add examples for services

build.gradle.kts

@@ -1,20 +1,47 @@
 plugins{
-    kotlin("jvm") version "2.0.20"
+    alias(libs.plugins.kotlin.jvm)
+    alias(libs.plugins.ktor)
+}
+
+group = "center.sciprog.demo"
+version = "0.0.1"
+
+application {
+    mainClass.set("serverMainKt")
+
+    val isDevelopment: Boolean = project.ext.has("development")
+    applicationDefaultJvmArgs = listOf("-Dio.ktor.development=$isDevelopment")
 }
 
 repositories {
     mavenCentral()
 }
 
-val ktorVersion = "3.0.1"
-
 dependencies {
-    implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.9.0")
+    implementation(libs.kotlinx.html)
+    implementation(libs.kotlin.css)
+    implementation(libs.logback.classic)
+    implementation(libs.kotlinx.datetime)
 
-    implementation("io.ktor:ktor-client-core:$ktorVersion")
-    implementation("io.ktor:ktor-client-cio:$ktorVersion")
-    implementation("io.ktor:ktor-client-core-jvm:3.0.1")
-    implementation("io.ktor:ktor-client-apache:3.0.1")
 
-    implementation("ch.qos.logback:logback-classic:1.5.12")
+    implementation(libs.ktor.server.core)
+    implementation(libs.ktor.server.websockets)
+    implementation(libs.ktor.server.html.builder)
+    implementation(libs.ktor.server.call.logging)
+    implementation(libs.ktor.server.cors)
+    implementation(libs.ktor.server.host.common)
+    implementation(libs.ktor.server.cio)
+
+    implementation(libs.ktor.client.core)
+    implementation(libs.ktor.client.cio)
+    implementation(libs.ktor.client.websockets)
+
+//    implementation("io.ktor:ktor-client-core:$ktorVersion")
+//    implementation("io.ktor:ktor-client-cio:$ktorVersion")
+//    implementation("io.ktor:ktor-client-core-jvm:3.0.1")
+//    implementation("io.ktor:ktor-client-apache:3.0.1")
+
+    testImplementation(libs.ktor.server.test.host)
+    testImplementation(libs.kotlin.test.junit)
 }
+

gradle/libs.versions.toml

@@ -0,0 +1,30 @@
+[versions]
+kotlin-version = "2.0.21"
+kotlinx-html-version = "0.11.0"
+ktor-version = "3.0.1"
+logback-version = "1.4.14"
+
+[libraries]
+ktor-server-core = { module = "io.ktor:ktor-server-core-jvm", version.ref = "ktor-version" }
+ktor-server-websockets = { module = "io.ktor:ktor-server-websockets-jvm", version.ref = "ktor-version" }
+ktor-server-html-builder = { module = "io.ktor:ktor-server-html-builder-jvm", version.ref = "ktor-version" }
+kotlinx-html = { module = "org.jetbrains.kotlinx:kotlinx-html-jvm", version.ref = "kotlinx-html-version" }
+kotlin-css = { module = "org.jetbrains:kotlin-css-jvm", version = "1.0.0-pre.129-kotlin-1.4.20" }
+ktor-server-call-logging = { module = "io.ktor:ktor-server-call-logging-jvm", version.ref = "ktor-version" }
+ktor-server-cors = { module = "io.ktor:ktor-server-cors-jvm", version.ref = "ktor-version" }
+ktor-server-host-common = { module = "io.ktor:ktor-server-host-common-jvm", version.ref = "ktor-version" }
+ktor-server-cio = { module = "io.ktor:ktor-server-cio-jvm", version.ref = "ktor-version" }
+logback-classic = { module = "ch.qos.logback:logback-classic", version.ref = "logback-version" }
+ktor-server-test-host = { module = "io.ktor:ktor-server-test-host-jvm", version.ref = "ktor-version" }
+kotlin-test-junit = { module = "org.jetbrains.kotlin:kotlin-test-junit", version.ref = "kotlin-version" }
+kotlinx-datetime = "org.jetbrains.kotlinx:kotlinx-datetime:0.6.1"
+
+ktor-client-core = { module = "io.ktor:ktor-client-core", version.ref = "ktor-version" }
+ktor-client-cio = { module = "io.ktor:ktor-client-cio", version.ref = "ktor-version" }
+ktor-client-apache = { module = "io.ktor:ktor-client-apache", version.ref = "ktor-version" }
+ktor-client-websockets = { module = "io.ktor:ktor-client-websockets", version.ref = "ktor-version" }
+
+
+[plugins]
+kotlin-jvm = { id = "org.jetbrains.kotlin.jvm", version.ref = "kotlin-version" }
+ktor = { id = "io.ktor.plugin", version.ref = "ktor-version" }

