.

core-lib/build.gradle.kts

@@ -0,0 +1,50 @@
+val scrowToken = providers.gradleProperty("scrowMavenToken")
+    .orElse(providers.environmentVariable("SCROW_MAVEN_TOKEN")).get()
+
+plugins {
+    id("java")
+    id("java-library")
+    id("maven-publish")
+}
+
+group = "de.kentoj.scrow"
+version = "0.1"
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    // https://mvnrepository.com/artifact/io.nats/jnats
+    implementation("io.nats:jnats:2.25.2")
+    api("io.nats:jnats:2.25.2")
+
+    // https://mvnrepository.com/artifact/org.mongodb/bson
+    implementation("org.mongodb:bson:5.8.0")
+    api("org.mongodb:bson:5.8.0")
+}
+
+publishing {
+    publications {
+        create<MavenPublication>("CoreLib") {
+            groupId = project.group.toString()
+            artifactId = project.name
+            version = project.version.toString()
+            from(components["java"])
+        }
+    }
+    repositories {
+        maven {
+            name = "scrow"
+            url = uri("http://forge.kentoj.de/api/packages/scrow/maven")
+            isAllowInsecureProtocol = true
+            credentials(HttpHeaderCredentials::class) {
+                name = "Authorization"
+                value = "token $scrowToken"
+            }
+            authentication {
+                create<HttpHeaderAuthentication>("header")
+            }
+        }
+    }
+}

core-lib/src/main/java/de/kentoj/scrowlib/DocumentRepository.java

@@ -0,0 +1,18 @@
+package de.kentoj.scrowlib;
+
+import io.nats.client.Message;
+import lombok.AccessLevel;
+import lombok.NoArgsConstructor;
+import org.bson.Document;
+
+@NoArgsConstructor(access = AccessLevel.PRIVATE)
+public class DocumentRepository {
+
+    public static Document fromMessage(Message message) {
+        return Document.parse(new String(message.getData()));
+    }
+
+    public static byte[] toBytes(Document document) {
+        return document.toJson().getBytes();
+    }
+}

core-lib/src/main/java/de/kentoj/scrowlib/NatsRepository.java

@@ -0,0 +1,43 @@
+package de.kentoj.scrowlib;
+
+import io.nats.client.Connection;
+import io.nats.client.Dispatcher;
+import io.nats.client.Message;
+import org.jetbrains.annotations.NotNull;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+
+public class NatsRepository {
+
+    private final Connection nats;
+
+    private final Dispatcher dispatcher;
+
+    public NatsRepository(Connection nats) {
+        this.nats = nats;
+        this.dispatcher = nats.createDispatcher();
+    }
+
+    public Mono<@NotNull Void> publish(String subject, byte[] data) {
+        return Mono.fromRunnable(() -> nats.publish(subject, data));
+    }
+
+    public Flux<@NotNull Message> subscribe(String subject) {
+        return Flux.create(sink -> {
+                    var handler = dispatcher.subscribe(subject, msg -> {
+                        try {
+                            sink.next(msg);
+                        } catch (Throwable e) {
+                            sink.error(e);
+                        }
+                    });
+
+                    sink.onCancel(handler::unsubscribe);
+                    sink.onDispose(handler::unsubscribe);
+                });
+    }
+
+    public Mono<@NotNull Message> request(String subject, byte[] data) {
+        return Mono.fromFuture(nats.request(subject, data));
+    }
+}