1 | package eu.clarin.sru.server.fcs; |
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2 | |
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3 | import java.net.URI; |
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4 | import java.util.List; |
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5 | import java.util.Map; |
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6 | |
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7 | import javax.servlet.ServletContext; |
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8 | import javax.xml.XMLConstants; |
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9 | import javax.xml.stream.XMLStreamException; |
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10 | import javax.xml.stream.XMLStreamWriter; |
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11 | |
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12 | import org.slf4j.Logger; |
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13 | import org.slf4j.LoggerFactory; |
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14 | import org.z3950.zing.cql.CQLNode; |
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15 | import org.z3950.zing.cql.CQLTermNode; |
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16 | import eu.clarin.sru.server.SRUConfigException; |
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17 | import eu.clarin.sru.server.SRUConstants; |
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18 | import eu.clarin.sru.server.SRUDiagnosticList; |
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19 | import eu.clarin.sru.server.SRUException; |
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20 | import eu.clarin.sru.server.SRUExplainResult; |
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21 | import eu.clarin.sru.server.SRUQueryParserRegistry; |
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22 | import eu.clarin.sru.server.SRURequest; |
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23 | import eu.clarin.sru.server.SRUScanResultSet; |
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24 | import eu.clarin.sru.server.SRUSearchEngine; |
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25 | import eu.clarin.sru.server.SRUServerConfig; |
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26 | import eu.clarin.sru.server.utils.SRUSearchEngineBase; |
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27 | |
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28 | |
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29 | /** |
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30 | * A base class for implementing a simple search engine to be used as a |
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31 | * CLARIN-FCS endpoint. |
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32 | * |
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33 | */ |
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34 | public abstract class SimpleEndpointSearchEngineBase extends |
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35 | SRUSearchEngineBase { |
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36 | private static final String X_FCS_ENDPOINT_DESCRIPTION = |
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37 | "x-fcs-endpoint-description"; |
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38 | private static final String ED_NS = |
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39 | "http://clarin.eu/fcs/endpoint-description"; |
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40 | private static final String ED_PREFIX = "ed"; |
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41 | private static final int ED_VERSION = 2; |
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42 | private static final Logger logger = |
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43 | LoggerFactory.getLogger(SimpleEndpointSearchEngineBase.class); |
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44 | protected EndpointDescription endpointDescription; |
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45 | |
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46 | |
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47 | /** |
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48 | * This method should not be overridden. Perform your custom initialization |
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49 | * in the {@link #doInit(ServletContext, SRUServerConfig, Map)} method |
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50 | * Instead. |
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51 | * |
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52 | * @see #doInit(ServletContext, SRUServerConfig, Map) |
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53 | */ |
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54 | @Override |
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55 | public final void init(ServletContext context, |
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56 | SRUServerConfig config, |
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57 | SRUQueryParserRegistry queryParsers, |
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58 | Map<String, String> params) throws SRUConfigException { |
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59 | logger.debug("initializing"); |
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60 | super.init(context, config, queryParsers, params); |
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61 | |
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62 | queryParsers.registerQueryParser(new FCSQueryParser()); |
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63 | |
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64 | logger.debug("initializing search engine implementation"); |
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65 | doInit(context, config, queryParsers, params); |
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66 | |
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67 | logger.debug("initizalizing endpoint description"); |
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68 | this.endpointDescription = |
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69 | createEndpointDescription(context, config, params); |
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70 | if (this.endpointDescription == null) { |
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71 | logger.error("SimpleEndpointSearchEngineBase implementation " + |
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72 | "error: createEndpointDescription() returned null"); |
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73 | throw new SRUConfigException("createEndpointDescription() " + |
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74 | "returned no valid implementation of an EndpointDescription"); |
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75 | } |
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76 | } |
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77 | |
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78 | |
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79 | /** |
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80 | * This method should not be overridden. Perform you custom cleanup in the |
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81 | * {@link #doDestroy()} method. |
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82 | * |
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83 | * @see #doDestroy() |
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84 | */ |
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85 | @Override |
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86 | public final void destroy() { |
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87 | logger.debug("performing cleanup of endpoint description"); |
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88 | endpointDescription.destroy(); |
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89 | logger.debug("performing cleanup of search engine"); |
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90 | doDestroy(); |
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91 | super.destroy(); |
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92 | } |
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93 | |
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94 | |
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95 | @Override |
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96 | public final SRUExplainResult explain(SRUServerConfig config, |
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97 | SRURequest request, SRUDiagnosticList diagnostics) |
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98 | throws SRUException { |
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99 | |
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100 | final boolean provideEndpointDescription = |
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101 | parseBoolean(request.getExtraRequestData( |
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102 | X_FCS_ENDPOINT_DESCRIPTION)); |
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103 | |
