1 | /*
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2 | * ServiceRack.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.service;
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20 |
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21 | // greenstone classes
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22 | import org.greenstone.gsdl3.util.*;
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23 | import org.greenstone.gsdl3.core.*;
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24 |
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25 | // xml classes
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26 | import org.w3c.dom.Node;
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27 | import org.w3c.dom.NodeList;
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28 | import org.w3c.dom.Element;
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29 | import org.w3c.dom.Document;
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30 | import org.xml.sax.InputSource;
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31 | import javax.xml.parsers.*;
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32 | import org.apache.xpath.XPathAPI;
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33 |
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34 | // general java classes
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35 | import java.io.Reader;
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36 | import java.io.StringReader;
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37 | import java.io.File;
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38 | import java.util.HashMap;
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39 | import java.util.ResourceBundle;
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40 | import java.util.Locale;
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41 | import java.lang.reflect.Method;
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42 |
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43 | /**
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44 | * ServiceRack - abstract base class for services
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45 | *
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46 | * A ServiceRack provides one or more Services.
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47 | * This base class implements the process method.
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48 | *Each service is invoked
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49 | * by a method called process<service name> which takes one parameter - the xml request Element, and returns an XML response Element.
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50 | * for example, the TextQuery service would be invoked by
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51 | * processTextQuery(Element request)
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52 | *
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53 | * @author <a href="mailto:[email protected]">Katherine Don</a>
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54 | * @version $Revision: 4903 $
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55 | */
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56 | public abstract class ServiceRack
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57 | implements ModuleInterface
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58 | {
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59 |
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60 | /** the absolute address of the site home */
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61 | protected String site_home_ =null;
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62 | /** the http address of the site home */
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63 | protected String site_http_address_ =null;
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64 |
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65 | /** the name of the cluster (or collection) that this service
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66 | belongs to - if any */
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67 | protected String cluster_name_ = null;
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68 |
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69 | /** some services can talk back to the message router */
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70 | protected ModuleInterface router_ = null;
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71 |
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72 | /** a converter class to create Documents etc */
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73 | protected XMLConverter converter_ = null;
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74 |
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75 | /** the original config info - if need to store it */
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76 | protected Element config_info_ = null;
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77 |
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78 | /** XML element for describe requests - the container doc */
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79 | protected Document doc_ = null;
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80 |
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81 | /** XML element for describe requests - list of supported services
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82 | - this is static */
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83 | protected Element short_service_info_ = null;
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84 |
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85 | /** XML element for stylesheet requests - map of service name to format
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86 | elem */
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87 | protected HashMap format_info_map_ = null;
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88 |
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89 | /** sets the cluster name */
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90 | public void setClusterName(String cluster_name) {
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91 | cluster_name_ = cluster_name;
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92 | }
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93 | /** sets the collect name */
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94 | public void setCollectionName(String coll_name) {
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95 | setClusterName(coll_name);
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96 | }
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97 |
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98 | /** sets the site home */
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99 | public void setSiteHome(String site_home) {
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100 | site_home_ = site_home;
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101 | }
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102 | /** sets the site http address */
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103 | public void setSiteAddress(String site_address) {
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104 | site_http_address_ = site_address;
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105 | }
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106 |
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107 | /** sets the message router */
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108 | public void setMessageRouter(ModuleInterface m) {
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109 | router_ = m;
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110 | }
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111 |
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112 | /** the no-args constructor */
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113 | public ServiceRack() {
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114 | converter_ = new XMLConverter();
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115 | doc_ = converter_.newDOM();
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116 | short_service_info_ = doc_.createElement(GSXML.SERVICE_ELEM+GSXML.LIST_MODIFIER);
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117 | format_info_map_ = new HashMap();
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118 | }
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119 |
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120 |
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121 | /** configure the service module
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122 | *
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123 | * @param info the XML node <serviceRack name="XXX"/> with name equal
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124 | * to the class name (of the subclass)
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125 | *
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126 | * must configure short_service_info_ and service_info_map_
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127 | * @return true if configured ok
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128 | * must be implemented in subclasses
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129 | */
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130 | public boolean configure(Element info) {
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131 | return configure(info, null);
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132 | }
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133 |
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134 | abstract public boolean configure(Element info, Element extra_info);
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135 |
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136 | /**
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137 | * Process an XML document - convenience method that uses Strings rather than Elements. just calls process(Element).
