I recently migrated my app server to ktor + websockets and now we observe those excepeptions in receive loop:

java.util.concurrent.CancellationException: LinkedListChannel was cancelled

(full traceback at https://pastebin.com/GU3a8HMD ) Loop looks like this:

try {
            for (frame in websocketSession.incoming) {
                frame as? Frame.Text ?: continue
                val content = frame.readText()

                ctx.sessionScope.launch {
                    handleMessage(ctx, content)
                }
            }
        } catch (e: ClosedReceiveChannelException) {
            // socket is closed from client and handled by ktor
        } catch (e: Throwable) {
            // error occured (abrupt connection termination or other websocket internal error)
            logger.error("Unhandled websocket session error: ${e.message}", e)
        }

Ktor 1.5.2, coroutines 1.4.2, netty 4.1.54.Final

Hi, is there any way to generate a client sdk from a ktor server automatically?

I'm not sure why but my

Long

is getting rounded when trying to deserialize it within Kotlin/JS, according to this https://github.com/Kotlin/kotlinx.serialization/blob/master/docs/builtin-classes.md it shouldn't happen... but it does?

Hi all! I have some issues with sealed classes and JSON. If I do not wrap a sealed class in a wrapper then the discriminator is not send out

Is there a way to retry requests with Ktor ? I’ve tried using HttpSend feature, but wasn’t able to get the request to retry 😞 I am referring to client implementation ofc

I have this code in my server Application module :

install(Sessions) {
    cookie<Session>("JSESSIONID", directorySessionStorage(File(".sessions"), cached = true)) {
        cookie.extensions["SameSite"] = "lax"
        cookie.path = "/"
    }
}

Let say the Session class is a general purpose empty class that I just want always created, independent of any authentication mechanism. What else do I need in my application routing for the Set-Cookies header to be generated in each response ?

Hello all 👋. I'm looking to hire some help in building a basic CRUD app using Ktor. I've tried myself, but found I got a long way to go with setting up Docker/Linux/MySql etc. Please DM if you're free for work. Thanks!

When serving static files using Ktor, how do you override what content type Ktor sets on the response?

QUESTION TIME Folks, I have a question regarding Ktor “Features”. In many technologies Features are called other things such as Middleware, Interceptors, Filters, etc. When you first came to Ktor, did you immediately understand what “Feature’ means? Do you at all find it complicated to talk about Features, not to be confused with features? 🙂

First timer with Ktor here. Ktor client is throwing

<http://io.ktor.utils.io|io.ktor.utils.io>.charsets.MalformedInputException: Input length = 1

when I try to receive

gzip

encoded response. Any idea how can I enable

gzip

decoding in

HttpClient

?

Is there a recommend method to unit test JSON in Kotlin? Like, asserting if one json string is equal to the other

