/**
* Checks if the given {@linkplain JID} supports the requested feature. The JID may be non
* resource qualified in which case all presences belonging to that JID are checked.
*
* <p>This method does <b>not</b> perform any I/O operation and will return immediately.
*
* <p><b>Please note the return value: <code>if(isFeatureSupported(foo, bar)) ... </code> is
* likely to produce a {@link NullPointerException NPE}.</b>
*
* @param jid {@link JID} to query support for
* @param namespace the namespace of the feature
* @return <code>true</code> if the given feature is supported, <code>false</code> if it is not
* supported or <b><code>null</code> </b> if no information is available
* @see #queryFeatureSupport(JID, String, boolean)
*/
public Boolean isFeatureSupported(final JID jid, final String namespace) {
checkJID(jid);
Boolean supported = null;
final List<JID> jidsToQuery = new ArrayList<JID>();
if (jid.isBareJID()) jidsToQuery.addAll(rosterTracker.getAvailablePresences(jid));
else jidsToQuery.add(jid);
for (JID rqJID : jidsToQuery) {
DiscoverInfoWrapper info = cache.get(rqJID.toString());
if (info == null) continue;
DiscoverInfo disco = info.item;
if (disco == null) continue;
supported = disco.containsFeature(namespace);
if (supported) break;
}
return supported;
}
/**
* Perform a service discovery and check if the given feature is among the features supported by
* the given recipient. All registered listeners will be notified about the result.
*
* @param jid A RQ-JID (user@host/resource) of the user to query support for or a non RQ-JID to
* query all presences for this JID.
* @blocking This method blocks until the ServiceDiscovery returns.
* @reentrant This method can be called concurrently.
* @caching If results are available in the cache, they are used instead of querying the server.
*/
private Boolean queryFeatureSupport(JID jid, String namespace) {
Boolean supported = null;
checkJID(jid);
DiscoverInfoWrapper wrapper;
final List<JID> jidsToQuery = new ArrayList<JID>();
if (jid.isBareJID()) jidsToQuery.addAll(rosterTracker.getAvailablePresences(jid));
else jidsToQuery.add(jid);
for (JID rqJID : jidsToQuery) {
// add dummy
synchronized (cache) {
wrapper = cache.get(rqJID.toString());
if (wrapper == null) {
wrapper = new DiscoverInfoWrapper();
cache.put(rqJID.toString(), wrapper);
}
}
DiscoverInfo disco = null;
// wait if there is already a discovery for the JID in progress
synchronized (wrapper) {
if (wrapper.isAvailable()) disco = wrapper.item;
else {
disco = wrapper.item = performServiceDiscovery(rqJID);
if (disco != null) LOG.debug("Inserted DiscoveryInfo into Cache for: " + rqJID);
}
}
// Null means that the discovery failed
if (disco == null) {
// and so we do not know if the feature is supported
// notifyFeatureSupportUpdated(jid, namespace, false);
continue;
}
notifyFeatureSupportUpdated(rqJID, namespace, disco.containsFeature(namespace));
/*
* loop through all presence regardless if we already know that the
* feature is supported to notify the listener for every current
* presence
*/
if (supported != null) supported |= disco.containsFeature(namespace);
else supported = disco.containsFeature(namespace);
}
return supported;
}
/**
* Perform a ServiceDiscovery [1] and check if the given resource is among the features supported
* by the given recipient.
*
* <p>[1] XEP-0030 http://xmpp.org/extensions/xep-0030.html
*
* @param jid The JID must have a resource identifier (user@host/resource), otherwise you get a
* blame StackTrace in your logs.
* @return DiscoverInfo from recipient or null if an XMPPException was thrown.
* @blocking This method blocks until the ServiceDiscovery returns.
* @reentrant This method can be called concurrently.
* @nonCaching This method does not use a cache, but queries the server directly.
*/
private DiscoverInfo performServiceDiscovery(final JID jid) {
if (jid.isBareJID()) {
LOG.warn(
"cannot perform service discovery on a non resource qualified jid: " + jid.toString(),
new StackTrace());
return null;
}
final Connection connection = connectionService.getConnection();
if (connection == null) {
LOG.warn("cannot not perform a service discovery because not connected to a XMPP server");
return null;
}
ServiceDiscoveryManager sdm = ServiceDiscoveryManager.getInstanceFor(connection);
try {
return sdm.discoverInfo(jid.toString());
} catch (XMPPException e) {
LOG.warn(
"Service Discovery failed on recipient "
+ jid.toString()
+ " server: "
+ connection.getHost(),
e);
/*
* FIXME handle timeouts and error conditions differently ! see
* http://xmpp.org/extensions/xep-0030.html#errors
*/
return null;
}
}