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From Gordon Sim <g...@redhat.com>
Subject Re: How can you do at-least-one in federated broker?
Date Wed, 02 Nov 2011 09:49:41 GMT
On 11/01/2011 09:09 PM, Daryoush Mehrtash wrote:
> Is there a notion of negative ack?    For instance, if the destination
> broker gets a message that is corrupted, can it n-ack it?

There is such a mechanism in AMQP, but the inter-broker routing does not 
use it. Brokers can't detect corruption of the message bodies - they are 
treated as opaque byte sequences - and they treat any malformed frames 
as a client error and terminate the connection.

> General question.....  I am confused as to extend to which AQMP defines the
> interactions.   It seems that it does defined the client to broker but I am
> not sure about inter-broker protocol.   Is the protocol between the brokers
> also defined in AQMP?

The protocol used between the brokers is compliant AMQP 0-10[1]. One 
broker is treated as a client of the other (in fact other than for 
setting up the connection, each broker views the other as a regular 
client[2]). Setting up the links is done through Qpid specific 
management commands however.

[1] There is one minor exception to this rule, a defect in the 
implementation rather than a concious design choice, whereby the broker 
does not attach the session for 'push routes' in a compliant manner.

[2] There is a qpid specific property that is set on a connection to 
indicate that it is a connection from another broker. This is used to 
allow transfer of message with a userid other than that used for the link.

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