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104 | if (provideEndpointDescription) { |
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105 | return new SRUExplainResult(diagnostics) { |
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106 | @Override |
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107 | public boolean hasExtraResponseData() { |
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108 | return provideEndpointDescription; |
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109 | } |
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110 | |
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111 | |
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112 | @Override |
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113 | public void writeExtraResponseData(XMLStreamWriter writer) |
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114 | throws XMLStreamException { |
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115 | writeEndpointDescription(writer); |
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116 | } |
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117 | }; |
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118 | } else { |
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119 | return null; |
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120 | } |
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121 | } |
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122 | |
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123 | |
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124 | /** |
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125 | * Handle a <em>scan</em> operation. This implementation provides support to |
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126 | * CLARIN FCS resource enumeration. If you want to provide custom scan |
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127 | * behavior for a different index, override the |
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128 | * {@link #doScan(SRUServerConfig, SRURequest, SRUDiagnosticList)} method. |
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129 | * |
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130 | * @see #doScan(SRUServerConfig, SRURequest, SRUDiagnosticList) |
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131 | */ |
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132 | @Override |
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133 | public final SRUScanResultSet scan(SRUServerConfig config, |
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134 | SRURequest request, SRUDiagnosticList diagnostics) |
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135 | throws SRUException { |
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136 | return doScan(config, request, diagnostics); |
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137 | } |
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138 | |
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139 | |
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140 | protected abstract EndpointDescription createEndpointDescription( |
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141 | ServletContext context, SRUServerConfig config, |
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142 | Map<String, String> params) throws SRUConfigException; |
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143 | |
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144 | |
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145 | /** |
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146 | * Initialize the search engine. This initialization should be tailed |
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147 | * towards your environment and needs. |
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148 | * |
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149 | * @param context |
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150 | * the {@link ServletContext} for the Servlet |
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151 | * @param config |
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152 | * the {@link SRUServerConfig} object for this search engine |
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153 | * @param queryParsers |
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154 | * the {@link SRUQueryParserRegistry} object for this search |
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155 | * engine |
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156 | * @param params |
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157 | * additional parameters gathered from the Servlet configuration |
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158 | * and Servlet context. |
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159 | * @throws SRUConfigException |
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160 | * if an error occurred |
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161 | */ |
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162 | protected abstract void doInit(ServletContext context, |
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163 | SRUServerConfig config, |
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164 | SRUQueryParserRegistry queryParsers, |
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165 | Map<String, String> params) throws SRUConfigException; |
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166 | |
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167 | |
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168 | /** |
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169 | * Destroy the search engine. Override this method for any cleanup the |
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170 | * search engine needs to perform upon termination. |
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171 | */ |
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172 | protected void doDestroy() { |
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173 | } |
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174 | |
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175 | |
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176 | /** |
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177 | * Handle a <em>scan</em> operation. The default implementation is a no-op. |
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178 | * Override this method, if you want to provide a custom behavior. |
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179 | * |
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180 | * @param config |
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181 | * the <code>SRUEndpointConfig</code> object that contains the |
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182 | * endpoint configuration |
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183 | * @param request |
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184 | * the <code>SRURequest</code> object that contains the request |
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185 | * made to the endpoint |
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186 | * @param diagnostics |
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187 | * the <code>SRUDiagnosticList</code> object for storing |
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188 | * non-fatal diagnostics |
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189 | * @return a <code>SRUScanResultSet</code> object or <code>null</code> if |
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190 | * this operation is not supported by this search engine |
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191 | * @throws SRUException |
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192 | * if an fatal error occurred |
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193 | * @see SRUSearchEngine#scan(SRUServerConfig, SRURequest, SRUDiagnosticList) |
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194 | * @deprecated override |
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195 | * {@link #scan(SRUServerConfig, SRURequest, SRUDiagnosticList)} |
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196 | */ |
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197 | @Deprecated |
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198 | protected SRUScanResultSet doScan(SRUServerConfig config, |
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199 | SRURequest request, SRUDiagnosticList diagnostics) |
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200 | throws SRUException { |
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201 | final CQLNode scanClause = request.getScanClause(); |
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202 | if (scanClause instanceof CQLTermNode) { |
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203 | final CQLTermNode root = (CQLTermNode) scanClause; |
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204 | final String index = root.getIndex(); |
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205 | throw new SRUException(SRUConstants.SRU_UNSUPPORTED_INDEX, index, |
