Asynchronous message delivery

An asynchronous put to a remote queue places the message on the backing store associated with the local definition of that queue, along with its destination queue manager name, queue name, and the compressor, authenticator, and cryptor characteristics that match the target destination of the message. The message's dump method is called as it is saved to persistent storage in a secure format that is defined by its destination queue. The queue manager controls message delivery. It identifies or establishes a connection with appropriate characteristics to the queue manager for the next hop, then creates or reuses a transporter to the target queue manager. The transporter dumps the message and transmits the resulting byte string. The target queue manager and queue name are not part of that message flow.

If appropriate, the message is encrypted and compressed over the connection. If it has reached its destination queue manager, it is decrypted and decompressed. A new message is created, using the restore method, and the resultant message is placed on the destination queue. If the message has not reached its destination queue manager, it is decrypted and decompressed. It is then re-encrypted, compressed, and placed on a store-and-forward queue for onward transmission, if a store-and-forward queue exists. In both cases it is held on its respective queue in a secure format, as defined by its destination queue.

A characteristic of asynchronous message delivery is that messages are passed to the queue manager at intermediate hops, being queued for onward transmission. Messages are taken off the intermediate queues first in order of priority, then in order of arrival on the queue. Duplicate messages, created when you resend a message, are also taken off the intermediate queues in the order of their arrival on the queue.


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