src/main/kotlin/aggregatorClient.kt

@@ -0,0 +1,54 @@
+import io.ktor.client.HttpClient
+import io.ktor.client.plugins.websocket.WebSockets
+import io.ktor.client.plugins.websocket.webSocket
+import io.ktor.websocket.Frame
+import io.ktor.websocket.readText
+import kotlinx.coroutines.CompletableDeferred
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Deferred
+import kotlinx.coroutines.flow.*
+import kotlinx.coroutines.launch
+import java.time.Instant
+import io.ktor.client.engine.cio.CIO as ClientCIO
+
+suspend fun CoroutineScope.aggregateFromService(url: String): List<Instant> {
+    val client = HttpClient(ClientCIO) {
+        install(WebSockets)
+    }
+
+    val result = CompletableDeferred<List<Instant>>()
+
+    launch {
+        client.webSocket(url) {
+            val res = incoming.receiveAsFlow()
+                .filterIsInstance<Frame.Text>()
+                .take(3)
+                .map { Instant.parse(it.readText()) }
+                .toList()
+
+            result.complete(res)
+        }
+    }
+
+    return result.await()
+}
+
+//suspend fun aggregateFromServiceAsync(url: String): Deferred<List<Instant>> {
+//    val client = HttpClient(ClientCIO) {
+//        install(WebSockets)
+//    }
+//
+//    val result = CompletableDeferred<List<Instant>>()
+//
+//    client.webSocket(url) {
+//        val res = incoming.consumeAsFlow()
+//            .filterIsInstance<Frame.Text>()
+//            .take(3)
+//            .map { Instant.parse(it.readText()) }
+//            .toList()
+//
+//        result.complete(res)
+//    }
+//
+//    return result
+//}

src/main/kotlin/examples/exceptionHandling.kt

@@ -0,0 +1,34 @@
+package examples
+
+import kotlinx.coroutines.*
+
+
+fun main(): Unit = runBlocking{
+    val masterJob = launch(
+        CoroutineExceptionHandler { coroutineContext, throwable ->
+            println(throwable)
+        }
+    ){
+        supervisorScope {
+            val subJob = launch {
+//                println(coroutineContext[Job])
+                delay(100)
+                println("Interrupting")
+                error("BOOM!")
+            }
+
+            val subDeferred = async {
+                delay(200)
+                println("Task completed")
+                "Completed"
+            }
+
+//            subJob.await()
+            println(subDeferred.await())
+        }
+    }
+//    delay(50)
+//    masterJob.cancel()
+    masterJob.join()
+    println("Master job joined")
+}

src/main/kotlin/examples/javaHttpClient.kt

@@ -1,3 +1,5 @@
+package examples
+
 import java.net.*
 import java.net.http.*
 import java.net.http.HttpResponse.*
@@ -13,11 +15,11 @@ fun main() {
 
     client.sendAsync(request, BodyHandlers.ofString())
         .thenApply{ it.body() }
-        .thenApply{
-            val resources = regex.findAll(it).map{it.groupValues[1]}
+        .thenApply{ body ->
+            val resources = regex.findAll(body).map{it.groupValues[1]}
 
