Wildcard Subscribe introduces the ability to add namespaces to channels. Wildcarding is supported up to three levels deep. So you can subscribe to:
but you cannot subscribe to ‘*.’, ‘a.b.c.*’ nor just ‘*’.
For example, if you need to subscribe to every device in San Francisco or California, you can save yourself from providing a lengthy delimited list of every channel by instead subscribing to ‘california.*’ or ‘california.sanFrancisco.*’.
This feature must explicitly be turned on in your PubNub Admin Dashboard.
For further learning, please see: