Hey! We’re going to have a lot of iot devices that need to connect to a server on our backend and we’re considering building our server with ktor, any thoughts on this? Is ktor a good idea to handle a lot of connections with small payloads?

Does someone use Ktor with the Dropbox API? There seems to be a bug that Dropbox can't be used while Google is fine. https://youtrack.jetbrains.com/issue/KTOR-3332

Any chance we might get to migration guide before docs are ready? 😉 I need to use 2.0.0 already because of Apple Silicon support, but I am having issues with figuring out how to migrate JSON serialization.

I'm assuming you had to write native HOCON parsing for the native client in 2.0, will that be added to the kotlinx.serialization hocon format?

Hi there! Does anybody know if

ktor 2.0

going to have support for multiplatform websockets (Client side)?

Haven't watched the ktor 2.0 video yet - is there any mention of gRPC support?

Honest question: What is it that excites people about the prospect of Ktor/Native for Server? I see quite a lot of enthusiasm for that but the reason is passing me by... ...aren't server side performance and runtime characteristics already well served on the JVM? While Native code can always surpass VM _in theory_; my understanding is the current Kotlin/Native compiler still has a long way to go before it can match the formidable optimisations implemented in, say, the Hotspot VM... and there's no assurance that JVM-beating performance will ever be a direct K/N goal. Only other factors I can think of are memory usage (JVM containers are typically memory hogs) or ease of deployment.

Hi how can we setup tcp keepalive for WebSocket Server on ktor?

The recording of What’s New in Ktor 2.0 is now available

Is Ktor native server already available via EAP?

Hi all, I’m posting here for some feedback and review. Me and my team were working on a library for making long-running task executions on top of Ktor webapp. Here’s the result, I’m adding few more details in the thread, I’d be glad if anyone could provide some feedback. Thank you!

Hi All! I’m very new to Kotlin and I’m trying to write a server, which retrieves some data from database every 15 seconds and sends it to connected clients via websockets. Websocket server is running as

embeddedServer

in my main function. I guess I have to use a coroutine for regular database queries, but how do I then pass results to websocket connections?

On writing UI with ktor, I started by using the html DSL and liked it, but ended up serving HTML files instead because it was taking too long to iterate on the UI. Is auto reload taking less than 2 seconds for you?

This message was deleted.

How coroutines work in ktor? I was checking out the samples and in the async sample I found that suspend functions are being called without any coroutine scopes.

get("/{...}") {
            val startTime = System.currentTimeMillis()
            
            // this is a suspend function
            call.respondHandlingLongCalculation(random, delayProvider, startTime)
        }

In this code,

call.respondHandlingLongCalculation(...)

is a suspend function and it is called without using any

launch

block. It seems that there is always a coroutine scope lying around in the ktor application. Q1. How can I use coroutines in a ktor application? If there is an implicit scope then what are the best practices to use it? Is there any guidelines? Q2. The scope of this question is little bit broad. How exactly a ktor server handle client connections? Does it launch a whole new instance of the application in a coroutine and it lives until the connection is closed? If not then how it manages concurrent connections? Let's say user A and user B connected to the server simultaneously. Though servers should be as stateless as possible but suppose I made a list of something for serving user A. Something like that,

// this is a global variable
var list: List<Int>? = null

fun ... (){
    get("..."){
        call.respond(list)
    }
}

Is there any chance that user A's data can also get served to user B if they hit the same endpoint?

Hi everyone, right now i'm building a ktor server to handle some web-request. In addition to that i would like talk to some other services via grpc. For example a flow like this: • Some other service initiates the flow via gRPC • Receive some data via Post-Method in ktor • Tell someone via gRPC that i got some data. I tried to just start a second server from the main-method for the gRPC handling, also after some testing i think it could work, but it feels a little wierd. Is there a proper way to do something like that?

fun main() {
    val server = GrpcServer(50051)
    server.start()
    // server.blockUntilShutdown()

    embeddedServer(Netty, port = 8080, host = "0.0.0.0") {
        installPlugins()
        configureModules()
    }.start(wait = true)
}

call.receiveOrNull<T>()

isn't working as expected. This is how you can reproduce, 1. Install the

ContentNegotiation

plugin for automatic deserialization of

json

content. (I am using

kotlinx.serialization

) 2. Define a model for the expected data 3. Send request with missing json field 4. Instead of returning null, it's throwing the exception and causing a

500 internal server error

Code,

fun Application.module() {
    install(ContentNegotiation) {
        json(
            Json { ignoreUnknownKeys = true }
        )
    }

    routing {
        post("/") {
            val user = call.receiveOrNull<User>()
                ?: return@post call.respondText(
                    text = "invalid request",
                    status = HttpStatusCode.BadRequest
                )
            call.respondText(text = "valid request", status = HttpStatusCode.Accepted)
        }
    }
}

