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Hello, Thanks for replies.

I know that publisher/subscriber could work with multiple publishers and multiple subscribers on a single topic. No problem for that.

It seems that my question was imprecise: let me try to explain.

I have a computer A with a publisher and another one B with a subscriber, talking using TCPROS (topic).

When a subscriber read a message from the topic, is-it needed for the computer PC B to read the message on computer A and to get it through the network or is the message already sent when the publisher published it and stored B ?

To explain my problem: the latency of my network is 50ms +/- 20ms (answer of ping command): in worst case, the latency will be 70ms for network. The rate of my publisher is 10Hz (100ms). So if computer A sends the message to queue in computer B as soon as the value is available, the subscriber can read the value after a maximum of 70 ms (on a computer the time to read the queue is negligible). In the other case, if computer B reads the value in queue on computer A, the worst case will be 170 ms after the value was read (worse case: the value was published 99.9ms be'fore + delay of network). It's a huge difference.

Hope someone can help me.

Merry Christmas to everyone !

Goupil