On Wed, 2015-06-10 at 16:32 +0100, Gordon Sim wrote: > On 06/10/2015 04:01 PM, aconway wrote: > > On Tue, 2015-06-09 at 19:54 +0100, Gordon Sim wrote: > > > On 06/09/2015 06:40 PM, logty wrote: > > > > When I run the client I get: > > > > > > > > [0x5351db0]:0 <- @transfer(20) [handle=0, delivery-id=0, > > > > delivery > > > > -tag=b"", > > > > message-format=0, settled=true, more=true] (16363) > > > > "\x00Sp\xc0\x07\x05B..." > > > > > > My guess would be that it is the delivery tag being null (or > > > empty, > > > can't tell which) that is the problem. From the spec: > > > > > > "This field MUST be specified for the first transfer of > > > a multi-transfer message and can only be omitted for > > > continuation transfers." [section 2.7.5] > > > > > > So I think that whatever is sending that frame has a bug. Proton > > > -c > > > has a > > > bug too of course, since it shouldn't segfault but should close > > > the > > > connection with a framing-error or similar. > > > > It says the field must be specified, it does not say it must not be > > an > > empty binary value. Is the field really missing or is proton > > choking on > > a 0-length delivery tag? > > I'm not sure the distinction between null and an empty value is very > useful here. The intent is that the delivery is clearly identified. I > > would argue that a 'zero byte identifier' doesn't meet the spirit of > the > law there.
I disagree. An empty string is a perfectly legal value for a string. If the spec wants to assign special meaning to particular values of a property that needs to be stated. Of course, like you, I personally would not use an empty string as an identifier but as an implementor of an inter-operable spec I think we have to take the large view: *any* legal value of a parameter has to be considered equal unless the spec clearly states otherwise. > > It shouldn't, which might explain why rabbit is OK with > > it. > > I don't think RabbitMQ is ever seeing that frame. I believe that > frame > is emitted by ApolloMQ to the receiving client. Rabbit, Apollo, whoever. If somebody is using the empty string as a delivery tag and the spec does not clearly state "you must never use the empty string as a delivery tag" then we should accept it. > I agree that proton should not choke on a zero byte delivery tag (or > indeed on a non-existent delivery tag). But I do think it's a bug to > send such a frame. Quote me the spec, this is a mater of law not opinion ;)
