Streaming JSON objects using akka http chunked response

Question

Is it abuse or somehow dangerous to use akka-http like this?

On server

def source(consumerOffset: UUID) = 
  readJournal.eventsByTag(“MyTag", consumerOffset).map(_.asJson)

pathPrefix("stream" / Segment.map(UUID.fromString)) { offset =>
  pathEndOrSingleSlash {
    get {
      complete {
        HttpResponse(
          StatusCodes.OK,
          entity = HttpEntity(ContentTypes.`application/json`, source(offset))
        )
      }
    }
  }
}

Then on client side

Source.single(HttpRequest("http://localhost:9000/stream"))
  .mapAsync(1) { r =>
    Http().singleRequest(r).map { res =>
      res.entity.dataBytes.map(_.parse[Event])
    }
  }
  .flatMapConcat(identity).mapAsync(processEvent)

UPD:

Is it guaranteed that chunks I send will be the same on client side.
Is it ok to have response with possibly endless number of chunks?
What is the right Content-Type for this kind of response?

UPD 2:

Akka 2.4.9 added ability to respond with streams. And basically does exactly the same, providing some syntax sugar. See the docs.

Which part are you concerned about? It all appears to be boiler plater at first glance... — Ramón J Romero y Vigil, Jul 05 '16 at 10:59
1. Is it guaranteed that chunks I send will be the same on client side. — Denis Mikhaylov, Jul 05 '16 at 11:30
2. Is it ok to have response with possibly endless number of chunks? — Denis Mikhaylov, Jul 05 '16 at 11:31
@DenisMikhaylov In addition to this, What happens if the Client closes the connection in b/w, but server has no possible way to know it, server thinks the client is just slow in consuming and it keeps buffering the response. How to handle these scenarios? — curious, Jun 26 '17 at 13:09
@curious There is an `idle connection timeout` setting for such scenarios — Denis Mikhaylov, Jun 26 '17 at 19:48

score 1 · Accepted Answer · answered Jul 05 '16 at 17:21

Answering your questions in order:

Yes, the client will receive BytesString representations of your objects encoded in json.
Yes, it is fine to have a stream source on the server side which never terminates.
The content you've specified in the question (application/json) is correct.

Streaming JSON objects using akka http chunked response

1 Answers1