Just got a wierd error:

```17:24:26.967 [DefaultDispatcher-worker-2 @request-handler#28] ERROR ktor.application - Unhandled: GET - /
java.lang.NullPointerException: jarEntry must not be null
	at io.ktor.http.content.JarFileContent.<init>(JarFileContent.kt:41)
	at io.ktor.http.content.StaticContentResolutionKt.resourceClasspathResource(StaticContentResolution.kt:62)
	at io.ktor.http.content.StaticContentResolutionKt.resolveResource(StaticContentResolution.kt:38)
	at io.ktor.http.content.StaticContentResolutionKt.resolveResource$default(StaticContentResolution.kt:24)
	at io.ktor.http.content.StaticContentKt$resources$1.invokeSuspend(StaticContent.kt:230)
	at io.ktor.http.content.StaticContentKt$resources$1.invoke(StaticContent.kt)
	at io.ktor.util.pipeline.SuspendFunctionGun.loop(SuspendFunctionGun.kt:246)
	at io.ktor.util.pipeline.SuspendFunctionGun.proceed(SuspendFunctionGun.kt:116)
	at io.ktor.util.pipeline.SuspendFunctionGun.execute(SuspendFunctionGun.kt:136)
	at io.ktor.util.pipeline.Pipeline.execute(Pipeline.kt:79)
	at io.ktor.routing.Routing.executeResult(Routing.kt:155)
	at io.ktor.routing.Routing.interceptor(Routing.kt:39)
	at io.ktor.routing.Routing$Feature$install$1.invokeSuspend(Routing.kt:107)
	at io.ktor.routing.Routing$Feature$install$1.invoke(Routing.kt)
	at io.ktor.util.pipeline.DebugPipelineContext.proceedLoop(DebugPipelineContext.kt:82)
	at io.ktor.util.pipeline.DebugPipelineContext.proceed(DebugPipelineContext.kt:60)
	at io.ktor.util.pipeline.DebugPipelineContext.execute(DebugPipelineContext.kt:66)
	at io.ktor.util.pipeline.Pipeline.execute(Pipeline.kt:79)
	at io.ktor.server.engine.DefaultEnginePipelineKt$defaultEnginePipeline$2.invokeSuspend(DefaultEnginePipeline.kt:124)
	at io.ktor.server.engine.DefaultEnginePipelineKt$defaultEnginePipeline$2.invoke(DefaultEnginePipeline.kt)
	at io.ktor.util.pipeline.DebugPipelineContext.proceedLoop(DebugPipelineContext.kt:82)
	at io.ktor.util.pipeline.DebugPipelineContext.proceed(DebugPipelineContext.kt:60)
	at io.ktor.util.pipeline.DebugPipelineContext.execute(DebugPipelineContext.kt:66)
	at io.ktor.util.pipeline.Pipeline.execute(Pipeline.kt:79)
	at io.ktor.server.cio.CIOApplicationEngine$handleRequest$2.invokeSuspend(CIOApplicationEngine.kt:189)
	at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
	at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:106)
	at kotlinx.coroutines.scheduling.CoroutineScheduler.runSafely(CoroutineScheduler.kt:571)
	at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.executeTask(CoroutineScheduler.kt:750)
	at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.runWorker(CoroutineScheduler.kt:678)
	at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.run(CoroutineScheduler.kt:665)

The error arises on liberica-15 (CIO) when useing

static{resources()}

and everything works fine on graalvm11. Does anybody have the same problem? The issue.

Hi guys, having troubles with call.parameter with "+" as a character. I have ContentNegotiation and DataConversion setted. Someone knows what can it be? Thanks.

How can I do a request like this using the ktor client?

curl --request POST --form "field=value" <http://localhost:8080>

I have tried looking at

submitForm

but when using this it just gives this error:

Serializer for class 'FormDataContent' is not found.

Which library do you recommend for DTO validations for ktor?

Hi ktor community. All the ktor tutorials on the kotlin site seem to have everything in one project. Is it possible to have separate projects and repositories for each part of a multiplatform app? E.g. 1 repo just for server, 1 for the shared logic, and 1 for each client that would have a dependency on the shared repo. It seems like it should be possible but I’m finding it very confusing to get running due to not finding any examples. E.g. where did the jvmJar build task come from in the sample app? Do we have to have one “god” repository or can we split it up? E.g. I only want to use android studio for the android client. I don’t want to see ios stuff in there. I want to build the shared code in intellij where it has nothing to do with android. and ios should be only in xcode with the shared framework as a dependency. Hope that makes sense. Not seeing anyone talking about doing it this way.

How can I get this DRY? Hello All, right now I learn a lot about Kotlin extension functions and Kotlin DSLs. When using the DSL for Ktor routes I came to a point where I don't know how to get my routes setup DRY. In the example below, is there any chance to avoid repeating the routes

underpants()

and

groot()

?

class SomeApp {

    fun Application.main(testing: Boolean = false) {

        when {
            isDev -> {
                // For dev environment only
                routing {
                    groot()                    
                    underpants()
                }
            }
            isProd -> {
                // Do things only in prod
                routing {
                    authenticate {
                        groot()                    
                        underpants()                    
                    }
                }
            }
        }

        // Do things for all the environments

        install(ContentNegotiation) {
            gson {
                setPrettyPrinting()
            }
        }
    }
} 

fun Route.groot(
) {
    get("/api/groot") {
        val map: HashMap<Int, String> = hashMapOf(1 to "I", 2 to "am", 3 to "groot!")
        call.respond(map)
    }
}

:
:

well another annoying question from me 🙂 (Thanks for being so patient with me) so I have an incoming multipart request, the multipart is a true multipart, so with both `PartData.FormItem`s and

PartData.FileItem

s 🙂 now the big bad boy, because the `FormItem`s are json that needs to mapped to the DTOs, normally I'd do

call.receive<FooDto>()

and then take it from there, but there's no apparent equivalent logic on the

FormItem

that I can find. What is the best approach for this, so I don't have to re-implement part/all of the receive logic?

Any Advice on that? Аt this moment I see only one way, is to define intercepter on okhttp level which is used as an engine for ktor on android side. And do it somehow similar on iOS. But this is not the way I’m looking for. Want to implement it once on multiplatform level. Does anyone solves this problem and could advice right direction to dig into?

