Hi folks. Apologies — I am not a Kotlin expert. I currently work at a co that has several Kotlin web services built on Dropwizard, JOOQ, Sqitch. They’ve served our org well and I’m planning on taking a similar direction for a new web service that needs to be built. I was wondering if anyone in this group has strong opinions on technology selections I might consider in the new service that could benefit our org overall in the long term (considering where we are at currently). I’m very unfamiliar with the landscape of options out there. I’m especially interested in any experience folks have with developing gRPC services or other approaches to automating server-endpoint and api-client construction in a Kotlin context.

Question about testing ktor. Has anyone had luck mocking an ApplicationRequest? I'd like to be able to write unit tests without the whole test server harness, which has been fine for integration testing but a bit much for unit tests. Specifically, I just want to test a function that parses a request, so I just want to pass my function a test request without having to make a call to the test server to get one

Hi folks, I've been building a simplicity-prioritized web application from the ground-up, with the fewest possible dependencies. That means I also built a server for this, using Socket and ServerSocket. It's been of the ordinary blocking kind, and I'm pretty happy. But not complacent. Right now I'm doing some research to see if there's any low-hanging fruit in terms of massive speed gains. The driving business paradigm is that the application is for timekeeping at a company. If I run the code to add a time entry below the server layer, I can add a million time entries per second (thread-safely! It's atomic indexes and ConcurrentHashMap for the shared mutable state). However, if I do the equivalent through the server layer, it's down to eleven thousand per second. Yuck. Well, I mean it's ok and all, but I want a million if there's some easy way to have it. One of the big bottlenecks is the back-and-forth of the HTTP protocol, where the server examines the first line to see what it is (GET? POST? etc) and then reads the headers (Does it have a content-length?, Who is this, per the cookie?) and then assembles a response in kind. It also complicates things that I am handling keep-alive as well. That means the client might decide to stay on the socket for the next back-and-forth. Which leads me to the idea of non-blocking. If I do that, sure, each individual request/response should be the same performance, but with all that waiting taking place in blocking servers, I would imagine I could parallelize this tremendously and get my million requests per second. Questions: 1. Am I insane? 2. Is non-blocking the answer to this? 3. I've looked at Ktor's code. Is there other code that covers similar ground, written in pure Kotlin, test/quality-oriented, that's fast?

[Ktor] Hello! Please, it is possible to read resources/application.conf file in build.gradle? I have database connection stored in application.conf, and need to run scripts which use database connection.

Hello everyone. Any ideas on how to implement microservices with ktor? I am specifically looking for information on the general architecture and how the services communicate with each other. Looking to have the following implemented: • API gateway • Logging • Dashboard e.t.c

hey everyone, need a bit quick help. pseudocode: When there is a “specialCase” error, throw the exception and Log this exception as “Info”. This is the if statement I have. Does this look like a good approach?

if (error.contains (specialCase)) {
    throw specialCaseException
}
    <http://LOGGER.info|LOGGER.info>("logspecialCaseInfoAsInfo")

Hello everybody! Has anyone here ever worked with

Server-Sent Events

? I'm struggling to find clear examples

Hello everyone, Kotlin JPA Entity constructor issue in Java. I working on a spring/java server application. I started refactoring some entities to use Kotlin, but I am having some challenges invoking default constructor from Java class. This is a maven project using kotlin-maven-plugin with jpa, and spring. For some reason i am able to invoke the no arg constructor in java class as new Person(), and when this happens the default values of that object are all set to null, instead of preserving the value that i defined in the Person class. i expect the new Person() to yield a syntax error similar to when it is invoked in Kotlin class, or at least if the default constructor is used/allowed to be invoked from java it should use the default values in the fields. What am i missing?

>The no-arg compiler plugin generates an additional zero-argument constructor for classes with a specific annotation.

The generated constructor is synthetic so it can’t be directly called from Java or Kotlin, but it can be called using reflection.

https://kotlinlang.org/docs/reference/compiler-plugins.html#no-arg-compiler-plugin

example Person.kt

@Entity class Person(
  @Id var id:Long?=0,
  var type:String="A"
){
  var description:String="none"
}

I am creating REST APIs. Where do the APIs pick the values from( in the server side)? What exactly happens at the server side? I want to pass some values daily to the users.

2021-01-22 07:53:46.910 [main] INFO  Application - No ktor.deployment.watch patterns specified, automatic reload is not active
2021-01-22 07:53:47.642 [main] INFO  Application - Responding at <http://0.0.0.0:8080>

I only got this output

Hey @Cheenu Soni Please just create one thread. It will be easy for others to reply.. Have you tried localhost:8080? And also, you have to put a routing for "/" and respond something..

