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I want to use a node that both offers a service and subscribes to a topic. If, when ros::spin() is called I have both a new message in the topic and a request from the service, which callback function is called first? The service or the subscriber one?
I'd recommend reading the Callbacks and Spinning page page. Since it sounds like you are calling ros::spin(), then all callbacks get put into a callback queue in the order in which they are received. Then every call to ros::spin() will handle the callback at the front of the queue. So the answer to your question depends on the order in which the service request and the topic were received.
Asked: 2019-02-24 18:13:10 -0500
Seen: 763 times
Last updated: Mar 01 '19
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