Hi Guys, I've been trying to add in

IosClientEngine

inside my

iosMain

but I can't seem to find the builder function

Ios

. I've added the dependency:

val iosMain by getting {
    dependencies {
        implementation("io.ktor:ktor-client-ios:1.5.2")
    }
}

But I still couldn't access

Ios.create {  ... }

? I am able to see

internal IosClientEngine(...): ...

) but not the

Ios

client. Is there something specific that I should do? please help. Thanks in advance.

The Ktor client documentation only lists

basic

and

digest

, how can I use the other authentication methods? https://ktor.io/docs/features-auth.html#providers

Hi, I was trying to write a generic networking client using ktor.

override suspend fun <T : Any> getJsonFromRouter(router: APIRouter, success: Success<T>, failure: Failure) {
        try {
            val json = httpClient.get<String>(requestFromRouter(router))
            Json.decodeFromString(T.serializer(), json)
                .entries
                .also(success)
        } catch (ex: Exception) {
            Failure(error = ex)
        }
    }

I’m getting error on

T.serializer()

. Error = “Not enough information to infer type variable T”. On iOS we have Decodable which allows these kind of generic implementation. Was wondering if this is allowed on kotlin or this can’t be achieved and an actual type in place if generic T is required?

Trying to create a DateTime property for a model, i’m using exposed + Postgres, and

kotlinx.serialization

Apparently I can’t respond back the Data while using

datetime(“created_at”)

method in exposed! Any solution?

How to cancel requests in ktor client , multiplatform?

I am trying to download big file using Ktor and streaming feature, but I encountered issue. Code:

client.get<HttpStatement>(downloadUrl).execute {
                    var offset = 0
                    val byteBufferSize = 1024 * 100

                    val channel = it.receive<ByteReadChannel>()
                    val writeChannel = osmFile.writeChannel()
                    do {
                        val data = ByteArray(byteBufferSize)

                        val currentRead = channel.readAvailable(data, offset, byteBufferSize)

                        writeChannel.writeAvailable(data,offset,currentRead)


                        offset += currentRead

                        println("Pushed $offset bytes with current read $currentRead")
                    } while (currentRead >= 0)
                }

I see that it will download file only until byteBufferSize. I though it was limit for one package, but something in code is making this hard top limit. I though it would work like this: 1. set bufferSize limit for package 2. open write channel for file 3. create ByteArray to store bytes from one package 4. read from readChannel bytes, using current offset, and bufferSize limit, and write it to ByteArray 5. read from ByteArray and save those bytes into file Can someone explain me what I did wrong? Thanks! PS file is downloaded for 100 kb and it stops. If limit wouldn't be so perfect, it would crash with OutOfBounds exception

hi all, I’m facing a small problem with the ktor client proxy configuration. my current setup is, that I’m using the apache engine in my ktor client, as I need a connection with credentials. But I have also a different problem. how I can also route connection differently for some hosts? So host1 should use the proxy settings and host2 don’t. I hope I can get some guidance here.

Hey I have asked this before. Can someone tell me difference between

maxConnectionsCount

,

maxConnectionsPerRoute

,

pipelineMaxSize

in http client with CIO engine. Also what is the role of

threadsCount

with coroutines in CIO engine ? The kotlin doc inside :

maxConnectionsCount = Maximum allowed connections count.
maxConnectionsPerRoute = Maximum connections per single route.
pipelineMaxSize = Maximum number of requests per single pipeline.
threadsCount = Network threads count advice.

It is crisp, and I understand it, but I also assume here. I would like a better explanation. Please help 🙂

Keep getting these weird logs for ktor endpoint under basic auth. They always come in pairs and they actually go through fine (meaning the request if processed as normal and not rejected):

2021-03-24T17:42:21.770240342Z [INFO ] 17:42:21 [tDispatcher-worker-2] Application                    - 401 Unauthorized: POST - /api/libraries
2021-03-24T17:42:21.981263639Z [INFO ] 17:42:21 [tDispatcher-worker-3] Application                    - 201 Created: POST - /api/libraries

Has anyone experienced it themselves?

Hi - I'm new to ktor but have used coroutines in Android before. And I'm concerned I'm that I'm over engineering my code due to my lack of understanding of coroutines. My understanding of coroutines is as follows: • Coroutine jobs run on a context. • Each context is associated with a thread or pool of threads which can be allocated a priority. • Many jobs can efficiently run on the same context, even if there is actually only one thread, with jobs constantly being suspended and interleaved. • You are still limited to the hardware you are running on, so the only advantage of having multiple contexts are to manage priority and allow jobs to be stopped/tidied up if the process that spawned the job has stopped etc. In Android it's easy to understand that you need to get many long running processes off the main thread, and when we started doing that we noticed that the UI experience of the app was noticeable improved, smother scrolling etc. With my ktor application I'm not too sure what I'm doing. My understanding and looking at the source code suggests that when my

ApplicationCall

function is called I'm already on a coroutine context. My questions are: • Do I need to ever move away from the default context that ktor server call starts on? - I don't think I'm doing anything computationally expensive (I think), but I am wrapping some third party callbacks like firestore and calling a few third party api's which I'm using the ktor client for anyway. • Are there tools to monitor and discover what parts of the code I should be moving to a different, lower priority, context?

Is there a kotlin version requirement for ktor 1.5.2? Can a project be in kotlin 1.4.2 and use ktor 1.5.2 without any issues?