All changes done in a Strolch transaction are recorded and then propagated to any registered observers.
The observer feature is opt-in and is configured for each realm. In the
StrolchConfiguration.xml file enable observers by adding the
enableObserverUpdates property per realm:
<StrolchConfiguration>
<env id="dev">
...
<Component>
<name>RealmHandler</name>
<api>li.strolch.agent.api.RealmHandler</api>
<impl>li.strolch.agent.impl.DefaultRealmHandler</impl>
<depends>PrivilegeHandler</depends>
<Properties>
<realms>defaultRealm, otherRealm</realms>
<enableObserverUpdates>true</enableObserverUpdates>
<dataStoreMode>TRANSIENT</dataStoreMode>
<dataStoreFile>StrolchModel.xml</dataStoreFile>
<enableObserverUpdates.otherRealm>true</enableObserverUpdates.otherRealm>
<dataStoreMode.otherRealm>TRANSIENT</dataStoreMode.otherRealm>
<dataStoreFile.otherRealm>StrolchModel.xml</dataStoreFile.otherRealm>
</Properties>
</Component>
</env>
...
</StrolchConfiguration>
Registering for updates is done by registering an Observer on the ObserverHandler of the realm itself:
public class Example {
public static void main(String[] args) {
ObserverHandler observerHandler = container
.getRealm(StrolchConstants.DEFAULT_REALM).getObserverHandler();
observerHandler.registerObserver(Tags.RESOURCE, new Observer() {
@Override
public void update(String key, List<StrolchRootElement> elements) {
logger.info(elements.size() + " resources were updated!");
}
@Override
public void remove(String key, List<StrolchRootElement> elements) {
logger.info(elements.size() + " resources were removed!");
}
@Override
public void add(String key, List<StrolchRootElement> elements) {
logger.info(elements.size() + " resources were added!");
}
});
}
}