Open the JavaScript console to watch log output.
Connect to your PostgreSQL database and publish an event:
SELECT pg_notify('crossbar_pubsub_event',
json_build_object(
'type', 'direct',
'topic', 'com.example.topic1',
'args', json_build_array(23, 7, 'hello world!'),
'kwargs', json_build_object('foo', 'bar', 'baz', 42)
)::text
);
You should see the event being received in JavaScript.