-            resources.map { resourceName->
-                println("Resource processing for $resourceName started")
+            resources.toList().map { resourceName->
+                println("Resource processing for $resourceName")
                 val resourceRequest :  HttpRequest = HttpRequest.newBuilder()
                     .uri(URI.create("https://sciprog.center$resourceName"))
                     .GET().build()
@@ -26,6 +28,8 @@ fun main() {
                     //do something with the body
                     println("The resource with name $resourceName has ${bodyBytes.size} bytes")
                 }
+            }.forEach {
+                it.join()
             }
             resources
         }

src/main/kotlin/examples/jobExample.kt

@@ -0,0 +1,32 @@
+package examples
+
+import kotlinx.coroutines.async
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.runBlocking
+
+
+fun main() = runBlocking {
+
+    val job1 = launch {
+        delay(200)
+        println("Job1 completed")
+    }
+
+    val deferred1 = async {
+        delay(200)
+        return@async "Complete"
+    }
+
+    val job2 = launch {
+        delay(100)
+        job1.cancel()
+        println("Job1 canceled")
+        deferred1.cancel()
+        println("Deferred1 canceled")
+    }
+
+    job1.join()
+    println("Job1 joined")
+    println(deferred1.await())
+}

src/main/kotlin/examples/ktorClient.kt

@@ -1,5 +1,6 @@
+package examples
+
 import io.ktor.client.HttpClient
-import io.ktor.client.call.body
 import io.ktor.client.engine.cio.CIO
 import io.ktor.client.request.get
 import io.ktor.client.statement.bodyAsBytes
@@ -24,3 +25,4 @@ suspend fun main() = coroutineScope {
         }
     }
 }
+

src/main/kotlin/microservice/asyncResponse.kt

@@ -0,0 +1,45 @@
+package microservice
+
+typealias RequestArgs = Map<String, String>
+typealias ComputationData = Map<String, String>
+typealias Response = Map<String, String>
+
+data class ServerRequest(
+    val user: String,
+    val token: String,
+    val action: String,
+    val arguments: RequestArgs
+)
+
+interface ValidationService {
+    suspend fun isValid(user: String, token: String, action: String): Boolean
+}
+
+interface DataBaseService {
+    suspend fun provide(arguments: RequestArgs): ComputationData
+}
+
+interface ComputationService {
+    suspend fun compute(action: String, arguments: ComputationData): Response
+}
+
+class ComputationContext(
+    val validationService: ValidationService,
+    val dataBaseServiceA: DataBaseService,
+    val dataBaseServiceB: DataBaseService,
+    val dataBaseServiceC: DataBaseService,
+    val computationService: ComputationService
+)
+
+suspend fun ComputationContext.respond(request: ServerRequest): Response {
+    val isValid = validationService.isValid(request.user, request.token, request.action)
+    if (isValid) {
+        val dataA = dataBaseServiceA.provide(request.arguments)
+        val dataB = dataBaseServiceB.provide(request.arguments)
+        val dataC = dataBaseServiceC.provide(request.arguments)
+        val result = computationService.compute(request.action, dataA + dataB + dataC)
+        return result
+    } else {
+        error("Illegal access")
+    }
+}

src/main/kotlin/microservice/pricingService.kt

@@ -0,0 +1,69 @@
+package microservice
+
+import kotlinx.coroutines.*
+import kotlinx.datetime.Clock
+import kotlinx.datetime.Instant
+import java.math.BigDecimal
+import kotlin.time.Duration
+import kotlin.time.Duration.Companion.minutes
+import kotlin.time.Duration.Companion.seconds
+
+interface PriceReader {
+    suspend fun readPrice(): BigDecimal
+}
+
+interface PriceWriter {
+    suspend fun writePrice(price: BigDecimal)
+}
+
+interface PriceDB {
+    suspend fun storePrice(time: Instant, price: BigDecimal)
+
+    suspend fun restorePrice(timeRange: ClosedRange<Instant>): List<Pair<Instant, BigDecimal>>
+}
+
+
+private suspend fun computePrice(history: List<Pair<Instant, BigDecimal>>): BigDecimal = TODO()
+
+private val readDelay = 5.seconds
+private val writeDelay = 10.seconds
+
+fun CoroutineScope.launchPriceUpdate(
+    reader: PriceReader,
+    writer: PriceWriter,
+    db: PriceDB,
+    duration: Duration
+): Job = launch {
+    val cache = ArrayDeque<Pair<Instant, BigDecimal>>()
+
+
+    //read job
+    launch {
+        while (isActive) {
+            delay(readDelay)
+            val now = Clock.System.now()
+            val price = reader.readPrice()
+            db.storePrice(now, price)
+            cache.addFirst(now to price)
+        }
+    }
+
+    //write job
+    launch {
+        while (isActive) {
+            delay(writeDelay)
+            val now = Clock.System.now()
+            val computedPrice = computePrice(cache.filter { it.first > (now - duration) })
+            writer.writePrice(computedPrice)
+        }
+    }
+
+    //cache cleanup job
+    launch {
+        while (isActive) {
+            delay(1.minutes)
+            val now = Clock.System.now()
+            cache.removeIf { now - it.first > duration }
+        }
+    }
+}

