1
|
package eu.dnetlib.enabling.is.sn;
|
2
|
|
3
|
import java.io.StringWriter;
|
4
|
import java.util.Collection;
|
5
|
|
6
|
import javax.xml.transform.Transformer;
|
7
|
import javax.xml.transform.TransformerException;
|
8
|
import javax.xml.transform.TransformerFactory;
|
9
|
import javax.xml.transform.dom.DOMSource;
|
10
|
import javax.xml.transform.stream.StreamResult;
|
11
|
import javax.xml.xpath.XPath;
|
12
|
import javax.xml.xpath.XPathConstants;
|
13
|
import javax.xml.xpath.XPathExpressionException;
|
14
|
import javax.xml.xpath.XPathFactory;
|
15
|
|
16
|
import org.apache.commons.logging.Log;
|
17
|
import org.apache.commons.logging.LogFactory;
|
18
|
import org.w3c.dom.Node;
|
19
|
|
20
|
import eu.dnetlib.enabling.is.sn.resourcestate.ResourceStateNotificationDetector;
|
21
|
import eu.dnetlib.enabling.is.sn.resourcestate.ResourceStateSubscription;
|
22
|
import eu.dnetlib.enabling.is.sn.resourcestate.ResourceStateSubscriptionRegistry;
|
23
|
import eu.dnetlib.enabling.tools.OpaqueResource;
|
24
|
|
25
|
/**
|
26
|
* This notification detector uses a local xmldb trigger as a source of events.
|
27
|
*
|
28
|
* @author marko
|
29
|
*
|
30
|
*/
|
31
|
public class NotificationDetectorImpl extends AbstractNotificationDetector implements ResourceStateNotificationDetector<OpaqueResource> {
|
32
|
|
33
|
/**
|
34
|
* logger.
|
35
|
*/
|
36
|
private static final Log log = LogFactory.getLog(NotificationDetectorImpl.class); // NOPMD by marko on 11/24/08 5:02 PM
|
37
|
|
38
|
/**
|
39
|
* subscription registries to lookup.
|
40
|
*/
|
41
|
private SubscriptionRegistry registry;
|
42
|
|
43
|
/**
|
44
|
* {@inheritDoc}
|
45
|
*
|
46
|
* @see eu.dnetlib.enabling.is.sn.resourcestate.ResourceStateNotificationDetector#resourceCreated(java.lang.Object)
|
47
|
*/
|
48
|
@Override
|
49
|
public void resourceCreated(final OpaqueResource newResource) {
|
50
|
log.debug("resource created: " + getRegistry());
|
51
|
|
52
|
final Collection<ResourceStateSubscription> subs =
|
53
|
getRegistry().listMatchingSubscriptions(ResourceStateSubscription.PREFIX_CREATE, newResource.getResourceType(), newResource.getResourceId());
|
54
|
for (ResourceStateSubscription sub : subs) {
|
55
|
if (matchPath(newResource, sub.getXpath())) {
|
56
|
send(sub, newResource, ResourceStateSubscription.PREFIX_CREATE);
|
57
|
}
|
58
|
}
|
59
|
}
|
60
|
|
61
|
/**
|
62
|
* helper method. sends a notification for a given prefix.
|
63
|
*
|
64
|
* @param sub
|
65
|
* subscription
|
66
|
* @param resource
|
67
|
* resource
|
68
|
* @param prefix
|
69
|
* prefix
|
70
|
*/
|
71
|
private void send(final ResourceStateSubscription sub, final OpaqueResource resource, final String prefix) {
|
72
|
log.debug("RESOURCE " + resource);
|
73
|
log.debug("id: " + resource.getResourceId());
|
74
|
log.debug("dom: " + resource.asDom());
|
75
|
|
76
|
final StringBuffer topicBuffer = new StringBuffer();
|
77
|
|
78
|
if (sub.getPrefix() == null && "*".equals(sub.getPrefix()))
|
79
|
topicBuffer.append(prefix);
|
80
|
else
|
81
|
topicBuffer.append(sub.getPrefix());
|
82
|
|
83
|
topicBuffer.append('.');
|
84
|
topicBuffer.append(sub.getType());
|
85
|
topicBuffer.append('.');
|
86
|
topicBuffer.append(sub.getResourceId());
|
87
|
if (sub.getXpath() != null && !sub.getXpath().isEmpty()) {
|
88
|
topicBuffer.append(sub.getXpath().replace('/', '.'));
|
89
|
}
|
90
|
|
91
|
getSender().send(sub.getSubscriberAsEpr(), new NotificationMessage(sub.getSubscriptionId(), topicBuffer.toString(), resource.getResourceId(), // NOPMD
|
92
|
resource.asString()));
|
93
|
}
|
94
|
|
95
|
/**
|
96
|
* {@inheritDoc}
|
97
|
*
|
98
|
* @see eu.dnetlib.enabling.is.sn.resourcestate.ResourceStateNotificationDetector#resourceDeleted(java.lang.Object)
|
99
|
*/
|
100
|
@Override
|
101
|
public void resourceDeleted(final OpaqueResource oldResource) {
|
102
|
log.debug("resource deleted: " + getRegistry());
|
103
|
|
104
|
final Collection<ResourceStateSubscription> subs =
|
105
|
registry.listMatchingSubscriptions(ResourceStateSubscription.PREFIX_DELETE, oldResource.getResourceType(), oldResource.getResourceId());
