This is an Objective-C version of the reference ZeroMQ [object-oriented C API][zmq-docs]. It follows the guidelines laid out by the official ["Guidelines for ZeroMQ bindings"][binding-zmq].
[zmq-docs]: http://api.zeromq.org/zmq.html (zmq(7) Manual Page) [binding-zmq]: http://www.zeromq.org/docs:bindings (Guidelines for ZeroMQ Bindings)
Refer to the [ZeroMQ manual pages][zmq-docs].
The Objective-C binding
maintains a bit more state
than the C API exposes,
in that you can query
a ZMQContext
for its sockets
and query a ZMQSocket
for its context.
Early versions of ZeroMQ had some restrictive thread safety and coupling issues:
- Sockets can only be used from the thread that created them.
- All ZMQ sockets provided in a single call to
zmq_poll()must have been created using the same context.
Because sockets
are coupled to contexts
for polling,
you have to track
each socket's context
and make sure not to mix them.
(The ZMQSocket class tracks this for you.)
This is not as restrictive as it sounds,
because most applications will only ever use
a single context.
Prior to version 2.1.0,
each socket was permanently bound to the thread that created it.
This made it very difficult to use
ZeroMQ sockets
with Grand Central Dispatch
or NSOperationQueue, because
the only persistent thread
that these two APIs expose
is the thread
you're least likely
to want to perform socket operations on:
the main thread.
Starting with version 2.1.0,
a socket can be used from different threads
provided a full memory barrier,
such as that introduced by
<libkern/OSAtomic.h>'s
OSMemoryBarrier function,
separates the socket's use on one thread
from its use on another.
- Add functional tests in the form of sample code.
- Tie polling into the runloop, similar to
NSStream,CFSocket, orCFFileDescriptor.