Model,

@Serializable
data class User(
    @SerialName("username")
    val userName: String,
    val password: String
)

Sent request,

POST / HTTP/1.1
Accept: application/json, */*;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Content-Length: 24
Content-Type: application/json
Host: localhost:8080
User-Agent: HTTPie/2.5.0

{
    "username": "nilanjan"
}

Received response,

HTTP/1.1 500 Internal Server Error
Connection: keep-alive
Content-Length: 0

Exception thrown in the server,

kotlinx.serialization.MissingFieldException: Field 'password' is required for type with serial name 'com.jetbrains.handson.httpapi.User'

As a workaround I had to define my own

receiveOrNull

extension function.

suspend inline fun <reified T : Any> ApplicationCall.receiveOrNull(): T? {
    return try {
        receive<T>()
    } catch (cause: Exception) {
        null
    }
}

The actual

receiveOrNull

function in the

io.ktor.request

package looks like that,

public suspend fun <T : Any> ApplicationCall.receiveOrNull(type: KType): T? {
    return try {
        receive<T>(type)
    } catch (cause: ContentTransformationException) {
        application.log.debug("Conversion failed, null returned", cause)
        null
    }
}

Apparently, it's only catching the

ContentTransformationException

nothing else. This issue in YourTrack is similar to my issue, https://youtrack.jetbrains.com/issue/KTOR-545 So, my questions are, 1. Is this how the

receiveOrNull

function supposed to work? Or it is a bug? Do I have to report it? 2. If it's not a bug then why it is designed this way? Isn't it a good design to catch all kind of errors related to deserialization in the

receiveOrNull

function rather than causing an internal server error?

Hi all, has anybody of you experience with testing multipart uploads using the client's

MockEngine

? I want to test my client which is building a

MultiPartFormDataContent

using the

formData

builder (which by the way seems to lack support for appending files?). Now my problem is that the request body in the

MockEngine

is just a

MultiPartFormDataContent

only exposing properties of

OutgoingContent.WriteChannelContent

, which means I can only get the full body with all boundary strings and headers written in it. My current workaround is to more or less split the full body into somehow manageable parts, sadly all methods I could find for parsing

multipart/form-data

in ktor are either

internal

already or marked as deprecated as they will become

internal

in the future. Am I overlooking something or is ktor's api just lacking in this area as of now?

Been playing around with ktor 2, would still love to see

Url

marked as

@Serializable

OOTB (where it’s representation would be the url string). On a different note, thinking of

Url

as a (kotlinx) package might be neat too, so the ecosystem can center around a multiplatform type rather than existing platform-specific implementations

Being able to run a Ktor Server Instance embedded is absolutely delightful for writing integration tests betwen Client and Server. I can write tests that perform entire end-to-end User Registration/Activation/Login/Operation/Logout workflows. In the past developing such features has meant a lot of tedious environment wrangling as I build the server and client parts separately. Now the feedback loop is so tight, it's so much more enjoyable. Big love Ktor ❤️

Is there a way to find the git commit matching an eap release like

2.0.0-eap-259

?

When we want to use Ktor Client to access endpoints with or without authentication; is it expected we'll keep both 'authenticated' and 'unauthenticated'

HttpClient

instances on hand, and pick one? Or, is there a lighter way to opt to use the installed authentication, or not, per call?

Hi everyone! I'm trying to understand how to receive a JSON response without parsing it a Kotlin object (e.g. I need a pure JSONObject) However all I can find is about serialization and de-serializazion to objects. Any link on documentation that describes how to do what I need?

I got this fixed issue again in Ktor 1.6.3/4 https://youtrack.jetbrains.com/issue/KTOR-449 I added a comment in the fixed issue or should I instead create a new issue?

Hi all, Ktor looks awesome and we’re planning to try it out with an API endpoint. We have an existing spring app which has a service class with methods that we want to call from Ktor. How should be go about it? RPC? If so what tools do you recommend?