|
106
|
for (ResourceStateSubscription sub : subs) {
|
107
|
if (matchPath(oldResource, sub.getXpath())) {
|
108
|
send(sub, oldResource, ResourceStateSubscription.PREFIX_DELETE);
|
109
|
}
|
110
|
}
|
111
|
}
|
112
|
|
113
|
/**
|
114
|
* {@inheritDoc}
|
115
|
*
|
116
|
* @see eu.dnetlib.enabling.is.sn.resourcestate.ResourceStateNotificationDetector#resourceUpdated(java.lang.Object,
|
117
|
* java.lang.Object)
|
118
|
*/
|
119
|
@Override
|
120
|
public void resourceUpdated(final OpaqueResource oldResource, final OpaqueResource newResource) {
|
121
|
log.debug("resource updated: " + getRegistry());
|
122
|
|
123
|
final Collection<ResourceStateSubscription> subs =
|
124
|
registry.listMatchingSubscriptions(ResourceStateSubscription.PREFIX_UPDATE, oldResource.getResourceType(), oldResource.getResourceId());
|
125
|
for (ResourceStateSubscription sub : subs) {
|
126
|
if (comparePath(oldResource, newResource, sub.getXpath())) {
|
127
|
log.debug("updated, sending: " + newResource.asString());
|
128
|
send(sub, newResource, ResourceStateSubscription.PREFIX_UPDATE);
|
129
|
}
|
130
|
}
|
131
|
}
|
132
|
|
133
|
/**
|
134
|
* check if an xpath matches a given resource.
|
135
|
*
|
136
|
* @param resource
|
137
|
* resource
|
138
|
* @param xpath
|
139
|
* xpath
|
140
|
* @return true if the resource has some value for the given path
|
141
|
*/
|
142
|
private boolean matchPath(final OpaqueResource resource, final String xpath) {
|
143
|
// by convention empty xpath matches any document
|
144
|
if (xpath == null || xpath.isEmpty())
|
145
|
return true;
|
146
|
|
147
|
final XPath xpa = XPathFactory.newInstance().newXPath();
|
148
|
try {
|
149
|
return !xpa.evaluate(xpath, resource.asDom()).isEmpty();
|
150
|
} catch (XPathExpressionException e) {
|
151
|
log.warn("wrong xpath expression, notification possibly missed", e);
|
152
|
}
|
153
|
return false;
|
154
|
}
|
155
|
|
156
|
/**
|
157
|
* compare the content of two profiles for the same xpath. Return true if some change has been made so that the
|
158
|
* notification can be delivered.
|
159
|
*
|
160
|
* @param oldResource
|
161
|
* old version
|
162
|
* @param newResource
|
163
|
* new version
|
164
|
* @param xpath
|
165
|
* XPath
|
166
|
* @return true if the two documents differ under a given path
|
167
|
*/
|
168
|
private boolean comparePath(final OpaqueResource oldResource, final OpaqueResource newResource, final String xpath) {
|
169
|
// by convention empty xpath matches any document
|
170
|
if (oldResource == null || newResource == null || xpath == null || xpath.isEmpty())
|
171
|
return true;
|
172
|
|
173
|
final XPath xpa = XPathFactory.newInstance().newXPath();
|
174
|
try {
|
175
|
final Transformer transformer = TransformerFactory.newInstance().newTransformer();
|
176
|
|
177
|
final Node left = (Node) xpa.evaluate(xpath, oldResource.asDom(), XPathConstants.NODE);
|
178
|
final Node right = (Node) xpa.evaluate(xpath, newResource.asDom(), XPathConstants.NODE);
|
179
|
|
180
|
if (left==null || right==null) {
|
181
|
if (left != null) {
|
182
|
return true;
|
183
|
}
|
184
|
else {
|
185
|
if (right != null) {
|
186
|
return true;
|
187
|
}
|
188
|
else {
|
189
|
return false;
|
190
|
}
|
191
|
}
|
192
|
}
|
193
|
|
194
|
final StringWriter leftWriter = new StringWriter();
|
195
|
final StringWriter rightWriter = new StringWriter();
|
196
|
|
197
|
transformer.transform(new DOMSource(left), new StreamResult(leftWriter));
|
198
|
transformer.transform(new DOMSource(right), new StreamResult(rightWriter));
|
199
|
|
200
|
return !leftWriter.toString().equals(rightWriter.toString());
|
201
|
} catch (XPathExpressionException e) {
|
202
|
log.warn("wrong xpath expression, notification possibly missed", e);
|
203
|
} catch (TransformerException e) {
|
204
|
log.warn("serialization problem", e);
|
205
|
}
|
206
|
|
207
|
return false;
|
208
|
}
|
209
|
|
210
|
public SubscriptionRegistry getRegistry() {
|
211
|
return registry;
|
212
|
}
|
213
|
|
214
|
public void setRegistry(final SubscriptionRegistry registry) {
|
215
|
this.registry = registry;
|
216
|
}
|
217
|
}
|