = request.getParameter(GSParams.LANGUAGE);
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245 | if (lang==null || lang.equals("")) {
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246 | // use the default
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247 | lang = this.default_lang;
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248 | }
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249 | //we don't get the baseURL from the http request because what we get might be different from the one known publicly due to local network redirection.
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250 | //For example, puka.cs.waikato.ac.nz vs www.greenstone.org
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251 | //String base_url = request.getRequestURL().toString();
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252 | String query = request.getQueryString();
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253 | String[] pairs = (query==null)? null : query.split("&");//split into key/value pairs
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254 | String verb = getVerb(query);
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255 | Element xml_response = OAIXML.createBasicResponse(verb, pairs);
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256 | Element verb_elem = null;
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257 |
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258 | if (validate(query, verb) == false) {
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259 | if (verb_set.contains(verb) == false) {
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260 | logger.error(OAIXML.BAD_VERB + ": " + query);
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261 | verb_elem = OAIXML.createErrorElement(OAIXML.BAD_VERB, OAIXML.ILLEGAL_OAI_VERB);
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262 | } else {
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263 | //must be something else other than bad verbs caused an error, so bad argument
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264 | logger.error(OAIXML.BAD_ARGUMENT + ": " + query);
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265 | verb_elem = OAIXML.createErrorElement(OAIXML.BAD_ARGUMENT, "");
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266 | }
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267 | xml_response.appendChild(verb_elem);
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268 | //this line never got displayed
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269 | //out.println("<?xml version='1.0' encoding='UTF-8' ?>");
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270 | out.println(this.converter.getPrettyString(xml_response));
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271 | return;
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272 | }//end of if(validate
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273 |
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274 | // The query is valid, we can now
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275 | // compose the request message to the receptionist
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276 | Element xml_message = this.doc.createElement(GSXML.MESSAGE_ELEM);
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277 | Element xml_request = this.doc.createElement(GSXML.REQUEST_ELEM);
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278 | // The type attribute is set to be 'oaiService' from OAIServer to OAIReceptionist.
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279 | //xml_request.setAttribute(GSXML.TYPE_ATT, OAIXML.OAI_SERVICE);
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280 | xml_request.setAttribute(GSXML.LANG_ATT, lang);
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281 | xml_request.setAttribute(GSXML.TO_ATT, verb);
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282 | addParams(xml_request, pairs);
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283 |
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284 | //xml_request.setAttribute(GSXML.OUTPUT_ATT, output);????
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285 | xml_message.appendChild(xml_request);
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286 |
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287 | Node xml_result = this.recept.process (xml_message);
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288 | if (xml_result == null) {
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289 | logger.info("xml_result is null");
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290 | verb_elem = OAIXML.createErrorElement("Internal error", "");
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291 | xml_response.appendChild(verb_elem);
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292 | } else {
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293 |
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294 | /** All response elements are in the form (with a corresponding verb name):
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295 | * <message>
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296 | <response>
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297 | <verb>
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298 | ...
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299 | * <resumptionToken>
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300 | * .. this is optional!
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301 | * </resumptionToken>
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302 | * </verb>
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303 | * </response>
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304 | * </message>
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305 | */
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306 | Node res = GSXML.getChildByTagName(xml_result, OAIXML.RESPONSE);
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307 | if(res == null) {
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308 | logger.info("response element in xml_result is null");
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309 | verb_elem = OAIXML.createErrorElement("Internal error", "");
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310 | } else {
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311 | verb_elem = GSXML.getFirstElementChild(res);
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312 | }
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313 |
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314 | if(OAIXML.oai_version.equals(OAIXML.OAI_VERSION2) ||
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315 | verb_elem.getTagName().equals(OAIXML.ERROR)) {
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316 | xml_response.appendChild(xml_response.getOwnerDocument().importNode(verb_elem, true));
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317 | } else {
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318 | GSXML.copyAllChildren(xml_response, verb_elem);
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319 | }
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320 | }
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321 | out.println (this.converter.getPrettyString (xml_response));
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322 | return;
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323 | }
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324 | /** append parameter elements to the request sent to the receptionist*/
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325 | public void addParams(Element request, String[] pairs) {
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326 | // no params apart from the verb
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327 | if (pairs == null || pairs.length < 2) return ;
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328 |
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329 | /**the request xml is composed in the form: <request>
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330 | * <param name=.../>
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331 | * <param name=.../>
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332 | * </request>
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333 | *(No paramList element in between).
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334 | */
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335 | for (int i=1; i<pairs.length; i++) {
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336 | //the first pair in pairs is the verb=xxx
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337 | int index = pairs[i].indexOf("=");
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338 | if(index != -1){ //just a double check
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339 | Element param = this.doc.createElement(OAIXML.PARAM);
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340 | param.setAttribute(OAIXML.NAME, pairs[i].substring(0, index));
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341 | param.setAttribute(OAIXML.VALUE, OAIXML.oaiDecode(pairs[i].substring(index + 1)));
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342 | request.appendChild(param);
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343 | }
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344 | }
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345 | }
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346 | public void doPost(HttpServletRequest request,
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347 | HttpServletResponse response)
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348 | throws ServletException, IOException {
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349 | doGet(request,response);
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350 | }
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351 | }
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352 |
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353 |
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354 |
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355 |
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356 |
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357 |
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358 |
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359 |
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360 |
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361 |
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362 |
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363 |
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364 |
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365 |
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366 |
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