[zeromq-dev] What exact networking problems ZMQ does solve?

Lindley French lindleyf at gmail.com
Tue Dec 10 19:51:25 CET 2013

Let's start with automatic reconnection.

Everything in networking is about layers. By the time you get to the TCP layer, there is a lot going on already under the hood. TCP is a great protocol, but it has some downsides. If you want to send discrete messages rather than continuous streams, you need to delimit them somehow, or use a new TCP connection for each message (inefficient). Not hard, but 0mq or any other messaging middleware takes care of it for you.

Now, let's say there's an error. Worst case, the peer becomes unreachable. There isn't a whole lot any layer can do about this, except MAYBE confirm which messages got through. (It isn't possible, in general, to confirm a message did NOT make it.) Lots of errors are less severe. TCP RESETs occur with discouraging frequency in congested conditions. A layer like 0mq can substantially simplify the task of recovering from these conditions.

Sent from my iPhone

> On Dec 10, 2013, at 1:00 PM, artemv zmq <artemv.zmq at gmail.com> wrote:
> Yes I read a guide. But I want to ask question and get answer from real ppl. based on real use cases. 
> Ok. Let me re-phrase a bit. 
> - how one can benefit from automatic reconnection?
> - how one can benefit from HWM and in-memory message queueing if he/she develops peer-to-peer transactional appl.?
> - if peer is not connected and we send message there, why it's good idea to keep message in memory? where it helps?
> -  can I use ZMQ if I want develop something akin to http server? if this server is down, then can I get exception that I can't send him a msg?
> BR
> -artemv
> 2013/12/10 Gregg Irwin <gregg at pointillistic.com>
>> az> Can you please itemize what exact networking issues ZMQ does solve?
>> az> I have count 1 -- reconnection. Ok. But can you please provide more?
>> Have you read the bullet points at http://zeromq.org/, or skimmed
>> http://zeromq.org/intro:read-the-manual or the preface in the guide
>> (http://zguide.zeromq.org/page:all)?
>> -- Gregg
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