[zeromq-dev] Core componets / files of the library

[Pieter Hintjens]

On Thu, Jun 20, 2013 at 5:24 PM, Martin Sustrik <sustrik at 250bpm.com> wrote:

> You can find a high level overview here:
> http://www.aosabook.org/en/zeromq.html
>
> I've also written a bit more concrete document here:
> http://www.zeromq.org/whitepapers:architecture

These are both excellent resources. Here's my minimal explanation:

libzmq is itself built using a messaging architecture:

* a bunch of objects (object.cpp)
* a dispatcher (io_thread.cpp)
* a set of messages, "commands"

Each object runs asynchronously on a single core and sends and
receives commands.

Objects are subclassed into (principally) sockets and sessions.

Applications talk to sockets which inject commands into the engine.

Sessions run in the background. They may use stream engines, and these
are tightly bound, not objects. So session and stream engine always
run in the same thread.

Sockets and sessions can have "pipes", which are message queues. There
are pipe pairs (one in each direction) and single pipes. Pipes are how
we implement outgoing and incoming message queues. Pipes can be
bounded (high-water marks).

So e.g. an inproc connection consists of two sockets, connected with
two pipes, one in each direction.

-Pieter