Upgrading from ZeroMQ v2.2 to ZeroMQ v3.2

Compatible Changes

These changes don't impact existing application code directly:

• Pub-sub filtering is now done at the publisher side instead of subscriber side. This improves performance significantly in many pub-sub use cases. You can mix v3.2 and v2.1/v2.2 publishers and subscribers safely.

• ZeroMQ v3.2 has many new API methods (zmq_disconnect(), zmq_unbind(), zmq_monitor(),zmq_ctx_set(), etc.)

Incompatible Changes

These are the main areas of impact on applications and language bindings:

• Changed send/recv methods: zmq_send() and zmq_recv() have a different, simpler interface, and the old functionality is now provided by zmq_msg_send() and zmq_msg_recv(). Symptom: compile errors. Solution: fix up your code.

• These two methods return positive values on success, and -1 on error. In v2.x they always returned zero on success. Symptom: apparent errors when things actually work fine. Solution: test strictly for return code = -1, not non-zero.

• zmq_poll() now waits for milliseconds, not microseconds. Symptom: application stops responding (in fact responds 1000 times slower). Solution: use the ZMQ_POLL_MSEC macro defined below, in all zmq_pollcalls.

• ZMQ_NOBLOCK is now called ZMQ_DONTWAIT. Symptom: compile failures on the ZMQ_NOBLOCK macro.

• The ZMQ_HWM socket option is now broken into ZMQ_SNDHWM and ZMQ_RCVHWM. Symptom: compile failures on the ZMQ_HWM macro.

• Most but not all zmq_getsockopt() options are now integer values. Symptom: runtime error returns onzmq_setsockopt and zmq_getsockopt.

• The ZMQ_SWAP option has been removed. Symptom: compile failures on ZMQ_SWAP. Solution: redesign any code that uses this functionality.