[zeromq-dev] PUB doesn't discard msg when no SUB

Chuck Remes cremes.devlist at mac.com
Thu May 26 21:27:18 CEST 2011

On May 26, 2011, at 2:18 PM, Martin Sustrik wrote:

> On 05/26/2011 08:49 PM, Pieter Hintjens wrote:
>> On Thu, May 26, 2011 at 11:41 AM, Li, Jia<jia.li at credit-suisse.com>  wrote:
>>> I see. How about adding a paragraph in the Guide to describe this behavior,
>>> just like it does warn about mixing socket types in devices? Since zmq is
>>> advertised as it-just-works, I was a little disappointed when it didn't and
>>> the user wasn't warned beforehand.
>> Indeed. I didn't even know it worked like this... :) My understanding
>> was that connect/bind were orthogonal to message flows but in fact it
>> seems that's not always the case. We learn something every day...
> Here's some background: The algorithm was implemented the "consistent" 
> way first. The connecting side dropped messages if the connection was 
> not established.
> This caused a lot of puzzlement among users. You would expect following 
> sequence of commands to actually send the message to the peer:
>     zmq_connect (s, "...");
>     zmq_send (s, msg);
> The problem is that connecting is asynchronous and takes certain amount 
> of time. Thus, when send is executed, the connection doesn't exist yet 
> and the message is dropped.
> So, what I did to make the behaviour more user friendly was to create a 
> "queue" as soon az zmq_connect() is called. It is then attached to the 
> actual network connection when it is established.

Please don't change this behavior. 


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