source: trunk/gsdl3/src/java/org/greenstone/gsdl3/service/ServiceRack.java@ 3990

Last change on this file since 3990 was 3946, checked in by kjdon, 21 years ago

tidied up System.out.prints
  • Property svn:keywords set to Author Date Id Revision
File size: 11.4 KB
Line 
1/*
2 * ServiceRack.java
3 * Copyright (C) 2002 New Zealand Digital Library, http://www.nzdl.org
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
18 */
19package org.greenstone.gsdl3.service;
20
21// greenstone classes
22import org.greenstone.gsdl3.util.*;
23import org.greenstone.gsdl3.core.*;
24
25// xml classes
26import org.w3c.dom.Node;
27import org.w3c.dom.NodeList;
28import org.w3c.dom.Element;
29import org.w3c.dom.Document;
30import org.xml.sax.InputSource;
31import javax.xml.parsers.*;
32import org.apache.xpath.XPathAPI;
33
34// general java classes
35import java.io.Reader;
36import java.io.StringReader;
37import java.io.File;
38import java.util.HashMap;
39import java.util.ResourceBundle;
40import java.util.Locale;
41import java.lang.reflect.Method;
42
43/**
44 * ServiceRack - abstract base class for services
45 *
46 * A ServiceRack provides one or more Services.
47 * This base class implements the process method.
48 *Each service is invoked
49 * by a method called process<service name> which takes one parameter - the xml request Element, and returns an XML response Element.
50 * for example, the TextQuery service would be invoked by
51 * processTextQuery(Element request)
52 *
53 * @author <a href="mailto:[email protected]">Katherine Don</a>
54 * @version $Revision: 3946 $
55 */
56public abstract class ServiceRack
57 implements ModuleInterface
58{
59
60 /** the absolute address of the site home */
61 protected String site_home_ =null;
62 /** the name of the cluster (or collection) that this service
63 belongs to - if any */
64 protected String cluster_name_ = null;
65
66 /** some services can talk back to the message router */
67 protected ModuleInterface router_ = null;
68
69 /** a converter class to create Documents etc */
70 protected XMLConverter converter_ = null;
71
72 /** the original config info - if need to store it */
73 protected Element config_info_ = null;
74
75 /** XML element for describe requests - the container doc */
76 protected Document doc_ = null;
77
78 /** XML element for describe requests - list of supported services */
79 protected Element short_service_info_ = null;
80
81 /** XML element for describe requests - map of service name to full
82 description */
83 protected HashMap service_info_map_ = null;
84 /** XML element for stylesheet requests - map of service name to format
85 elem */
86 protected HashMap format_info_map_ = null;
87
88 /** sets the cluster name */
89 public void setClusterName(String cluster_name) {
90 cluster_name_ = cluster_name;
91 }
92 /** sets the collect name */
93 public void setCollectionName(String coll_name) {
94 setClusterName(coll_name);
95 }
96
97 /** sets the site home */
98 public void setSiteHome(String site_home) {
99 site_home_ = site_home;
100 }
101
102 /** sets the message router */
103 public void setMessageRouter(ModuleInterface m) {
104 router_ = m;
105 }
106
107 /** the no-args constructor */
108 public ServiceRack() {
109 converter_ = new XMLConverter();
110 doc_ = converter_.newDOM();
111 short_service_info_ = doc_.createElement(GSXML.SERVICE_ELEM+GSXML.LIST_MODIFIER);
112 service_info_map_ = new HashMap();
113 format_info_map_ = new HashMap();
114 }
115
116
117 /** configure the service module
118 *
119 * @param info the XML node <serviceRack name="XXX"/> with name equal
120 * to the class name (of the subclass)
121 *
122 * must configure short_service_info_ and service_info_map_
123 * @return true if configured ok
124 * must be implemented in subclasses
125 */
126 public boolean configure(Element info) {
127 return configure(info, null);
128 }
129
130 abstract public boolean configure(Element info, Element extra_info);
131
132 /**
133 * Process an XML document - convenience method that uses Strings rather than Elements. just calls process(Element).