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206 | "scan operation on index '" + index + "' is not supported"); |
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207 | } else { |
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208 | throw new SRUException(SRUConstants.SRU_QUERY_FEATURE_UNSUPPORTED, |
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209 | "Scan clause too complex."); |
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210 | } |
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211 | } |
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212 | |
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213 | |
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214 | /** |
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215 | * Convince method for parsing a string to boolean. Values <code>1</code>, |
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216 | * <code>true</code>, <code>yes</code> yield a <em>true</em> boolean value |
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217 | * as a result, all others (including <code>null</code>) a <em>false</em> |
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218 | * boolean value. |
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219 | * |
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220 | * @param value |
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221 | * the string to parse |
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222 | * @return <code>true</code> if the supplied string was considered something |
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223 | * representing a <em>true</em> boolean value, <code>false</code> |
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224 | * otherwise |
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225 | */ |
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226 | protected static boolean parseBoolean(String value) { |
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227 | if (value != null) { |
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228 | return value.equals("1") || Boolean.parseBoolean(value); |
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229 | } |
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230 | return false; |
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231 | } |
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232 | |
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233 | |
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234 | private void writeEndpointDescription(XMLStreamWriter writer) |
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235 | throws XMLStreamException { |
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236 | writer.setPrefix(ED_PREFIX, ED_NS); |
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237 | writer.writeStartElement(ED_NS, "EndpointDescription"); |
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238 | writer.writeNamespace(ED_PREFIX, ED_NS); |
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239 | writer.writeAttribute("version", Integer.toString(ED_VERSION)); |
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240 | |
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241 | // Capabilities |
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242 | writer.writeStartElement(ED_NS, "Capabilities"); |
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243 | for (URI capability : endpointDescription.getCapabilities()) { |
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244 | writer.writeStartElement(ED_NS, "Capability"); |
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245 | writer.writeCharacters(capability.toString()); |
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246 | writer.writeEndElement(); // "Capability" element |
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247 | } |
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248 | writer.writeEndElement(); // "Capabilities" element |
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249 | |
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250 | // SupportedDataViews |
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251 | writer.writeStartElement(ED_NS, "SupportedDataViews"); |
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252 | for (DataView dataView : endpointDescription.getSupportedDataViews()) { |
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253 | writer.writeStartElement(ED_NS, "SupportedDataView"); |
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254 | writer.writeAttribute("id", dataView.getIdentifier()); |
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255 | String s; |
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256 | switch (dataView.getDeliveryPolicy()) { |
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257 | case SEND_BY_DEFAULT: |
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258 | s = "send-by-default"; |
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259 | break; |
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260 | case NEED_TO_REQUEST: |
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261 | s = "need-to-request"; |
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262 | break; |
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263 | default: |
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264 | throw new XMLStreamException( |
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265 | "invalid value for payload delivery policy: " + |
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266 | dataView.getDeliveryPolicy()); |
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267 | } // switch |
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268 | writer.writeAttribute("delivery-policy", s); |
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269 | writer.writeCharacters(dataView.getMimeType()); |
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270 | writer.writeEndElement(); // "SupportedDataView" element |
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271 | } |
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272 | writer.writeEndElement(); // "SupportedDataViews" element |
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273 | |
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274 | // SupportedLayers |
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275 | final List<Layer> layers = endpointDescription.getSupportedLayers(); |
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276 | if (layers != null) { |
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277 | writer.writeStartElement(ED_NS, "SupportedLayers"); |
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278 | for (Layer layer : layers) { |
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279 | writer.writeStartElement(ED_NS, "SupportedLayer"); |
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280 | writer.writeAttribute("id", layer.getId()); |
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281 | writer.writeAttribute("result-id", |
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282 | layer.getResultId().toString()); |
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283 | if (layer.getContentEncoding() == Layer.ContentEncoding.EMPTY) { |
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284 | writer.writeAttribute("type", "empty"); |
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285 | } |
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286 | if (layer.getQualifier() != null) { |
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287 | writer.writeAttribute("qualifier", layer.getQualifier()); |
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288 | } |
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289 | if (layer.getAltValueInfo() != null) { |
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290 | writer.writeAttribute("alt-value-info", |
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291 | layer.getAltValueInfo()); |
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292 | if (layer.getAltValueInfoURI() != null) { |
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293 | writer.writeAttribute("alt-value-info-uri", |
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294 | layer.getAltValueInfoURI().toString()); |
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295 | } |
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296 | } |
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297 | writer.writeCharacters(layer.getType()); |
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298 | writer.writeEndElement(); // "SupportedLayer" element |
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299 | } |
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300 | writer.writeEndElement(); // "SupportedLayers" element |
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301 | |
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302 | } |
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303 | |
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304 | // Resources |
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305 | try { |
