Kotlin examples and Kotlin support

[kenichi-fukushima]

Hello Armeria developers,

There are mentions of Kotlin examples here and there in Armeria documentation but I find none in https://github.com/line/armeria-examples. Is there any other place where I can find example code for common tasks in Armeria-Kotlin?

A particular task that I have is dispatching Kotlin coroutines from non-suspending Armeria methods such as AbstractHttpService.doGet() and SimpleDecoratingHttpService.serve()? I investigated how annotated services are couroutine-aware and found ArmeriaCoroutineUtil.callKotlinSuspendingMethod(). I might do the same thing in my code but a Kotlin beginner can't be confident that that's the right approach.

[jrhee17]

Sorry about the late response 😅

There are mentions of Kotlin examples here and there in Armeria documentation but I find none in https://github.com/line/armeria-examples. Is there any other place where I can find example code for common tasks in Armeria-Kotlin?

Hi, there has been a small issue with kotlin examples being exported to the armeria-examples repository. For now, kotlin related examples live in the main source.
I'll try to get the dead links fixed 😄 Thanks for the notice.

https://github.com/line/armeria/tree/main/examples

I investigated how annotated services are couroutine-aware and found ArmeriaCoroutineUtil.callKotlinSuspendingMethod(). I might do the same thing in my code but a Kotlin beginner can't be confident that that's the right approach.

Armeria internally already calls the method if the annotated service method is a suspending function, so it should work out of the box.

armeria/examples/annotated-http-service-kotlin/src/main/kotlin/example/armeria/server/annotated/kotlin/ContextAwareService.kt

Lines 16 to 30 in d9b6142

	suspend fun foo(@Param name: String, @Param id: Int): FooResponse {
	log.info("Hello $name")
	// Make sure that current thread is request context aware
	ServiceRequestContext.current()
	// Armeria request context will automatically be propagated to myDispatcher's scope.
	log.info("Start blocking task for $name")
	BusinessLogic.blockingTask()
	log.info("Finished blocking task for $name")
	// Make sure that current thread is request context aware
	ServiceRequestContext.current()
	return FooResponse(id = id, name = name)
	}

[fukushima-kenichi-mf]

Thanks for the reply. I will check those example in the main repo.

Armeria internally already calls the method if the annotated service method is a suspending function, so it should work out of the box.

I actually wanted know how I could generalize what AnnotatedService does to other Armeria APIs that are not coroutine aware.

[jrhee17]

I actually wanted know how I could generalize what AnnotatedService does to other Armeria APIs that are not coroutine aware.

I see, do you mind if I ask what armeria APIs you were looking to make coroutine aware?

[fukushima-kenichi-mf]

I see, do you mind if I ask what armeria APIs you were looking to make coroutine aware?

Generic AbstractHttpService and decorators.

[minwoox]

You might want to refer to this example:
#4725 (comment)
We've also added an extension method for context propagation which will be contained in the next release(1.26.0).

[fukushima-kenichi-mf]

Thanks! That seems like what exactly I was looking for.