src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/ServerApp.java

@@ -1,5 +1,8 @@
 package ch.unibas.dmi.dbis.cs108.casono.server;
 
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.ping.PingHandler;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.ping.PingParser;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.ping.PingRequest;
 import ch.unibas.dmi.dbis.cs108.casono.server.domain.user.UserCleanupJob;
 import ch.unibas.dmi.dbis.cs108.casono.server.domain.user.UserRegistry;
 import ch.unibas.dmi.dbis.cs108.casono.server.network.NetworkManager;
@@ -7,6 +10,7 @@ import ch.unibas.dmi.dbis.cs108.casono.server.network.command.execution.CommandR
 import ch.unibas.dmi.dbis.cs108.casono.server.network.command.parsing.CommandParserDispatcher;
 import ch.unibas.dmi.dbis.cs108.casono.server.network.events.DisconnectEvent;
 import ch.unibas.dmi.dbis.cs108.casono.server.network.events.EventBus;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.response.dispatcher.ResponseDispatcher;
 import ch.unibas.dmi.dbis.cs108.casono.server.network.sessions.SessionDisconnectJob;
 import ch.unibas.dmi.dbis.cs108.casono.server.network.sessions.SessionManager;
 import java.time.Duration;
@@ -58,6 +62,25 @@ public class ServerApp {
                 SESSION_DISCONNECT_JOB_PERIOD,
                 TimeUnit.SECONDS);
 
+        ResponseDispatcher responseDispatcher = new ResponseDispatcher(sessionManager);
+
+        registerCommands(dispatcher, router, responseDispatcher);
+
         networkManager.start();
     }
+
+    /**
+     * Registers command parsers and handlers.
+     *
+     * @param parserDispatcher the dispatcher responsible for parsing incoming commands
+     * @param commandRouter the router that dispatches parsed commands to appropriate handlers
+     * @param responseDispatcher the dispatcher responsible for sending responses back to clients
+     */
+    private static void registerCommands(
+            CommandParserDispatcher parserDispatcher,
+            CommandRouter commandRouter,
+            ResponseDispatcher responseDispatcher) {
+        parserDispatcher.register("PING", new PingParser());
+        commandRouter.register(PingRequest.class, new PingHandler(responseDispatcher));
+    }
 }

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/ping/PingHandler.java

@@ -0,0 +1,29 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.app.commands.ping;
+
+import ch.unibas.dmi.dbis.cs108.casono.server.network.command.execution.CommandHandler;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.response.OkResponse;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.response.dispatcher.ResponseDispatcher;
+
+/** Handler for {@link PingRequest}. */
+public class PingHandler implements CommandHandler<PingRequest> {
+    private final ResponseDispatcher responseDispatcher;
+
+    /**
+     * Create a new PingHandler to execute {@link PingRequest}s
+     *
+     * @param responseDispatcher dispatcher used to send responses back to clients
+     */
+    public PingHandler(ResponseDispatcher responseDispatcher) {
+        this.responseDispatcher = responseDispatcher;
+    }
+
+    /**
+     * Execute the ping request.
+     *
+     * @param request the ping request to handle
+     */
+    @Override
+    public void execute(PingRequest request) {
+        responseDispatcher.dispatch(new OkResponse(request.getContext()));
+    }
+}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/ping/PingParser.java

@@ -0,0 +1,22 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.app.commands.ping;
+
+import ch.unibas.dmi.dbis.cs108.casono.server.network.command.parsing.CommandParser;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.request.PrimitiveRequest;
+
+/**
+ * Parser for the Ping command.
+ *
+ * <p>Converts a low-level {@link PrimitiveRequest} into a {@link PingRequest}.
+ */
+public class PingParser implements CommandParser<PingRequest> {
+    /**
+     * Parse the given primitive request into a {@link PingRequest}.
+     *
+     * @param primitiveRequest the raw request to parse
+     * @return {@link PingRequest}
+     */
+    @Override
+    public PingRequest parse(PrimitiveRequest primitiveRequest) {
+        return new PingRequest(primitiveRequest.context());
+    }
+}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/ping/PingRequest.java

@@ -0,0 +1,19 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.app.commands.ping;
+
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.request.Request;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.request.RequestContext;
+
+/**
+ * Represents a "PING" request sent by a client to check server availability and keep the connection
+ * alive.
+ */
+public class PingRequest extends Request {
+    /**
+     * Constructs a new PingRequest with the given context.
+     *
+     * @param context the request context associated with this request
+     */
+    public PingRequest(RequestContext context) {
+        super(context);
+    }
+}