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306 | List<ResourceInfo> resources = |
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307 | endpointDescription.getResourceList( |
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308 | EndpointDescription.PID_ROOT); |
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309 | writeResourceInfos(writer, resources); |
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310 | } catch (SRUException e) { |
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311 | throw new XMLStreamException("error retriving top-level resources", |
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312 | e); |
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313 | } |
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314 | writer.writeEndElement(); // "EndpointDescription" element |
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315 | } |
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316 | |
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317 | |
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318 | private void writeResourceInfos(XMLStreamWriter writer, |
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319 | List<ResourceInfo> resources) throws XMLStreamException { |
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320 | if (resources == null) { |
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321 | throw new NullPointerException("resources == null"); |
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322 | } |
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323 | if (!resources.isEmpty()) { |
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324 | writer.writeStartElement(ED_NS, "Resources"); |
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325 | |
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326 | for (ResourceInfo resource : resources) { |
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327 | writer.writeStartElement(ED_NS, "Resource"); |
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328 | writer.writeAttribute("pid", resource.getPid()); |
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329 | |
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330 | // title |
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331 | final Map<String, String> title = resource.getTitle(); |
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332 | for (Map.Entry<String, String> i : title.entrySet()) { |
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333 | writer.setPrefix(XMLConstants.XML_NS_PREFIX, |
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334 | XMLConstants.XML_NS_URI); |
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335 | writer.writeStartElement(ED_NS, "Title"); |
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336 | writer.writeAttribute(XMLConstants.XML_NS_URI, "lang", i.getKey()); |
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337 | writer.writeCharacters(i.getValue()); |
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338 | writer.writeEndElement(); // "title" element |
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339 | } |
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340 | |
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341 | // description |
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342 | final Map<String, String> description = resource.getDescription(); |
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343 | if (description != null) { |
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344 | for (Map.Entry<String, String> i : description.entrySet()) { |
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345 | writer.writeStartElement(ED_NS, "Description"); |
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346 | writer.writeAttribute(XMLConstants.XML_NS_URI, "lang", |
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347 | i.getKey()); |
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348 | writer.writeCharacters(i.getValue()); |
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349 | writer.writeEndElement(); // "Description" element |
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350 | } |
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351 | } |
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352 | |
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353 | // landing page |
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354 | final String landingPageURI = resource.getLandingPageURI(); |
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355 | if (landingPageURI != null) { |
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356 | writer.writeStartElement(ED_NS, "LandingPageURI"); |
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357 | writer.writeCharacters(landingPageURI); |
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358 | writer.writeEndElement(); // "LandingPageURI" element |
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359 | } |
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360 | |
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361 | // languages |
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362 | final List<String> languages = resource.getLanguages(); |
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363 | writer.writeStartElement(ED_NS, "Languages"); |
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364 | for (String i : languages) { |
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365 | writer.writeStartElement(ED_NS, "Language"); |
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366 | writer.writeCharacters(i); |
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367 | writer.writeEndElement(); // "Language" element |
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368 | |
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369 | } |
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370 | writer.writeEndElement(); // "Languages" element |
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371 | |
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372 | // available data views |
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373 | StringBuilder sb = new StringBuilder(); |
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374 | for (DataView dataview : resource.getAvailableDataViews()) { |
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375 | if (sb.length() > 0) { |
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376 | sb.append(" "); |
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377 | } |
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378 | sb.append(dataview.getIdentifier()); |
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379 | } |
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380 | writer.writeEmptyElement(ED_NS, "AvailableDataViews"); |
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381 | writer.writeAttribute("ref", sb.toString()); |
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382 | |
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383 | final List<Layer> layers = resource.getAvailableLayers(); |
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384 | if (layers != null) { |
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385 | sb = new StringBuilder(); |
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386 | for (Layer layer : resource.getAvailableLayers()) { |
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387 | if (sb.length() > 0) { |
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388 | sb.append(" "); |
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389 | } |
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390 | sb.append(layer.getId()); |
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391 | } |
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392 | writer.writeEmptyElement(ED_NS, "AvailableLayers"); |
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393 | writer.writeAttribute("ref", sb.toString()); |
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394 | } |
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395 | |
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396 | // child resources |
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397 | List<ResourceInfo> subs = resource.getSubResources(); |
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398 | if ((subs != null) && !subs.isEmpty()) { |
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399 | writeResourceInfos(writer, subs); |
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400 | } |
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401 | |
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402 | writer.writeEndElement(); // "Resource" element |
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403 | } |
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404 | writer.writeEndElement(); // "Resources" element |
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405 | } |
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406 | } |
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407 | |
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408 | } // class SimpleEndpointSearchEngineBase |
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