9 ms·

Server push is quite useful for bidirectional streaming of data which is heavily used in gRPC to help reduce latency and shovel large amounts of data.

Guthur 6y ago
And the problem there is shoe horning RPC requirements into a hypermedia transport. I feel we've made a big mistake following Google's micro service requirements for what should be a ubiquitous hypermedia back bone. It's bewildering that so many smart people could end up conflating the two for our standard protocols.
ahupp 6y ago
I think this is different than server push like WebSockets; this is all about pushing down resources the server suspects you'll need.
- josephg 6y ago
  Websockets are different again from both server push and h2 streams. Server push was a feature added in http2 for populating the browser’s cache. Websockets are an http/1.1 extension for tcp-like bidirectional messaging. Server push, websockets, h2 steams and webtransport are all different things.
  - brabel 6y ago
    Don't forget Server Sent Events[1] as well, which is yet another different technology. [1] https://en.wikipedia.org/wiki/Server-sent_events https://en.wikipedia.org/wiki/Server-sent_events
    - techdragon 6y ago
      Yea but unlike http2 push, server sent events were actually useful! You could use it super easily and by holding open a connection and pushing down little json or XML payloads you could build all sorts of things easily in JavaScript. I even saw super basic chat functionally built using two Iframes a form in one and the chat log pushed back from the server as a stream of valid but open ended HTML abusing how lax the browser was about parsing missing certain closing tags at the time. SSE was and still is super easy to use and a very useful option if you can’t or don’t want to shift to web sockets.
      - earthboundkid 6y ago
        Most applications that use WebSockets should be using SSE instead, but WS has better mindshare, and SSE doesn't work in IE11.
        josephg 6y ago
        SSE can be polyfilled to work in IE11. It can be implemented on top of XHR from ie7 or so onwards. Some caching proxies struggle with it though, because they try to buffer an entire response before forwarding it. And it’s 1 way. For something like collaborative editing, crafting a POST request for every keystroke feels wasteful, though it works great in practice.
      - bonkabonka 6y ago
        I'd second that! I use the heck out of SSE to add update notifications to various of my apps because it's just so easy to do. Have it glued to a Redis stream (or pubsub channel) with https://github.com/bonkabonka/sseredis https://github.com/bonkabonka/sseredis (though that shim looks like it needs a bit of love and a better README.)
psanford 6y ago
gRPC does not use PUSH_PROMISE. It uses HTTP/2 streams, but those streams all get initiated by the client.
- pa7x1 6y ago
  This 100%. There is so much confusion between HTTP/2 Push and and HTTP/2 bidirectional streaming capabilities, I personally had to go back to the Spec. to understand the difference because a lot of material just mixes them together. They are not the same thing.

Guthur 6y ago

And the problem there is shoe horning RPC requirements into a hypermedia transport. I feel we've made a big mistake following Google's micro service requirements for what should be a ubiquitous hypermedia back bone. It's bewildering that so many smart people could end up conflating the two for our standard protocols.

ahupp 6y ago

I think this is different than server push like WebSockets; this is all about pushing down resources the server suspects you'll need.

josephg 6y ago
Websockets are different again from both server push and h2 streams. Server push was a feature added in http2 for populating the browser’s cache. Websockets are an http/1.1 extension for tcp-like bidirectional messaging. Server push, websockets, h2 steams and webtransport are all different things.
- brabel 6y ago
  Don't forget Server Sent Events[1] as well, which is yet another different technology. [1] https://en.wikipedia.org/wiki/Server-sent_events https://en.wikipedia.org/wiki/Server-sent_events
  - techdragon 6y ago
    Yea but unlike http2 push, server sent events were actually useful! You could use it super easily and by holding open a connection and pushing down little json or XML payloads you could build all sorts of things easily in JavaScript. I even saw super basic chat functionally built using two Iframes a form in one and the chat log pushed back from the server as a stream of valid but open ended HTML abusing how lax the browser was about parsing missing certain closing tags at the time. SSE was and still is super easy to use and a very useful option if you can’t or don’t want to shift to web sockets.
    - earthboundkid 6y ago
      Most applications that use WebSockets should be using SSE instead, but WS has better mindshare, and SSE doesn't work in IE11.
      - josephg 6y ago
        SSE can be polyfilled to work in IE11. It can be implemented on top of XHR from ie7 or so onwards. Some caching proxies struggle with it though, because they try to buffer an entire response before forwarding it. And it’s 1 way. For something like collaborative editing, crafting a POST request for every keystroke feels wasteful, though it works great in practice.
    - bonkabonka 6y ago
      I'd second that! I use the heck out of SSE to add update notifications to various of my apps because it's just so easy to do. Have it glued to a Redis stream (or pubsub channel) with https://github.com/bonkabonka/sseredis https://github.com/bonkabonka/sseredis (though that shim looks like it needs a bit of love and a better README.)

psanford 6y ago

gRPC does not use PUSH_PROMISE. It uses HTTP/2 streams, but those streams all get initiated by the client.

pa7x1 6y ago
This 100%. There is so much confusion between HTTP/2 Push and and HTTP/2 bidirectional streaming capabilities, I personally had to go back to the Spec. to understand the difference because a lot of material just mixes them together. They are not the same thing.