source: trunk/gsdl3/src/java/org/greenstone/gsdl3/service/ServiceRack.java@ 10088

Last change on this file since 10088 was 10088, checked in by kjdon, 19 years ago

now keep a reference to the class loader
  • Property svn:keywords set to Author Date Id Revision
File size: 13.5 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: 10088 $
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 http address of the site home */
63 protected String site_http_address =null;
64
65 /** the name of the cluster (or collection) that this service
66 belongs to - if any */
67 protected String cluster_name = null;
68
69 /** some services can talk back to the message router */
70 protected ModuleInterface router = null;
71
72 /** a converter class to create Documents etc */
73 protected XMLConverter converter = null;
74
75 /** the original config info - if need to store it */
76 protected Element config_info = null;
77
78 /** XML element for describe requests - the container doc */
79 protected Document doc = null;
80
81 /** XML element for describe requests - list of supported services
82 - this is static */
83 protected Element short_service_info = null;
84
85 /** XML element for stylesheet requests - map of service name to format
86 elem */
87 protected HashMap format_info_map = null;
88
89 /** A class loader that knows about the collection resources directory
90 * can put properties files, dtds etc in here */
91 CollectionClassLoader class_loader = null;
92
93 /** sets the cluster name */
94 public void setClusterName(String cluster_name) {
95 this.cluster_name = cluster_name;
96 }
97 /** sets the collect name */
98 public void setCollectionName(String coll_name) {
99 setClusterName(coll_name);
100 }
101
102 public void cleanUp() {}
103
104 /** sets the site home */
105 public void setSiteHome(String site_home) {
106 this.site_home = site_home;
107 }
108 /** sets the site http address */
109 public void setSiteAddress(String site_address) {
110 this.site_http_address = site_address;
111 }
112
113 /** sets the message router */
114 public void setMessageRouter(ModuleInterface m) {
115 this.router = m;
116 }
117
118 /** the no-args constructor */
119 public ServiceRack() {
120 this.converter = new XMLConverter();
121 this.doc = this.converter.newDOM();
122 this.short_service_info = this.doc.createElement(GSXML.SERVICE_ELEM+GSXML.LIST_MODIFIER);
123 this.format_info_map = new HashMap();
124 }
125
126
127 /** configure the service module
128 *
129 * @param info the XML node <serviceRack name="XXX"/> with name equal
130 * to the class name (of the subclass)
131 *
132 * must configure short_service_info_ and service_info_map_
133 * @return true if configured ok
134 * must be implemented in subclasses
135 */
136 public boolean configure(Element info) {
137 // set up the class loader
138 this.class_loader = new CollectionClassLoader(this.getClass().getClassLoader(), this.site_home, this.cluster_name);
139
140 return configure(info, null);
141 }
142
143 abstract public boolean configure(Element info, Element extra_info);
144
145 /**
146 * Process an XML document - convenience method that uses Strings rather than Elements. just calls process(Element).
