These samples require an AMQP 1.0 broker or router to be running.
One option is http://qpid.apache.org/components/dispatch-router/index.html
It can be installed via dnf or apt, or from source: https://qpid.apache.org/packages.html
Run qdrouterd and the samples will work without any additional configuration.
The environment variable AMQP_URL can be set to indicate the location of the broker and the AMQP node address. It has this form:
amqp://user:pass@host:port/node
The default if AMQP_URL is not set is:
amqp://localhost:5672/test
Note: setting user:pass in a URL is not recommended in production,
it is done here to simplify using the samples.