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From Fraser Adams <fraser.ad...@blueyonder.co.uk>
Subject Re: How to test Qpid c++ broker ?
Date Fri, 23 Aug 2013 13:39:35 GMT
I guess that one thing you might want to bear in mind is 
interoperability, for example say your producer clients are C++ based 
and consumers are say Java based.

Am I not right in thinking that setting content-type in a C++ client 
causes a particular mapping when deserialised in Java so text/plain 
winds up as a TextMessage, amqp/map as a MapMessage?, amqp/list as .... 
well best not start me off on that again :-)

I *guess* that it's possibly/probably the case that setting to something 
that isn't one of those might cause a default ByesMessage mapping (which 
would make sense to me) so say "image/jpeg" would probably end up as 
BytesMessage content with the content-type available in JMSType (I think 
- it used to be necessary to down cast do a Qpid specific class to get 
the content-type but I think recent versions of Qpid have this available 
in JMSType, but I'm not sure the version this behaviour became available)

TBH I generally send data as opaque BytesMessage unless I'm doing QMF2 
stuff and I mostly use Java so I haven't really tried out what exciting 
effects occur with C++ producers and Java consumers so I may be 
completely off the mark, but TBH I'd quite like to know myself for 
future reference.

Frase



On 23/08/13 13:44, Gordon Sim wrote:
> On 08/23/2013 12:33 PM, kevency_poche wrote:
>> i will work on those and get back to you. the spout and drain 
>> executables
>> are useful to send some text. If i want to send something like 
>> images,audio,
>> etc. Is it possible using this c++ broker ?
>> Excuse me, if this is a silly question .
>
> Not a silly question at all. The fact that the content is set as a 
> std::string doesn't imply that it is textual in nature. It is 
> essentially just a sequence of bytes. So yes it is certainly possible.
>
> For AMQP 0-10 you can set the content-type to 'text/plain' to indicate 
> that it is textual data, and of course you could set that to some 
> other mime-type to indicate some other binary form (e.g. image/jpeg or 
> whatever).
>
> In future there will be an extension to the API (already on trunk, but 
> won't be released until 0.26), that lets you set the content as an 
> object (a qpid::types::Variant). That allows the std::string to be 
> associated with an encoding (utf8, ascii or binary), as well as 
> allowing it to be a map, list, uuid or one of various numeric types.
>
> In hindsight the API would likely have been clearer had 
> std::vector<uint8_t> been used in place of std::string. That may be an 
> addition that gets made at some point also.
>
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