On Mon, Jan 09, 2012 at 09:40:55AM +0000, Gordon Sim wrote: > On 01/06/2012 10:58 PM, William Henry wrote: > > > >I'm curious about the following: > > > >1) Why do you need to explicitly set the receiver capacity in order to > >receiver messages? You'd think that be default you'd not have to set this. > > You don't. The capacity controls the number of 'prefetched' messages > the library will accept, i.e. messages delivered by the broker > before - and in anticipation of - application calls to fetch(). > > The default is to have no prefetch, which means the broker will only > deliver a message in response to an explicit fetch() call. The > reason for this default is that it gives the most intuitive > behaviour in many cases and so is good for exploring/experimenting. > (Messages aren't hidden in prefetch queues anywhere).
One language-specific difference is that, with the non-blocking I/O extension for Ruby, the default capacity on a Receiver is 1 rather than 0. > However, if you are using next_receiver() to service several > receivers, then you do need messages to be delivered before you call > fetch() (since you don't know which of them will have messages) and > so in that case you do need to set capacity to some value greater > than zero. -- Darryl L. Pierce, Sr. Software Engineer @ Red Hat, Inc. Delivering value year after year. Red Hat ranks #1 in value among software vendors. http://www.redhat.com/promo/vendor/
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