Ktor to 3.0.0 and refactor SSE handling

build.gradle.kts

@@ -7,9 +7,9 @@ val h2_version: String by project
 val postgres_version: String by project
 
 plugins {
-    kotlin("jvm") version "1.9.10"
-    id("io.ktor.plugin") version "2.3.3"
-    id("org.jetbrains.kotlin.plugin.serialization") version "1.9.10"
+    kotlin("jvm") version "2.0.21"
+    id("io.ktor.plugin") version "3.0.0"
+    id("org.jetbrains.kotlin.plugin.serialization") version "2.0.21"
 }
 
 group = "it.rattly"
@@ -24,11 +24,11 @@ application {
 
 repositories {
     mavenCentral()
-    maven { url = uri("https://maven.pkg.jetbrains.space/kotlin/p/kotlin/kotlin-js-wrappers") }
+//    maven { url = uri("https://maven.pkg.jetbrains.space/kotlin/p/kotlin/kotlin-js-wrappers") }
 }
 
 dependencies {
-    implementation("org.jetbrains:kotlin-css-jvm:1.0.0-pre.129-kotlin-1.4.20")
+    implementation("org.jetbrains.kotlin-wrappers:kotlin-css-jvm:1.0.0-pre.818")
 
     implementation("io.ktor:ktor-server-core-jvm")
     implementation("io.ktor:ktor-server-webjars-jvm")
@@ -38,10 +38,18 @@ dependencies {
     implementation("io.ktor:ktor-serialization-kotlinx-json-jvm")
     implementation("io.ktor:ktor-server-html-builder-jvm")
     implementation("io.ktor:ktor-server-cio-jvm")
+    implementation("io.ktor:ktor-server-sse")
 
-    implementation("org.webjars.npm:htmx.org:1.9.4")
+    implementation("org.webjars.npm:htmx.org:2.0.3")
     implementation("org.postgresql:postgresql:$postgres_version")
     implementation("com.h2database:h2:$h2_version")
     implementation("ch.qos.logback:logback-classic:$logback_version")
-    implementation("com.zaxxer:HikariCP:5.0.1")
+    implementation("com.zaxxer:HikariCP:6.0.0")
 }
+
+kotlin {
+    jvmToolchain {
+        languageVersion.set(JavaLanguageVersion.of(21))
+    }
+
+}

gradle.properties

@@ -1,7 +1,7 @@
-ktor_version=2.3.3
-kotlin_version=1.9.10
-logback_version=1.3.11
+ktor_version=3.0.0
+kotlin_version=2.0.21
+logback_version=1.5.10
 kotlin.code.style=official
-exposed_version=0.41.1
-h2_version=2.1.214
-postgres_version=42.5.1
+exposed_version=0.55.0
+h2_version=2.3.232
+postgres_version=42.7.4

gradle/wrapper/gradle-wrapper.properties

@@ -1,5 +1,5 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-7.5.1-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.10.2-all.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists

src/main/kotlin/it/rattly/Application.kt

@@ -5,7 +5,7 @@ import io.ktor.serialization.kotlinx.json.*
 import io.ktor.server.application.*
 import io.ktor.server.cio.*
 import io.ktor.server.engine.*
-import io.ktor.server.plugins.callloging.*
+import io.ktor.server.plugins.calllogging.*
 import io.ktor.server.plugins.compression.*
 import io.ktor.server.plugins.contentnegotiation.*
 import io.ktor.server.request.*
@@ -32,7 +32,7 @@ fun Application.module() {
 fun Application.configureMisc() {
     install(Webjars)
 
-    if (environment.developmentMode)
+    if (developmentMode)
         install(CallLogging) {
             level = Level.INFO
             filter { call -> call.request.path().startsWith("/") }
@@ -46,9 +46,9 @@ fun Application.configureMisc() {
     }
 
     install(Compression) {
-         condition {
-             it.contentType != ContentType.Text.EventStream
-         }
+        condition {
+            it.contentType != ContentType.Text.EventStream
+        }
 
         gzip {
             priority = 1.0

src/main/kotlin/it/rattly/plugins/SSE.kt

@@ -1,51 +1,29 @@
 package it.rattly.plugins
 
-import io.ktor.http.*
 import io.ktor.server.application.*
 import io.ktor.server.plugins.*
-import io.ktor.server.response.*
 import io.ktor.server.routing.*
-import io.ktor.utils.io.*
-import kotlinx.coroutines.flow.Flow
+import io.ktor.server.sse.*
+import io.ktor.sse.*
 import kotlinx.coroutines.flow.MutableSharedFlow
 