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138 | *
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139 | * @param xml_in the Document to process - a string
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140 | * @return the resultant document as a string - contains any error messages
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141 | * @see String
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142 | */
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143 | public String process(String xml_in) {
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144 |
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145 | Document doc = converter_.getDOM(xml_in);
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146 |
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147 | Element res = process(doc.getDocumentElement());
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148 | return converter_.getString(res);
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149 |
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150 | }
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151 |
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152 | /** process an XML request in DOM form
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153 | *
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154 | * @param xml_in the Element node containing the request
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155 | * should be <message>
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156 | * @return an Element with the result XML
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157 | * @see Element
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158 | */
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159 | public Element process(Element message) {
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160 |
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161 | NodeList requests = message.getElementsByTagName(GSXML.REQUEST_ELEM);
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162 | Document mess_doc = message.getOwnerDocument();
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163 | Element mainResult = doc_.createElement(GSXML.MESSAGE_ELEM);
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164 | if (requests.getLength()==0) {
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165 | // no requests
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166 | return mainResult; // empty message for now
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167 | }
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168 |
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169 | for (int i=0; i<requests.getLength(); i++) {
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170 | Element request = (Element)requests.item(i);
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171 |
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172 | String type = request.getAttribute(GSXML.TYPE_ATT);
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173 | if (type.equals(GSXML.REQUEST_TYPE_DESCRIBE)) {
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174 | Element response = processDescribe(request);
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175 | if (response !=null) {
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176 | mainResult.appendChild(doc_.importNode(response, true));
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177 | }
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178 |
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179 | } else if (type.equals(GSXML.REQUEST_TYPE_FORMAT)) {
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180 | Element response = processFormat(request);
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181 | mainResult.appendChild(doc_.importNode(response, true));
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182 |
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183 |
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184 | } else {
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185 | // other type of request, must be processed by the subclass -
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186 | // send to the service method
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187 |
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188 | String to = GSPath.getFirstLink(request.getAttribute(GSXML.TO_ATT));
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189 | Element response = null;
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190 | try {
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191 | Class c = this.getClass();
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192 | Class []params = {Class.forName("org.w3c.dom.Element")};
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193 |
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194 | String method_name = "process"+to;
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195 | Method m = null;
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196 | while (c != null) {
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197 |
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198 | try {
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199 | m = c.getDeclaredMethod(method_name, params);
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200 | // if this has worked, break
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201 | break;
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202 | } catch (NoSuchMethodException e) {
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203 | c = c.getSuperclass();
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204 | } catch (SecurityException e) {
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205 | System.err.println("ServiceRack.process: security exception for finding method "+method_name+", returning null");
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206 | return null;
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207 | }
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208 | } // while
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209 | if (m != null) {
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210 | Object []args = {request};
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211 | try {
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212 | response = (Element)m.invoke(this, args);
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213 |
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214 | } catch (Exception e) {
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215 | System.err.println("ServiceRack.process: Trying to call a processService type method (process"+to+") on a subclass("+this.getClass().getName()+"), but an exception happened:"+e.toString());
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216 | return null;
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217 | }
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218 | } else {
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219 | System.err.println("ServiceRack.process: method "+method_name+" not found for class "+this.getClass().getName());
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220 | }
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221 | if (response !=null) {
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222 | mainResult.appendChild(doc_.importNode(response, true));
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223 | }
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224 |
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225 | } catch (ClassNotFoundException e) {
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226 | System.err.println("ServiceRack error: Element class not found");
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227 | return null;
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228 | }
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229 | }
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230 | } // for each request
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231 |
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232 | return mainResult;
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233 |
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234 | }
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235 |
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236 |
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237 |
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238 | /** process method for describe requests
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239 | */
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240 | protected Element processDescribe(Element request) {
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241 |
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242 | Element response = doc_.createElement(GSXML.RESPONSE_ELEM);
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243 | response.setAttribute(GSXML.TYPE_ATT, GSXML.REQUEST_TYPE_DESCRIBE);
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244 |
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245 | String lang = request.getAttribute(GSXML.LANG_ATT);
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246 | String to = GSPath.getFirstLink(request.getAttribute(GSXML.TO_ATT));
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247 | if (to.equals("")) { // return the service list
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248 | response.appendChild(getServiceList(lang));
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249 | return response;
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250 | }
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251 |
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252 | // describe a particular service
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253 | //if (service_info_map_.containsKey(to)) {
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254 | Element description = getServiceDescription(to, lang);
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255 | if (description != null) { // may be null if non-existant service
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256 | response.appendChild(description);
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257 | response.setAttribute(GSXML.FROM_ATT, to);
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258 | }
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259 | return response;
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260 |
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261 | }
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262 |
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263 | /** process method for stylesheet requests
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264 | */
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265 | protected Element processFormat(Element request) {
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266 | Element response = doc_.createElement(GSXML.RESPONSE_ELEM);
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267 | response.setAttribute(GSXML.TYPE_ATT, GSXML.REQUEST_TYPE_FORMAT);
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268 |
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269 | String to = GSPath.getFirstLink(request.getAttribute(GSXML.TO_ATT));
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270 |
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271 | if (to.equals("")) { // serviceRack query - is this appropriate??
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272 | return response;
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273 | }
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274 |
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275 |
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276 | // describe a particular service
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277 | if (format_info_map_.containsKey(to)) {
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278 | response.appendChild(getServiceFormat(to));
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279 | response.setAttribute(GSXML.FROM_ATT, to);
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280 | return response;
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281 | }
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282 | // else no format info
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283 | System.err.println("ServiceRack describe request: no format info for "+to+".");
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284 | return response;
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285 | }
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286 |
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287 | /** returns the service list for the subclass */
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288 | protected Element getServiceList(String lang) {
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289 | // for now, it is static and has no language stuff
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290 | return (Element) short_service_info_.cloneNode(true);
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291 | }
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292 |
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293 | /** returns a specific service description */
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294 | abstract protected Element getServiceDescription(String service, String lang);
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295 |
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296 | protected Element getServiceFormat(String service) {
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297 | Element format = (Element)((Element)format_info_map_.get(service)).cloneNode(true);
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298 | return format;
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299 | }
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300 |
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301 | /** overloaded version for no args case */
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302 | protected String getTextString(String key, String lang) {
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303 | return getTextString(key, null, lang);
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304 | }
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305 | /** getTextString - retrieves a language specific text string for the given
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306 | key and locale
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307 | */
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308 | protected String getTextString(String key, String[] args, String lang) {
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309 |
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310 | String class_name = this.getClass().getName();
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311 | class_name = class_name.substring(class_name.lastIndexOf('.')+1);
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312 |
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313 | Dictionary dict = new Dictionary(class_name, lang);
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314 | String result = dict.get(key, args);
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315 | if (result == null) { // not found
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316 | return "_"+key+"_";
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317 | }
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318 | return result;
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319 | }
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320 |
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321 |
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322 | }
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323 |
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