I'm having apparently a problem with ContentNegoti...

# ktor

[Stephan Schröder]

I'm having apparently a problem with ContentNegotiation in a Ktor 3.1.1, Kotlin 2.1.10 project. So this works:

get("/stream/{n}") {
            call.respondBytes(
                contentType = null,
                status = HttpStatusCode.OK,
            ) {
                ByteArrayOutputStream(64).apply {
                    repeat(3) {
                        write("Hello Bytes!".toByteArray())
                    }
                }.toByteArray()
            }
        }

it outputs:

curl -X GET "<http://localhost:8081/stream/1>"
Hello Bytes!Hello Bytes!Hello Bytes!

but using respondBytesWrite

get("/stream/{n}") {
            call.respondBytesWriter(
                contentType = null,
                status = HttpStatusCode.OK
            ) {
                repeat(3) {
                    writeByteArray("Hello Bytes!".toByteArray())
                }
            }
        }

leads to an empty response:

curl -X GET "<http://localhost:8081/stream/1>"
curl: (52) Empty reply from serve

but when I comment out the ContentNegotiation dependencies ktor-server-content-negotiation-jvm and ktor-serialization-kotlinx-json-jvm , it works again 🤷‍♂️
My ContentNegotiation config is pretty bare metal:

fun Application.configureSerialization() {
    install(ContentNegotiation) {
        json()
    }
}

What am I missing?

[Aleksei Tirman [JB]]

Do you use the Maven build system?

[Stephan Schröder]

yes, i do.

[madisp]

if you hint the content-length and content-type, does it work?

[madisp]

e.g. application/octet-stream and 36 in this case (3x "Hello Bytes!" length)

[Aleksei Tirman [JB]]

Most likely, this is KTOR-7662. Can you try to explicitly define the kotlinx-io-core-jvm dependency as described in the comment?

[Stephan Schröder]

@madisp just setting the content-length is enough! 🤯 (the content-type makes no difference). but I don't know the content-length at this point, I build it up dynamically and first writing everything to a buffer defeats the purpose of using a write (less copying) 😮

[madisp]

give Aleksei's kotlinx-io-core-jvm dependency a try, sounds like a bug with chunked transfer encoding due to that

[madisp]

if possible, I recommend trying to figure out the content length though, chunked transfer encoding is a pain in general

[Stephan Schröder]

will do. Paralell to me my collegue just replaced ktor-serialization-kotlinx-json-jvm with ktor-serialization-jackson-jvm and that fixes it as well.

[Stephan Schröder]

yes, the kotlinx-io-core-jvm dependency fixes it as well! Thanks 👍