PubNub makes transport a non-issue by utilizing the most efficient/versatile protocol available for any given programming environment (via a client or server SDK) and providing access through a consistent and simple to use API. The SDKs are constantly updated to keep up with the latest emerging standards without exposing the intricacies of the protocol to developers.
This allows developers to spend their valuable time delivering app functionality with the peace of mind that the app's communication backbone is delivering the necessary performance and reliability. You can think of PubNub being a protocol itself which is scalable, secure and fast.