134 *
135 * @param xml_in the Document to process - a string
136 * @return the resultant document as a string - contains any error messages
137 * @see String
138 */
139 public String process(String xml_in) {
140
141 Document doc = converter_.getDOM(xml_in);
142
143 Element res = process(doc.getDocumentElement());
144 return converter_.getString(res);
145
146 }
147
148 /** process an XML request in DOM form
149 *
150 * @param xml_in the Element node containing the request
151 * should be <message>
152 * @return an Element with the result XML
153 * @see Element
154 */
155 public Element process(Element message) {
156
157 NodeList requests = message.getElementsByTagName(GSXML.REQUEST_ELEM);
158 Document mess_doc = message.getOwnerDocument();
159 Element mainResult = doc_.createElement(GSXML.MESSAGE_ELEM);
160 if (requests.getLength()==0) {
161 // no requests
162 return mainResult; // empty message for now
163 }
164
165 for (int i=0; i<requests.getLength(); i++) {
166 Element request = (Element)requests.item(i);
167
168 String type = request.getAttribute(GSXML.TYPE_ATT);
169 if (type.equals(GSXML.REQUEST_TYPE_DESCRIBE)) {
170 Element response = processDescribe(request);
171 if (response !=null) {
172 mainResult.appendChild(doc_.importNode(response, true));
173 }
174
175 } else if (type.equals(GSXML.REQUEST_TYPE_FORMAT)) {
176 Element response = processFormat(request);
177 mainResult.appendChild(doc_.importNode(response, true));
178
179
180 } else {
181 // other type of request, must be processed by the subclass -
182 // send to the service method
183
184 String to = GSPath.getFirstLink(request.getAttribute(GSXML.TO_ATT));
185 Element response = null;
186 if (service_info_map_.containsKey(to)) {
187 try {
188 Class c = this.getClass();
189 Class []params = {Class.forName("org.w3c.dom.Element")};
190
191 String method_name = "process"+to;
192 Method m = null;
193 while (c != null) {
194
195 try {
196 m = c.getDeclaredMethod(method_name, params);
197 // if this has worked, break
198 break;
199 } catch (NoSuchMethodException e) {
200 c = c.getSuperclass();
201 } catch (SecurityException e) {
202 System.err.println("ServiceRack.process: security exception for finding method "+method_name+", returning null");
203 return null;
204 }
205 } // while
206 if (m != null) {
207 Object []args = {request};
208 try {
209 response = (Element)m.invoke(this, args);
210
211 } catch (Exception e) {
212 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());
213 return null;
214 }
215 } else {
216 System.err.println("ServiceRack.process: method "+method_name+" not found for class "+this.getClass().getName());
217 }
218 if (response !=null) {
219 mainResult.appendChild(doc_.importNode(response, true));
220 }
221
222 } catch (ClassNotFoundException e) {
223 System.err.println("ServiceRack error: Element class not found");
224 return null;
225 }
226 } else {
227 // else error in to field
228 System.err.println("ServiceRack describe request: error in 'to' field, non-existant service "+to+" specified!");
229 return null;
230 }
231 }
232 } // for each request
233
234 return mainResult;
235
236 }
237
238 /** process method for describe requests
239 */
240 protected Element processDescribe(Element request) {
241
242 Element response = doc_.createElement(GSXML.RESPONSE_ELEM);
243 response.setAttribute(GSXML.TYPE_ATT, GSXML.REQUEST_TYPE_DESCRIBE);
244
245 String lang = request.getAttribute(GSXML.LANG_ATT);
246 String info = request.getAttribute(GSXML.INFO_ATT);
247 String to = GSPath.getFirstLink(request.getAttribute(GSXML.TO_ATT));
248
249 if (to.equals("")) { // to="", look at info
250 if (info.equals(GSXML.SERVICE_ELEM+GSXML.LIST_MODIFIER)) {
251 response.appendChild(getServiceList(lang));
252 return response;
253 }
254 // else error in info field
255 System.err.println("ServiceRack describe request: error in 'info' field, info='"+info+"'.");
256 return null;
257 }
258
259 // describe a particular service
260 if (service_info_map_.containsKey(to)) {
261 response.appendChild(getServiceDescription(to, lang));
262 response.setAttribute(GSXML.FROM_ATT, to);
263 return response;
264 }
265 // else error in to field
266 System.err.println("ServiceRack describe request: error in 'to' field, to='"+to+"'.");
267 return null;
268
269 }
270
271 /** process method for stylesheet requests
272 */
273 protected Element processFormat(Element request) {
274 Element response = doc_.createElement(GSXML.RESPONSE_ELEM);
275 response.setAttribute(GSXML.TYPE_ATT, GSXML.REQUEST_TYPE_FORMAT);
276
277 String to = GSPath.getFirstLink(request.getAttribute(GSXML.TO_ATT));
278
279 if (to.equals("")) { // serviceRack query - is this appropriate??
280 return response;
281 }
282
283
284 // describe a particular service
285 if (format_info_map_.containsKey(to)) {
286 response.appendChild(getServiceFormat(to));
287 response.setAttribute(GSXML.FROM_ATT, to);
288 return response;
289 }
290 // else error in to field
291 System.err.println("ServiceRack describe request: no format info for "+to+".");
292 return response;
293 }
294
295 // the following two should be overwritten for info with any language stuff in it
296 /** returns the service list for the subclass */
297 protected Element getServiceList(String lang) {
298 // for now, it is static and there is no lang stuff
299 return short_service_info_;
300 }
301
302 /** returns a specific service description */
303 protected Element getServiceDescription(String service, String lang) {
304 Element descript = (Element)((Element)service_info_map_.get(service)).cloneNode(true);
305 // for now, create the display element on the fly - look at caching it later
306 Element display = createServiceDisplay(service, lang);
307 addServiceDisplay(descript, display);
308 return descript;
309 }
310
311
312 /** adds the display element into the description - appends to the root for now, but may do something fancy later */
313 protected boolean addServiceDisplay(Element descript, Element display) {
314 if (descript.getOwnerDocument() != display.getOwnerDocument()) {
315 display = (Element)descript.getOwnerDocument().importNode(display, true);
316 }
317 descript.appendChild(display);
318 return true;
319 }
320
321 protected Element getServiceFormat(String service) {
322 Element format = (Element)((Element)format_info_map_.get(service)).cloneNode(true);
323 return format;
324 }
325 /** creates a display element containing all the text strings needed to display the service page, in the language specified */
326 abstract protected Element createServiceDisplay(String service, String lang);
327
328 /** overloaded version for no args case */
329 protected String getTextString(String key, String lang) {
330 return getTextString(key, null, lang);
331 }
332 /** getTextString - retrieves a language specific text string for the given
333key and locale
334 */
335 protected String getTextString(String key, String[] args, String lang) {
336
337 String class_name = this.getClass().getName();
338 class_name = class_name.substring(class_name.lastIndexOf('.')+1);
339
340 Dictionary dict = new Dictionary(class_name, lang);
341 String result = dict.get(key, args);
342 if (result == null) { // not found
343 return "_"+key+"_";
344 }
345 return result;
346 }
347}
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