[zeromq-dev] Improving message patterns

[Martin Sustrik]

Brian, Paul,

>> One thing that would be nice, is to allow multiple zeromq socket to
>> run through a single TCP socket.  that would really help the growth of
>> TCP connections in these architectures.

You mean single port rather than single TCP connection, right? If so, I 
am fully agreed.

As for a single connection, the problem is that it would exhibit 
head-of-line blocking behaviour, i.e. if any of the contained channels 
would reach HWM on the receiver, the receiver application would have to 
stop reading data from network, which in turn would block all the 
channels on that connection, even those that haven't reached HWM.

> Well, this quite contradicts my point. I like to use different TCP ports
> even if zmq socket same. This helps monitor traffic better. And I've thought
> the only overhead of lots of TCP connections is connection initiation
> overhead, which zeromq doesn't do most of the time. What's your
> experience?

That was my opinion originally: Every feed should use different port so 
that underlying layers have access to the individual "business feeds" 
(monitoring, traffic shaping etc.)

However, in the modern world where ease of deployment beats good design 
any time, insisting on opening a port in firewall for every new business 
feed is almost a death sentence for the technology.

Btw, for those interested in this kind of stuff, I really enjoyed this 
draft that discusses the problem in detail:

http://tools.ietf.org/html/draft-tschofenig-post-standardization-00

Martin