147 *
148 * @param xml_in the Document to process - a string
149 * @return the resultant document as a string - contains any error messages
150 * @see String
151 */
152 public String process(String xml_in) {
153
154 Document doc = this.converter.getDOM(xml_in);
155 if (doc == null) {
156 System.err.println("ServiceRack.process(String) Error: Couldn't parse request");
157 System.err.println(xml_in);
158 return null;
159 }
160 Element res = process(doc.getDocumentElement());
161 return this.converter.getString(res);
162
163 }
164
165 /** process an XML request in DOM form
166 *
167 * @param xml_in the Element node containing the request
168 * should be <message>
169 * @return an Element with the result XML
170 * @see Element
171 */
172 public Element process(Element message) {
173
174 NodeList requests = message.getElementsByTagName(GSXML.REQUEST_ELEM);
175 Document mess_doc = message.getOwnerDocument();
176 Element mainResult = this.doc.createElement(GSXML.MESSAGE_ELEM);
177 if (requests.getLength()==0) {
178 // no requests
179 return mainResult; // empty message for now
180 }
181
182 for (int i=0; i<requests.getLength(); i++) {
183 Element request = (Element)requests.item(i);
184
185 String type = request.getAttribute(GSXML.TYPE_ATT);
186 if (type.equals(GSXML.REQUEST_TYPE_DESCRIBE)) {
187 Element response = processDescribe(request);
188 if (response !=null) {
189 mainResult.appendChild(this.doc.importNode(response, true));
190 }
191
192 } else if (type.equals(GSXML.REQUEST_TYPE_FORMAT)) {
193 Element response = processFormat(request);
194 mainResult.appendChild(this.doc.importNode(response, true));
195
196
197 } else {
198 // other type of request, must be processed by the subclass -
199 // send to the service method
200 StringBuffer error_string = new StringBuffer();
201 String to = GSPath.getFirstLink(request.getAttribute(GSXML.TO_ATT));
202 Element response = null;
203 try {
204 Class c = this.getClass();
205 Class []params = {Class.forName("org.w3c.dom.Element")};
206
207 String method_name = "process"+to;
208 Method m = null;
209 while (c != null) {
210
211 try {
212 m = c.getDeclaredMethod(method_name, params);
213 // if this has worked, break
214 break;
215 } catch (NoSuchMethodException e) {
216 c = c.getSuperclass();
217 } catch (SecurityException e) {
218 System.err.println("ServiceRack.process: security exception for finding method "+method_name);
219 error_string.append("ServiceRack.process: security exception for finding method "+method_name);
220 }
221 } // while
222 if (m != null) {
223 Object []args = {request};
224 try {
225 response = (Element)m.invoke(this, args);
226
227 } catch (Exception e) {
228 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());
229 error_string.append("ServiceRack.process: Trying to call a processService type method (process"+to+") on a subclass("+this.getClass().getName()+"), but an exception happened:"+e.toString());
230 }
231 } else {
232 System.err.println("ServiceRack.process: method "+method_name+" not found for class "+this.getClass().getName());
233 error_string.append("ServiceRack.process: method "+method_name+" not found for class "+this.getClass().getName());
234 }
235
236 } catch (ClassNotFoundException e) {
237 System.err.println("ServiceRack error: Element class not found");
238 error_string.append("ServiceRack error: Element class not found");
239 }
240 if (response !=null) {
241 mainResult.appendChild(this.doc.importNode(response, true));
242 } else {
243 // add in a dummy response
244 System.err.println("adding in an error element\n");
245 response = this.doc.createElement(GSXML.RESPONSE_ELEM);
246 GSXML.addError(this.doc, response, error_string.toString());
247 mainResult.appendChild(response);
248
249 }
250
251 } // else process request
252 } // for each request
253
254 return mainResult;
255
256 }
257
258
259
260 /** process method for describe requests
261 */
262 protected Element processDescribe(Element request) {
263
264 Element response = this.doc.createElement(GSXML.RESPONSE_ELEM);
265 response.setAttribute(GSXML.TYPE_ATT, GSXML.REQUEST_TYPE_DESCRIBE);
266
267 String lang = request.getAttribute(GSXML.LANG_ATT);
268 String to = GSPath.getFirstLink(request.getAttribute(GSXML.TO_ATT));
269 if (to.equals("")) { // return the service list
270 response.appendChild(getServiceList(lang));
271 return response;
272 }
273 response.setAttribute(GSXML.FROM_ATT, to);
274 Element param_list = (Element)GSXML.getChildByTagName(request, GSXML.PARAM_ELEM+GSXML.LIST_MODIFIER);
275 Element description = null;
276 if (param_list == null) {
277 description = getServiceDescription(to, lang, null);
278 } else {
279 NodeList params = param_list.getElementsByTagName(GSXML.PARAM_ELEM);
280 for (int i=0; i<params.getLength(); i++) {
281
282 Element param = (Element)params.item(i);
283 // Identify the structure information desired
284 if (param.getAttribute(GSXML.NAME_ATT).equals(GSXML.SUBSET_PARAM )) {
285 String info = param.getAttribute(GSXML.VALUE_ATT);
286 if (description == null) {
287 description = getServiceDescription(to, lang, info);
288 } else {
289 Element temp = getServiceDescription(to, lang, info);
290 GSXML.mergeElements(description, temp);
291 }
292 }
293 }
294 }
295 if (description != null) { // may be null if non-existant service
296 response.appendChild(description);
297 }
298 return response;
299
300 }
301
302 /** process method for stylesheet requests
303 */
304 protected Element processFormat(Element request) {
305 Element response = this.doc.createElement(GSXML.RESPONSE_ELEM);
306 response.setAttribute(GSXML.TYPE_ATT, GSXML.REQUEST_TYPE_FORMAT);
307
308 String to = GSPath.getFirstLink(request.getAttribute(GSXML.TO_ATT));
309
310 if (to.equals("")) { // serviceRack query - is this appropriate??