Anyone know of a good template / example of using ktor to serve a (separate) webpack typescript client project? Serving the compiled assets in production and using webpack dev server for development

Hi I am facing one issue with Ktor Auth module. I have a kmm project in which i have been using ktor for the api calls. I have a requirement in which i need to update my access token with the help of refresh tokens if they are expired. Basically i just need to add an authentication module in my ktor client. No I have gone through all the documentation of Ktor (https://ktor.io/docs/auth.html#configure_authentication) and added

Auth

module in my kmm. Now when i add auth module in my http client it gets added successfully and whenever i receive UnAuthorized user error from any api it calls my refresh token api. The issue is even though it calls my refresh token api but on success of refresh token it does not call the other api from which I have received UnAuthorized user error. It works as expected in android but the only issue is in ios client. Expected (Works fine in Android Http client) :- - Call any api -> if received any UnAuthorized user error call refresh token api -> onSuccess of refresh token api -> Call the first api again with the updated refresh token. Issue i am facing :- - Call any api -> if received any UnAuthorized user error call refresh token api -> onSuccess of refresh token api -> Does nothing on this step just throws unauthorized user error from the first api. HttpClient for iOS :-

actual class HttpBaseClient {

actual val tokenClient = HttpClient {

defaultRequest {

host = ApiEndPoints.Base.url

url {

protocol = URLProtocol.HTTPS

}

contentType(ContentType.Application.Json)

header(CONNECTION, CLOSE)

}

install(JsonFeature) {

val json = kotlinx.serialization.json.Json {

ignoreUnknownKeys = true

coerceInputValues = true

}

serializer = KotlinxSerializer(json)

}

}

actual val httpClient: HttpClient = HttpClient {

defaultRequest {

host = ApiEndPoints.Base.url

url {

protocol = URLProtocol.HTTPS

}

contentType(ContentType.Application.Json)

header(CONNECTION, CLOSE)

}

// Validate Response

expectSuccess = false

// Install Auth

install(Auth) {

lateinit var refreshTokenInfo : LoginResponse

bearer {

refreshTokens { unauthorizedResponse: HttpResponse ->

NSLog("Unauthorized response received")

BaseAPIClass().refreshAuthToken().fold(

failed = {

// On Failed

NSLog("Token Failed"). // No Callback received here

},

succeeded = { response ->

refreshTokenInfo = response

NSLog("Token Updated") // No Callback received here even when api is success

}

)

BearerTokens(

accessToken = refreshTokenInfo.accessToken ?: "",

refreshToken = refreshTokenInfo.refreshToken ?: ""

)

}

}

}

// JSON Deserializer

install(JsonFeature) {

val json = kotlinx.serialization.json.Json {

ignoreUnknownKeys = true

coerceInputValues = true

}

serializer = KotlinxSerializer(json)

}

Android Client (Pretty much same):-

actual class HttpBaseClient {

actual val tokenClient = HttpClient {

defaultRequest {

host = ApiEndPoints.Base.url

url {

protocol = URLProtocol.HTTPS

}

contentType(ContentType.Application.Json)

header(CONNECTION, CLOSE)

}

install(JsonFeature) {

val json = kotlinx.serialization.json.Json {

ignoreUnknownKeys = true

coerceInputValues = true

}

serializer = KotlinxSerializer(json)

}

install(Logging) {

logger = Logger.DEFAULT

level = LogLevel.ALL

}

}

actual val httpClient: HttpClient = HttpClient {

defaultRequest {

host = ApiEndPoints.Base.url

url {

protocol = URLProtocol.HTTPS

}

contentType(ContentType.Application.Json)

header(CONNECTION, CLOSE)

}

// Validate Response

expectSuccess = false

//Authentication

install(Auth) {

lateinit var refreshTokenInfo : LoginResponse

bearer {

refreshTokens { unauthorizedResponse: HttpResponse ->

BaseAPIClass().refreshAuthToken().fold(

failed = {

// On Failed

},

succeeded = { response ->

refreshTokenInfo = response

}

)

BearerTokens(

accessToken = refreshTokenInfo.accessToken ?: "",

refreshToken = refreshTokenInfo.refreshToken ?: ""

)

}

}

}

Ktor version :- 1.6.2 (tried 1.6.4 as well after reading this :- https://youtrack.jetbrains.com/issue/KTOR-491 but didn't work)

Hi all. I’m looking for recommendations on how long to keep a Ktor

HttpClient

alive. I’m using the Ktor client inside a REST service, and that client will be used to call out to other services. A few options for lifetimes might include: • Create one Ktor client instance for the lifetime of the service instance. All outbound requests will be made through that one client instance (across all inbound request threads) until the service instance is shut down, at which point we would call

close()

on the Ktor client. • Create one Ktor client instance for the lifetime of the inbound HTTP request. In this case, I’d call

close()

after we’re done processing the inbound request. • Create one Ktor client instance for each outbound HTTP request that we need to make. In this case, we’d call

use { }

in order to make sure the instance was properly closed once the outbound request has been completed. What do you recommend, and why do you recommend it? Thanks!

Is there a simple way to create an HttpClient using TestApplicationEngine without the withTestApplication around each test? I just want to create the client once on test initialization and use it without withTestApplication and handleRequest...