src/main/kotlin/serverMain.kt

@@ -0,0 +1,78 @@
+import io.ktor.http.HttpStatusCode
+import io.ktor.server.application.install
+import io.ktor.server.cio.CIO
+import io.ktor.server.engine.embeddedServer
+import io.ktor.server.request.receiveText
+import io.ktor.server.response.respond
+import io.ktor.server.response.respondText
+import io.ktor.server.routing.Route
+import io.ktor.server.routing.get
+import io.ktor.server.routing.post
+import io.ktor.server.routing.route
+import io.ktor.server.routing.routing
+import io.ktor.server.websocket.WebSockets
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.coroutineScope
+import kotlinx.coroutines.currentCoroutineContext
+import kotlinx.coroutines.newFixedThreadPoolContext
+import kotlinx.coroutines.sync.Semaphore
+import kotlinx.coroutines.sync.withPermit
+import kotlinx.coroutines.withContext
+import kotlin.coroutines.CoroutineContext
+
+fun Route.subroute(){
+    var content = ""
+
+    get("get") {
+        call.respondText("Content: ${content}")
+    }
+
+    post("set"){
+        content = call.receiveText()
+        call.respond(HttpStatusCode.OK)
+    }
+}
+
+suspend fun executeQuery(queryName: String, ioContext: CoroutineContext = Dispatchers.IO): String{
+    withContext(ioContext){
+        //some blocking logic
+    }
+    return queryName
+}
+
+
+fun main() {
+    embeddedServer(CIO, port = 8080, host = "localhost") {
+        install(WebSockets)
+
+        val ioContext = newFixedThreadPoolContext(12, "DB") //Dispatchers.IO
+
+        routing {
+            get("/") {
+                val callerName = call.queryParameters["name"] ?: "World"
+                call.respondText("Hello $callerName!")
+            }
+            get("/query/{queryName}"){
+                val queryName = call.parameters["queryName"] ?: "query"
+                val queryResult = executeQuery(queryName, ioContext)
+                call.respondText("$queryName successful: $queryResult")
+            }
+            route("subroute"){
+                subroute()
+            }
+            route("subroute1"){
+                subroute()
+            }
+
+            route("producer"){
+                streamingModule()
+            }
+
+            get("aggregated"){
+                val result = aggregateFromService("ws://localhost:8080/producer")
+                call.respondText(result.toString())
+            }
+
+        }
+    }.start(wait = true)
+}

src/main/kotlin/streamingModule.kt

@@ -0,0 +1,39 @@
+import io.ktor.server.routing.Route
+import io.ktor.server.routing.application
+import io.ktor.server.websocket.webSocket
+import io.ktor.websocket.Frame
+import kotlinx.coroutines.channels.Channel
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.isActive
+import kotlinx.coroutines.launch
+import java.time.Instant
+import kotlin.time.Duration.Companion.microseconds
+import kotlin.time.Duration.Companion.milliseconds
+import kotlin.time.Duration.Companion.seconds
+
+
+fun Route.streamingModule() {
+    val channel = Channel<Instant>()
+
+    application.launch {
+        while (isActive) {
+            delay(0.1.seconds)
+            channel.send(Instant.now())
+        }
+    }
+
+    webSocket {
+        repeat(3){
+            delay(100.milliseconds)
+            outgoing.send(Frame.Text(Instant.now().toString()))
+
+        }
+
+//        launch {
+//            while (isActive) {
+//                outgoing.send(Frame.Text(channel.receive().toString()))
+//            }
+//        }
+    }
+}
+