Better Actions protocol implementation

[yznts]

Current approach is far from ideal. State and arguments are passed in SSE query, response must to be base64 encoded to avoid newlines issue (which increases the size of the response).

Websockets cannot be considered:

• They don't scale well (in case of keeping connection alive all the time)
• Sometimes it requires special configuration of networking, especially on big projects
• In some countries/hotels/public places you can see ports/protocols whitelisting, which immediately kills this approach

[yznts]

It's possible to use "chunked" transfer encoding to deliver multiple UI updates.

Example go server:

package main

import (
    "compress/gzip"
    "net/http"
    "time"
)

func main() {
    http.HandleFunc("/", func(rw http.ResponseWriter, r *http.Request) {
        rw.Header().Set("Content-Type", "application/octet-stream")
        rw.Header().Set("Content-Encoding", "gzip")
        rw.Header().Set("Transfer-Encoding", "chunked")
        rw.Header().Set("Access-Control-Allow-Origin", "*")

        writer := gzip.NewWriter(rw)

        writer.Write([]byte("Hello, World 1"))
        writer.Flush()
        rw.(http.Flusher).Flush()
        time.Sleep(time.Second)
        writer.Write([]byte("Hello, World 2"))
        writer.Flush()
        rw.(http.Flusher).Flush()
        time.Sleep(time.Second)
        writer.Write([]byte("Hello, World 3"))
        writer.Flush()
        rw.(http.Flusher).Flush()
        time.Sleep(time.Second)
        writer.Write([]byte("Hello, World 4"))
        writer.Flush()
        rw.(http.Flusher).Flush()
    })

    http.ListenAndServe("localhost:8080", nil)
}

Example JS client:

const response = await fetch('http://localhost:8080');
const reader = response.body.pipeThrough(new TextDecoderStream()).getReader();

while (true) {
    const { value, done } = await reader.read();
    if (done) {
        break
    }
    console.log(value)
}

console.log('end')

[yznts]

Marking as a good first issue. if someone is ready to take, just contact me directly for more information on that.

[yznts]

Better to do that without gzip encoding on handler side, leave it to middlewares.