.

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

@@ -1,4 +1,4 @@
-package de.kentoj.scrowlib;
+package de.kentoj.scrowlib.messaging;
 
 import io.nats.client.Message;
 import lombok.AccessLevel;

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

@@ -1,4 +1,4 @@
-package de.kentoj.scrowlib;
+package de.kentoj.scrowlib.messaging;
 
 import io.nats.client.Connection;
 import io.nats.client.Dispatcher;

core-lib/src/main/java/de/kentoj/scrowlib/servermanager/CrownServerManager.java

@@ -0,0 +1,72 @@
+package de.kentoj.scrowlib.servermanager;
+
+import com.google.common.base.Preconditions;
+import com.google.common.io.Files;
+import de.kentoj.scrowlib.messaging.DocumentRepository;
+import de.kentoj.scrowlib.messaging.NatsRepository;
+import io.nats.client.Connection;
+import org.bson.Document;
+import org.jetbrains.annotations.NotNull;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+
+public class CrownServerManager implements ServerManager {
+
+    private final NatsRepository natsRepo;
+
+    public CrownServerManager(Connection nats) {
+        this.natsRepo = new NatsRepository(nats);
+    }
+
+    @Override
+    public Mono<@NotNull ServerInstance> deployServer(String template) {
+        var payload = DocumentRepository.toBytes(new Document("template", template));
+        return natsRepo.request("crown.deploy-server", payload)
+                .map(DocumentRepository::fromMessage)
+                .map(doc -> new ServerInstance(
+                        doc.getString("handle"),
+                        doc.getInteger("port")
+                ));
+    }
+
+    @Override
+    public Flux<@NotNull ServerInstance> getRunningServers() {
+        var payload = DocumentRepository.toBytes(new Document());
+        return natsRepo.request("crown.list-servers", payload)
+                .map(DocumentRepository::fromMessage)
+                .map(doc ->
+                        doc.getList("instances", Document.class)
+                )
+                .flatMapIterable(l -> l)
+                .map(doc -> new ServerInstance(
+                        doc.getString("handle"),
+                        doc.getInteger("port"),
+                        doc.getString("state")
+                ));
+    }
+
+    @Override
+    public Mono<@NotNull Void> destroyServer(String handle) {
+        var payload = DocumentRepository.toBytes(new Document("handle", handle));
+        return natsRepo.request("crown.destroy-server", payload)
+                .then();
+    }
+
+    @Override
+    public Mono<@NotNull String> getState(String handle) {
+        var payload = DocumentRepository.toBytes(new Document("handle", handle));
+        return natsRepo.request("crown.get-state", payload)
+                .map(DocumentRepository::fromMessage)
+                .map(doc -> doc.getString("state"));
+    }
+
+    @Override
+    public Mono<@NotNull Void> setState(String handle, String state) {
+        Preconditions.checkArgument(!state.contains(" "), "state may not contain spaces");
+        var payload = DocumentRepository.toBytes(new Document()
+                .append("handle", handle)
+                .append("state", state));
+        return natsRepo.request("crown.set-state", payload)
+                .then();
+    }
+}

core-lib/src/main/java/de/kentoj/scrowlib/servermanager/ServerInstance.java

@@ -0,0 +1,16 @@
+package de.kentoj.scrowlib.servermanager;
+
+import lombok.AllArgsConstructor;
+import lombok.Value;
+
+@Value
+@AllArgsConstructor
+public class ServerInstance {
+    String handle;
+    int port;
+    String state;
+
+    public ServerInstance(String handle, int port) {
+        this(handle, port, "STARTING");
+    }
+}

core-lib/src/main/java/de/kentoj/scrowlib/servermanager/ServerManager.java

@@ -0,0 +1,27 @@
+package de.kentoj.scrowlib.servermanager;
+
+import org.jetbrains.annotations.NotNull;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+
+public interface ServerManager {
+
+    /**
+     * @return Mono with handle of deployed server
+     */
+    Mono<@NotNull ServerInstance> deployServer(String template);
+
+    /**
+     * @return Flux with handles of running servers
+     */
+    Flux<@NotNull ServerInstance> getRunningServers();
+
+    /**
+     * Attempts a clean shutdown, if that doesn't succeed, kills the server.
+     */
+    Mono<@NotNull Void> destroyServer(String handle);
+
+    Mono<@NotNull String> getState(String handle);
+
+    Mono<@NotNull Void> setState(String handle, String state);
+}