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From John Dennis <jden...@redhat.com>
Subject Re: remote byte-order
Date Thu, 17 Sep 2009 12:57:45 GMT
On 09/17/2009 07:48 AM, Bill Whiting wrote:
> On 09/17/2009 03:47 AM, Gordon Sim wrote:
>> On 09/16/2009 07:34 PM, Bill Whiting wrote:
>>> I'm replacing other messaging with qpid. I have code for marshalling
>>> and demarshalling data that uses byte-order to know how to handle
>>> integers. I can add a custom property to the message that provides byte
>>> order, but it would be preferrable to have the byte-order of the sender
>>> implemented in the API.
>>
>> I'm not as convinced. It doesn't seem like the sort of information
>> that most applications will want automatically included in their
>> headers which means you would need some mechanism to enable it, and in
>> that case are you really gaining much?
>>
>> In the general case the content type would need to be set by the
>> application anyway, to let the receivers know the format. Appending
>> information on the byte-order to that seems like a reasonable approach
>> to me since it is relevant only to the decoding.
> Why not enable this for all applications? If an application doesn't need
> or want the information it won't hurt to have it along for the ride.

I'm not convinced either. You've essentially got a private protocol 
inside an AMQP content block. Most network protocols handle byte order 
on their own. They either write in network byte order or they include a 
byte order marker in the protocol. You can either add an application 
specific header as metadata to the AMQP message to convey the sender's 
byte order, or follow the conventional network protocol practices noted 
above (which would be of benefit if you ever use a transport other than 
AMQP). None of this requires a change to AMQP, which seems like a 
minority case, especially since it appears you're not following best 
practice in your private embedded protocol to begin with.

-- 
John Dennis <jdennis@redhat.com>

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