Hi Nigel - great email as usual :) , - inlined:
>
> QUESTIONS
>
> 1. Which is better, using a BatchMessageListener or allowing the server to create BatchMessage objects?
BatchMessages for reasons you've outlined :)
>
> 2. I'm currently suggesting that BatchMessage objects would never be created by the application, They would simply be a convenient container object that the JMS provider could use when delivering batches of messages. However we could if we wanted allow the producer client to create them and use them to send batches of messages to the server, which would then break them down into their constituent messages before adding to the destination. Would this have any benefit?
This would be of benefit - would be more efficient than sending individual messages in a transaction - which would be the way to currently do it
>
> 3. Should we take advantage of BatchMessage objects to allow the server to deliver messages in batches to a synchronous consumer?
Yes - I don't see why you wouldn't want this capability
>
> ==================================================================================
>
> SUMMARY OF PROPOSAL
>
> THE NEW BatchMessage CLASS
>
> /** An <CODE>BatchMessage</CODE> object is a special type of message which can be
> * created by the JMS provider and used to deliver an ordered batch of ordinary
> * messages to a consumer. It inherits from the <CODE>Message</CODE> interface
> * and adds methods to allow the individual messages to be extracted.
> *
> * Note that this message type is created by the JMS provider, not by
> * the application, and therefore only provides public methods to
> * extract messages, not to set them.
> *
> * @see javax.jms.ObjectMessage
> * @see javax.jms.BytesMessage
> * @see javax.jms.MapMessage
> * @see javax.jms.Message
> * @see javax.jms.StreamMessage
> * @see javax.jms.TextMessage
> */
>
> public interface BatchMessage extends Message {
>
> /**
> * returns the number of messages in this BatchMessage
> *
> * @return the number of messages in this BatchMessage
> *
> * @throws JMSException if the JMS provider fails to get the size due to some internal error
> */
> int size() throws JMSException;
>
> /**
> * returns the Message at the specified position in the batch
> * @param index index of the Messagr to return
> *
> * @return the Message at the specified position in the batch
> *
> * @throws JMSException if the JMS provider fails to get the Message due to some internal error
> */
> Message get(int index) throws JMSException;
> }
>
> NEW METHODS ON Session FOR CREATING A MESSAGE CONSUMER
>
> In addition, two new methods on Session would be needed to allow the batch size and timeout when creating a MessageConsumer:
>
> MessageConsumer createConsumer(Destination destination, String messageSelector, boolean NoLocal, int maxBatchSize, long batchTimeout)
>
> MessageConsumer createDurableConsumer(Topic topic, String name, String messageSelector, boolean noLocal, int maxBatchSize, long batchTimeout)
>
> NEW METHODS ON MessagingContext FOR SETTING A MESSAGE LISTENER
>
> We would need similar new methods on MessagingContext. You will remember that this currently offers methods to set the message listener directly, five for MessageListener and five for BatchMessageListener, making ten in total.
>
> We would drop the latter five, and add two new methods methods (one for queues and non-durable subscriptions and one for durable subscriptions) to allow batch size and timeout to be supplied, making seven in total:
>
> setMessageListener(Destination destination, String messageSelector, boolean noLocal, int maxBatchSize, long batchTimeout, MessageListener listener)
>
> setMessageListener(Topic topic, String subscriptionName, String messageSelector, boolean noLocal, int maxBatchSize, long batchTimeout, MessageListener listener)
>
> NEW METHODS ON MessagingContext FOR CREATING A SYNC MESSAGE CONSUMER
>
> If we wanted to extend this feature to synchronous consumers we would also add two new methods for creating a SyncMessageConsumer (one for queues and non-durable subscriptions and one for durable subscriptions):
>
> SyncMessageConsumer createSyncConsumer(Destination destination, String messageSelector, boolean noLocal, int maxBatchSize, long batchTimeout)
>
> SyncMessageConsumer createSyncDurableConsumer(Topic topic, String name, String messageSelector, boolean noLocal, int maxBatchSize, long batchTimeout)
>
> ==================================================================================
>
> I hope this is clear! If not, please let me know.
>
> Nigel
>