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As of December 2013, this is an experimental project that does not implement yet the requirements below, but only provides a minimal feasability test, which demonstrates the feasability of CURVE proxying (cf § State below).
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For conveniance, I have copied a few include files from libzmq. The rational is to be able to work with this test as a standalone project, or integrated in libzmq/tests. These files are: include/zmq.h, include/zmq_utils.h, src/platform.hpp, and tests/testutil.hpp
StreamQ-Proxy aims at providing a proxy capable of proxying complex 0MQ security mechanisms. Today, if you want to setup a server secured with the CURVE mechanism as a broker and workers, all security handchecks and message en/decoding have to be performed inside the broker, then the messages are dispatched to the workers in plain text. We want the capability to delegate these towards the workers.
The use of ZMQ_STREAM socket type is the only identified solution to achieve this without modifying the ZMTP protocol that sustends libzmq.
So the architecture we want to implement is as follows:
___________________server__________________
____________proxy___________
Client ------- frontend / backend ------- Worker
DEALER ZMQ_STREAM ZMQ_STREAM DEALER
CURVE CURVE
Follow the link here
This is a starter project with a very minimal test program with only one client and one worker. So, I don't have to manage any pairing. It is implemented for CURVE, but any other mechanism shall be able to be used.
I have sticked to libzmq test_stream.cpp and zmq_proxy_steerable. The idea here is the proxy pools only workers at the beginning. When a worker connects, we pool also the client and the backend stays on standby until the client is identified. Then the proxy forwards all the messages from one to the other. There is a little state machine for the frontend and for the backend in the proxy.
This first feasability program works, including with multipart messages and asynchronous messages.
TODO: Extend to many clients & workers.
We have a simple bash builder for our first test program test_curve_proxying.
git clone https://github.com/lalebarde/streamq-proxy
cd streamq-proxy
./build-test_curve_proxying
Run with:
tests/test_curve_proxying
Concerning 0MQ:
Web site:http://www.zeromq.org/
Git repository: http://github.com/zeromq/libzmq
Development mailing list: zeromq-dev@lists.zeromq.org
Announcements mailing list: zeromq-announce@lists.zeromq.org
Concerning StreamQ-Proxy:
Git repository: http://github.com/lalebarde/streamq-proxy
Free use of this software is granted under the terms of the GNU Lesser General
Public License (LGPL). For details see the files COPYING and COPYING.LESSER
included with the StreamQ-Proxy distribution.