Hi Derek. Thank you for mentioning us here. The age-old conversation on transport protocols is evergreen. The goal of these protocols is to allow data transmission from one device, to other devices. It is great to be on the leading edge of technology, continuing the innovative optimizations of the use of the internet. As the internet scales, more devices need connectivity and each byte counts more and more. There are 20 billion connected internet devices today (2018). That's 2x more than the number of humans. The device to human ratio continues to grow. We need efficient and affective methods for coordinating information between devices.

The various methods to coordinate information between devices on the internet should be looked at objectively and mechanically. At the end of the day, the modern reliable messaging protocols use the IP Frames. The basis of our internet. Layer 6 protocols based on IP Frames are not equal. Many methods are not compatible with the various configurations of networks. The bytes and bandwidth required between each production-ready method differ.

* HTTP/1.1 - 100% Compatibility

* HTTP/2.0 - 100% Compatibility with client initiated connectivity and backward compatibility with HTTP/1

* MQTT - near-full internet wide compatibility ( routing policy / network topology )

* WS - near-full internet wide compatibility ( routing policy / network topology )

Each message received using these mechanisms requires TCP ACKs. The promise of MQTT and WS leads you to believe that the data streaming to your device over WS or MQTT don't require ACKs. However this is not how TCP works. When packets are received there is an associated timeout and retransmission when an ACK is late or missing. Additionally light-weight layer 6 traffic is required to maintain connectivity between two endpoints. Otherwise LRUs and quotas are triggered for routes could be treated as stale, and therefore dropped altogether. This is the underlying mechanism of the layer 6 protocols that are often left out of the discussions.

There is a clear winning approach in my mind. HTTP/2.0 includes, by default, server-initiated data push. The required TLS and header compression, as part of the spec, allow for a secure yet efficient streaming solution. With HTTP/2.0, TCP socket limits are less of a concern, as the client only needs one TCP socket to subscribe to an unlimited number of data feeds. HTTP/1 requires the client to maintain separate sockets for each independent stream, as HTTP/1 enforces head-of-line ordering for muxing. Something we've done special for HTTP/1 clients, we've added multiplexing by allowing multiple topic subscriptions and filter expressions to be passed in a single HTTP call on the same socket. This isn't natively built into HTTP/1 and is supported on all our SDKs.

This is why we have chosen HTTP/2.0 as our next-gen transport protocol. We have started by providing HTTP/2.0 connectivity at our edge for select customers. As of 2018 PubNub is the world-record holder for the largest online concurrent event in human history using HTTP/2.0 for live data streams on a globally celebrated sporting event.

You should be using HTTP/2.0 for your customers. Here is a dockerfile that makes it easy for you to start testing HTTP/2.0 - https://github.com/stephenlb/http2-proxy

Stephen Blum ( @stephenlb )
CTO PubNub