311 return response;
312 }
313
314
315 // describe a particular service
316 if (this.format_info_map.containsKey(to)) {
317 response.appendChild(getServiceFormat(to));
318 response.setAttribute(GSXML.FROM_ATT, to);
319 return response;
320 }
321 // else no format info
322 System.err.println("ServiceRack describe request: no format info for "+to+".");
323 return response;
324 }
325
326 /** returns the service list for the subclass */
327 protected Element getServiceList(String lang) {
328 // for now, it is static and has no language stuff
329 return (Element) this.short_service_info.cloneNode(true);
330 }
331
332 /** returns a specific service description */
333 abstract protected Element getServiceDescription(String service, String lang, String subset);
334
335 protected Element getServiceFormat(String service) {
336 Element format = (Element)((Element)this.format_info_map.get(service)).cloneNode(true);
337 return format;
338 }
339
340 /** overloaded version for no args case */
341 protected String getTextString(String key, String lang) {
342 return getTextString(key, lang, null, null);
343 }
344
345 protected String getTextString(String key, String lang, String dictionary) {
346 return getTextString(key, lang, dictionary, null);
347 }
348 protected String getTextString(String key, String lang, String [] args) {
349 return getTextString(key, lang, null, args);
350 }
351
352 /** getTextString - retrieves a language specific text string for the given
353key and locale, from the specified resource_bundle (dictionary)
354 */
355 protected String getTextString(String key, String lang, String dictionary, String[] args) {
356
357 // we want to use the collection class loader in case there are coll specific files
358 if (dictionary != null) {
359 // just try the one specified dictionary
360 Dictionary dict = new Dictionary(dictionary, lang, this.class_loader);
361 String result = dict.get(key, args);
362 if (result == null) { // not found
363 return "_"+key+"_";
364 }
365 return result;
366 }
367
368 // now we try class names for dictionary names
369 String class_name = this.getClass().getName();
370 class_name = class_name.substring(class_name.lastIndexOf('.')+1);
371 Dictionary dict = new Dictionary(class_name, lang, this.class_loader);
372 String result = dict.get(key, args);
373 if (result != null) {
374 return result;
375 }
376
377 // we have to try super classes
378 Class c = this.getClass().getSuperclass();
379 while (result == null && c != null) {
380 class_name = c.getName();
381 class_name = class_name.substring(class_name.lastIndexOf('.')+1);
382 if (class_name.equals("ServiceRack")) {
383 // this is as far as we go
384 break;
385 }
386 dict = new Dictionary(class_name, lang, this.class_loader);
387 result = dict.get(key, args);
388 c = c.getSuperclass();
389 }
390 if (result == null) {
391 return "_"+key+"_";
392 }
393 return result;
394
395 }
396
397 protected String getMetadataNameText(String key, String lang) {
398
399 String properties_name = "metadata_names";
400 Dictionary dict = new Dictionary(properties_name, lang);
401
402 String result = dict.get(key);
403 if (result == null) { // not found
404 return null;
405 }
406 return result;
407 }
408}
409
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