-data class SseEvent(val data: String, val event: String? = null, val id: String? = null)
-
-val sseFlow = MutableSharedFlow<SseEvent>()
+val sseFlow = MutableSharedFlow<ServerSentEvent>()
 suspend fun triggerSSE(author: String) {
-    sseFlow.emit(SseEvent(event = "newTodo", data = author))
+    sseFlow.emit(ServerSentEvent(data=author, event = "newTodo"))
 }
 
 fun Application.configureSSE() {
+    install(SSE)
 
     routing {
-        get("/sse") {
-            val id = call.request.queryParameters["uid"] ?: throw BadRequestException("no id")
-            call.respondSse(sseFlow, id)
-        }
-    }
-}
-
-suspend fun ApplicationCall.respondSse(eventFlow: Flow<SseEvent>, id: String) {
-    response.cacheControl(CacheControl.NoCache(null))
-    respondBytesWriter(contentType = ContentType.Text.EventStream) {
-        eventFlow.collect { event ->
-            if (event.data == id)
-                return@collect
-
-            if (event.id != null) {
-                writeStringUtf8("id: ${event.id}\n")
+        sse("/sse") {
+            // not sure, how could we use the UID here
+            // probably, we could track the user sessions,
+            // but it's no use if we cannot track the user as SSE is not designed for this
+            val uid = call.request.queryParameters["uid"] ?: throw BadRequestException("no id")
+            sseFlow.collect {
+                send(it)
             }
-
-            if (event.event != null) {
-                writeStringUtf8("event: ${event.event}\n")
-            }
-
-            for (dataLine in event.data.lines()) {
-                writeStringUtf8("data: $dataLine\n")
-            }
-            writeStringUtf8("\n")
-            flush()
         }
     }
-}
+}

src/main/kotlin/it/rattly/plugins/db/Databases.kt

@@ -2,19 +2,14 @@ package it.rattly.plugins.db
 
 import com.zaxxer.hikari.HikariConfig
 import com.zaxxer.hikari.HikariDataSource
-import io.ktor.http.*
 import io.ktor.server.application.*
-import io.ktor.server.request.*
-import io.ktor.server.response.*
-import io.ktor.server.routing.*
 import it.rattly.plugins.db.todo.TodoService
 import it.rattly.plugins.db.todo.todoRoutes
-import kotlinx.coroutines.*
-import java.sql.*
+import java.sql.Connection
 
 
 fun Application.configureDatabases() {
-    todoRoutes(TodoService(connectToPostgres(System.getenv("USE_EMBEDDED_DB").toBoolean())))
+    todoRoutes(TodoService(connectToPostgres()))
 }
 
 /**
@@ -38,7 +33,7 @@ fun Application.configureDatabases() {
  * @return [Connection] that represent connection to the database. Please, don't forget to close this connection when
  * your application shuts down by calling [Connection.close]
  * */
-fun connectToPostgres(embedded: Boolean): HikariDataSource {
+fun connectToPostgres(embedded: Boolean = true): HikariDataSource {
     Class.forName("org.postgresql.Driver")
 
     val config = HikariConfig().apply {

src/main/kotlin/it/rattly/plugins/db/todo/TodoService.kt

@@ -1,11 +1,10 @@
 package it.rattly.plugins.db.todo
 
 import com.zaxxer.hikari.HikariDataSource
-import it.rattly.plugins.triggerSSE
-import kotlinx.coroutines.*
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
 import kotlinx.serialization.Serializable
 import org.intellij.lang.annotations.Language
-import java.sql.Connection
 import java.sql.Statement
 
 @Serializable

src/main/kotlin/it/rattly/views/layout/_layout.kt

@@ -7,7 +7,7 @@ fun HTML.layout(e: BODY.() -> Unit) {
         link(rel = "stylesheet", href = "https://cdn.simplecss.org/simple.min.css")
         link(rel = "stylesheet", href = "/styles.css", type = "text/css")
 
-        val htmx = { e: String -> "webjars/htmx.org/1.9.4/$e" }
+        val htmx = { e: String -> "webjars/htmx.org/2.0.3/$e" }
         script(src = htmx("dist/htmx.min.js")) {}
         script(src = htmx("dist/ext/json-enc.js")) {}
         script(src = htmx("dist/ext/sse.js")) {}

src/main/kotlin/it/rattly/views/layout/styles.css.kt

@@ -11,12 +11,12 @@ fun Application.configureStyles() = routing {
         call.respondCss {
             // padding left
             rule(".pl") {
-                margin(left = 20.px)
+                marginLeft = 20.px
             }
         }
     }
 }
 
-suspend inline fun ApplicationCall.respondCss(builder: CSSBuilder.() -> Unit) {
-    this.respondText(CSSBuilder().apply(builder).toString(), ContentType.Text.CSS)
+suspend inline fun ApplicationCall.respondCss(builder: CssBuilder.() -> Unit) {
+    this.respondText(CssBuilder().apply(builder).toString(), ContentType.Text.CSS)
 }

src/main/kotlin/it/rattly/views/todos/todo.list.kt

@@ -4,7 +4,6 @@ import it.rattly.views.layout.layout
 import kotlinx.html.*
 import kotlinx.html.InputType.*
 import java.util.*
-import java.util.concurrent.ThreadLocalRandom
 
 fun HTML.listTodos() = layout {
     val uid = UUID.randomUUID()