HTTP2 Support in Loopback

[shubhamp-sf]

Discussion space for HTTP2 support and to share insights for ideas on how it can be plugged into loopback.

Edit: SourceLoop team was able to make it work with Spdy
Checkout this blog here: https://blog.shubhamp.dev/how-to-use-http2-in-loopback-4-applications

[shubhamp-sf]

Initial Insights:

• Express is not compatible with http2 because it manipulates internals of the built-in request/response objects in an unsupported way.
• Loopback uses express internally mainly for middleware stuff, and calling them the way they were defined.

Related: #4989, #2078

[shubhamp-sf]

http2 takes 20% more memory than http1. (from: https://youtu.be/BF7uv5fs440?t=750)

[shubhamp-sf]

Compatibility

nodejs	express	spdy	http1.1	http2
17.3.1	4.17.1	4.0.2	✔️	❌
17.0.0	4.17.1	4.0.2	✔️	❌
16.13.1	4.17.1	4.0.2	✔️	❌
16.0.0	4.17.1	4.0.2	✔️	❌
15.14.0	4.17.1	4.0.2	✔️	❌
15.0.0	4.17.1	4.0.2	✔️	❌
14.18.2	4.17.1	4.0.2	✔️	✔️
14.0.0	4.17.1	4.0.2	✔️	✔️

Source: spdy-http2/node-spdy#380 (comment)

[shubhamp-sf]

HTTP/2 drops support of status messages. Eg. OK for 200.
This isn't used much but any client side code dependent on these status messages to proceed will break.

It's better to pass single-line summary of a response in body or custom headers.

[shubhamp-sf]

HTTP2 Spec: https://httpwg.org/specs/rfc7540.html

[shubhamp-sf]

A guide how to translate http/2 ⇆ http/1: https://httptoolkit.com/blog/translating-http-2-into-http-1/

Great insights from this thread from the author too: https://twitter.com/pimterry/status/1280132796951007233

[shubhamp-sf]

We were able to achieve it using Spdy
Checkout this blog here: https://blog.shubhamp.dev/how-to-use-http2-in-loopback-4-applications