ZeroMQ does not resend messages, so while the reconnect/queuing logic will protect you to some degree, you still need to account for message loss.
If you're using REQ then you'll need to timeout the request, otherwise if a request or response message is lost then you'll never be able to make a request on the socket ever again. So don't just indefinitely block on a send or receive. Further, ZeroMQ historically hasn't had a way to get a REQ socket out of the "waiting for response" state in the event of a timeout other than by closing the socket and starting over. This means the REQ type is not really usable in production. Better to use DEALER and format a REQ-compatible message yourself. REP does not suffer from these problems, so you can keep on using that and have DEALER talk to REP. Note: it is possible that very recent versions of ZeroMQ allow REQ sockets to revert state on error but I haven't been following this closely. On 12/13/2013 04:17 PM, Sean Robertson wrote: > I believe the REQ will simply wait for the REP to come back up, > re-bind and send something. > > On Fri, Dec 13, 2013 at 2:53 PM, Mohit Jaggi <[email protected]> wrote: >> Hi, >> In most ZMQ sockets, the underlying TCP socket can change transparently. >> Does that apply to REQ-REP sockets as well? Or will the receive call to ZMQ >> socket fail? >> >> sock = new REQ socket; >> connect(sock); >> while(1) { >> request = receive(...); >> ... >> send(response); >> } >> >> For example in the above code, let us say that the server with REP socket on >> the other side crashed and restarted. What will happen? >> >> Thanks, >> Mohit. >> >> _______________________________________________ >> zeromq-dev mailing list >> [email protected] >> http://lists.zeromq.org/mailman/listinfo/zeromq-dev >> > _______________________________________________ > zeromq-dev mailing list > [email protected] > http://lists.zeromq.org/mailman/listinfo/zeromq-dev > _______________________________________________ zeromq-dev mailing list [email protected] http://lists.zeromq.org/mailman/listinfo/zeromq-dev