This message was deleted.

Hello! This is a very newbie question but just starting to learn now. When doing a login with social (my example GitHub), I receive an access token from the service then I register the user on my database with username and email, but what do I do with the token? Should I store the token on the database then send it to the client to store there too so they can login? Should I generate my own token and store then send to the client? Or would it be something else? Just trying to understand a bit this concept, seems so complex for me. Thank you!

Does anyone have idea about writing a cron job/ schedule job in Ktor..I want to do some clean up after every 24 hours or hit a remote API and fetch some data and store it in database ?

How to use GRPC?

Following Josh Graham's awesome post about Hotwire on the JVM, I got curious and had a go at supporting it in http4k. Turns out it was really easy so I built an example... 🙂 https://github.com/http4k/examples/tree/master/hotwire

Hello. Have anyone implemented a rest api or microservice using ktor, any dependency injection framework as koin, ddd and clean architecture?

Speak personal! Has anyone here had any experience working with high csv file processing with Kotlin? Could you explain how? Thanks

Can someone explain the 'new JVM backend' introduced in Kotlin 1.4.30

what's the best way to define it in kotlin?

What are people using these days for a multi-process task distribution system, that is tightly integrated with Kotlin and coroutines? I've used Kafka, Akka, ActiveMQ, and Pulsar in the past, but am looking for something a little lighter weight, focused on task distribution, and more Kotlinish. Right now, I'd lean towards Vert.X or Akka, or maybe even building something custom with rsocket.io.

Is there a way to access the call data from ktor to get the principal in my service layer or do I have to pass it down the chain?

I am trying to learn Backend/Frontend development and one of my challenges so far has been to understand JWT authentication. But the more I research this topic the more confused I get. I have seen that storing the JWT token on the frontend's localstorage is a bad thing and I should be doing it via HttpOnly cookies. However for me to use the token on frontend I would need to access it from the cookie, which I can't because it's HttpOnly, so I figured I would just make calls to the backend while having the cookie and the backend would send the data back already authorized, however I was then told that the token should be passed in the authentication header and not in the cookie. So I wanted to ask, what is the correct way to handle this situation? Do I query the backend with the cookie, get the token back, store the token in memory then quary the backend again for data using the token in the authentication header? This sounds a bit counter productive, no? I really want to learn this topic and learn what is the correct way to secure the login.

I updated the driver from 0.8.4 to 0.8.6 and am no longer seeing the warning. Please let me know if there is a potential issue with my code which I need to debug.

Hi all, in case you have missed it! 👋 In Kotlin 1.4.30 :kotlin:, we've announced the Beta stage of the new JVM IR backed. This article describes what it is and why it's important to enable it. But let me repeat the article's central thesis here: please, switch on the JVM IR backend and build your project. And if you will face any problems, please use the YouTrack link or this Slack channel to submit your concern or ask a question.  This version of the JVM backend compiler becomes a default one since 1.5. So, we need to test it very-very well, and for that, we call the Community for this kind of activity. And we hope you will answer our call. With love, Kotlin Team.

My problem is that whenever I open the project lots of code is red and I get "Error: Could not find or load main class dev.yasan.wallpapers.ApplicationKt Caused by: java.lang.ClassNotFoundException: dev.yasan.wallpapers.ApplicationKt" Error. I have not found a proper fix yet. I just have to rebuild the project like 10+ times and it gets fixed randomly. How do I fix this? its really annoying

Is there any document or tutorial about creating a jlink image of a ktor service?

Hey - I’ve got an immutable JPA Entity. It’s got a big String field on it which happens to contain JSON, and I’ve got a method that uses jackson to turn it into a Map. I’d like to memoize the result of that, as it’s never going to change, but lazily so I don’t incur the cost until I need it. But this doesn’t work:

@Entity data class MyImmutableEntity(val jsonString: String) {

  @javax.persistence.Transient private val jsonMap: Map<String, Any> by lazy {
    jacksonObjectMapper().readValue(jsonString)
  }

  fun getJsonMap(): Map<String, Any> = jsonMap
}

The compiler complains about

@Transient

-

This annotation is not applicable to target 'member property with delegate'

. Anyone know of a workaround for this?

Hi, I am playing with ktor and I trying to deploy to google appengine using a uberJar. How can I pass my environment variable ( DATABASE_URL, …. ).