Hello guys,
Issue created: https://issues.apache.org/jira/browse/PROTON-1201
Regards,Adel
> Date: Tue, 17 May 2016 12:00:07 +0200
> Subject: Re: Proton C++ question
> From: rabih.prom...@gmail.com
> To: users@qpid.apache.org
>
> Thank you Gordon for your reply.
>
> I tried to add the link.close() in addition to connection.close() but the
> problem remains.
>
> The workaround with the credit window works.
>
> May be I should create a Jira issue for the bug.
>
> Thanks,
> Rabih
>
> On Tue, May 17, 2016 at 10:59 AM, Gordon Sim <g...@redhat.com> wrote:
>
> > On 10/05/16 11:38, Rabih M wrote:
> >
> >> Hello,
> >>
> >>
> >>
> >> I have an issue while using proton C++ binding 0.12.0. In my use case, I
> >> need to get one and only one message from a distant queue.
> >>
> >> But I am not able to do it with proton. I read that in the constructor of
> >> handler I could specify that using prefetch parameter, but it is not
> >> working.
> >>
> >
> > I'm not an expert on the c++ binding, but the prefetch is a window that is
> > automatically moved. So even if the window is only 1 message wide, once
> > that message is handled the library will automatically issue credit to move
> > the window forward.
> >
> >
> > That said, it is reasonable to expect that closing the connection as you
> > do on receiving the first message would prevent credit being reissued. Have
> > you tried closing the link as well? Does that make a difference? If not I'd
> > suggest this is a bug (the library should not issue extra credit on a link
> > that the application has requested be closed).
> >
> > As a workaround, you should be able to disable the credit window be
> > setting it to 0, then use the receiver::flow() method to add a single
> > message credit.
> >
> > Btw, I believe this has changed on the master (and therefore will be
> > different in the next release). It seems the prefetch is now called
> > credit_window, and is set through the link_options when creating the
> > receiver. Also the flow() method is now add_credit.
> >
> > Again, I repeat I am not an expert on the c++ binding, so apologies if any
> > of the above is incorrect. Hopefully one of the experts will then step in
> > and correct me :-)
> >
> > Example:
> >>
> >> Let’s consider I have a queue on the network that contains 2 messages.
> >>
> >> Here is my handler’s implementation:
> >>
> >> class SimpleReceiver : public proton::handler {
> >>
> >> private:
> >>
> >> proton::url url;
> >>
> >>
> >>
> >> public:
> >>
> >> SimpleReceiver(const proton::url& u) : *handler(1)*, url(u) {}
> >>
> >>
> >>
> >> void on_start(proton::event &e) {
> >>
> >> proton::connection conn = e.container().connect(url);
> >>
> >> conn.open_receiver(url.path());
> >>
> >> }
> >>
> >>
> >>
> >> void on_message(proton::event &e) {
> >>
> >> std::cout << e.message().body() << std::endl;
> >>
> >> e.connection().close();
> >>
> >> }
> >>
> >> };
> >>
> >>
> >>
> >> When I run this code the queue is emptied and the client took the 2
> >> messages from the queue.
> >>
> >>
> >>
> >> Could you help me understand why I am getting this behavior?
> >>
> >>
> >>
> >> Thank you,
> >>
> >> Rabih
> >>
> >>
> >
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> >
