About `"Transfer-Encoding": "chunked"` and streaming response about jester HOT 5 CLOSED

What's the use case? :)

On Friday, 20 May 2016, wt [email protected] wrote:

@dom96 https://github.com/dom96

How about adding a sugar to write streaming response with "Transfer-Encoding":
"chunked" ?

import strutils, math
proc sendChunk_(response: jester.Response, data: string): Future[void] =
let dataLen = len(data)
let sizeLen = Positive(floor(log2(toFloat(dataLen)) / 4 + 1))
response.send(toHex(BiggestInt(dataLen), sizeLen) & "\r\n" & data & "\r\n")
proc endChunk_(response: jester.Response): Future[void] =
response.send("0\r\n\r\n")

Test example:

routes:
get "/":
var headers = newStringTable({
"Content-Type": "text/plain",
"Transfer-Encoding": "chunked"
})
await response.sendHeaders(Http202, headers)
await sleepAsync(1000)

await response.sendChunk("hello")
await sleepAsync(1000)

await response.sendChunk(" world")
await sleepAsync(1000)

await response.sendChunk("AAAAAAAAAAAAAAAAAAAAA")
await sleepAsync(1000)

await response.endChunk()

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#68

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@dom96

I am doing a hadoop service based on cloud. When user request a map reduce from my service, I will exec a hadoop mapreduce. The mapreduce will be long time, I want to tell user the real-time percentage progress:

[====  30%               ]

Then I should send a streaming response to user to update the percentage progress. The code looks like this:

proc mapreduceCb(response: Response): proc(data: JsonNode): Future[bool] =
  proc cb(data: JsonNode): Future[bool] =
    var percent = data["current"] / data["total"]
    var body = %* { "state": 0, "data": percent }
    response.sendChunk($body)
  result = cb

routes:
  post "/hadoop/mapreduce":
    let headers = newStringTable({
      "Content-Type": "application/json",
      "Transfer-Encoding": "chunked"
    })
    await response.sendHeaders(Http202, headers)

    var cluster = newHadoopCluster(...)
    var execs = await cluster.exec(..., mapreduceCb(response)) # mapreduce
    await response.endChunk()

from jester.

Just see ajax and web server, we can report real-time messages from the backend.

from jester.

I think I would prefer for this to be provided via an external library. You can easily create a jester_streaming package or similar.

from jester.

@dom96

Sure, that's also a good way.

This issure can be closed.

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