public interface: MessageQuery
Represents some kind of query which will load initial messages from some source for a new topic subscriber.
$ - Revision: 564271 $
|Method from org.apache.activemq.broker.region.policy.MessageQuery Detail:|
public void execute(ActiveMQDestination destination,
MessageListener listener) throws Exception
Executes the query for messages; each message is passed into the listener
public boolean validateUpdate(Message message)
Returns true if the given update is valid and does not overlap with the initial message query.
When performing an initial load from some source, there is a chance that an update may occur which is logically before
the message sent on the initial load - so this method provides a hook where the query instance can keep track of the version IDs
of the messages sent so that if an older version is sent as an update it can be excluded to avoid going backwards in time.
e.g. if the execute() method creates version 2 of an object and then an update message is sent for version 1, this method should return false to
hide the old update message.