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I was working with different patterns in zeromq in my project and right now i am using req/rep(later will shift to dealer/router) and pub/sub . The client sends messages to the server and the server publishes this information to other clients who have subscribed.

To use multiple sockets i followed the suggestions on this thread Combining pub/sub with req/rep in zeromq and used zmq_poll . My server polls on req socket and pub socket.

While writing the code and while reading the above post i guessed that my pub socket will never get polledin and that's what i am observing now when i run the program. Only my request is polled in and publish is not happening at all. If i don't use polling it works fine i.e as soon as the server gets the message i publish it. So i am unclear on how polling will be useful in this pattern and how i can use it ?

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user1715513
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1 Answers1

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You probably don't need to poll the pub socket. You certainly don't need to poll in on it - because that can never be triggered (pub sockets are send only).

The polling pattern might be useful in the case where you want to poll for "ready to send" on the req and the pub socket, allowing you to multiplex those channels. This will be particularly useful if/when you move to using a dealer/router.

The reason for that is that replacing req with a dealer (e.g.) can allow you to send multiple messages before receiving responses. Polling for inward and outbound messages will allow you to make maximum advantage of that.

SteveLove
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