.gitlab/issue_templates/Bug Report.md

@@ -0,0 +1,40 @@
+## Bug Report
+<!-- The reccommended type is: Issue -->
+
+### Environment
+- **Branch & Commit:** 
+- **Operating system:** 
+- **How was execution started (Gradle task / IDE debug / IDE run):** 
+- **Java version:** `25`
+- **Gradle version**: `9.3.1`
+
+### Summary
+<!-- Short, precise description of the bug -->
+
+### Expected Behavior
+<!-- What you expected to happen -->
+
+### Actual Behavior
+<!-- What actually happened instead -->
+
+### Steps to Reproduce
+<!--
+1. Do this first
+2. Then do that next
+3. Lastly, see the unexprected ...
+-->
+
+### Stack Trace / Error Message
+```
+<!-- Paste stack trace or log output here -->
+```
+
+### Possible Cause / Notes
+<!-- Optional: your own hypothesis about the root cause -->
+
+### Checklist
+- [ ] I reproduced the problem using the steps above
+- [ ] I searched documentation docs for relevant information
+- [ ] I added relevant labels
+
+/label ~bug

.gitlab/issue_templates/Feature Request.md

@@ -0,0 +1,18 @@
+## Feature Request
+<!-- The reccommended type is: Task -->
+
+### Summary
+<!-- Brief description of the desired functionality -->
+
+### Required workarround
+<!-- Workarround required to achieve x (if applicable) -->
+
+### Description
+<!-- Detailed description of the desired behavior -->
+
+### Checklist
+- [ ] I reproduced the problem using the steps above
+- [ ] I searched documentation docs for relevant information
+- [ ] I added relevant labels
+
+/label ~enhancement

.gitlab/issue_templates/Task.md

@@ -0,0 +1,24 @@
+## Task
+<!-- The reccommended type is: Task -->
+
+### Summary
+<!-- What needs to be implemented? -->
+
+### Context
+<!-- Which part of the system does it belong to? -->
+<!-- Examples: Networking, Game-Engine, User interface, ... -->
+
+### Current Progress
+- [ ] 
+- [ ] 
+- [ ] 
+
+### Notes
+<!-- Optional: Implementation hints, links to prior design discussions, etc. -->
+
+### Checklist
+- [ ] I outlined checkpoints describing phases of my work related to this task
+- [ ] I added relevant labels
+- [ ] I linked to other issues or branches that must be completed first
+
+/label ~task

.gitlab/issue_templates/bug_report_client.md

@@ -1,31 +0,0 @@
-## Bug Report
-
-### Summary
-<!-- Short, precise description of the bug -->
-
-### Affected Component
-<!-- e.g. Lobby Menu, Global Chat, Loading screen, ... -->
-
-### Steps to Reproduce
-1. Do this first
-2. Then do that next
-3. Lastly, see the unexprected error message ...
-
-### Expected Behavior
-<!-- What should happen? -->
-
-### Actual Behavior
-<!-- What happens instead? -->
-
-### Stack Trace / Error Message
-```
-<!-- Paste stack trace or log output here -->
-```
-
-### Possible Cause
-<!-- Optional: your own hypothesis about the root cause -->
-
-
-/label ~bug
-
-/label ~client

.gitlab/issue_templates/bug_report_server.md

@@ -1,30 +0,0 @@
-## Bug Report
-
-### Summary
-<!-- Short, precise description of the bug -->
-
-### Affected Component
-<!-- e.g. TransportLayer, CommandRouter, UserRegistry, Response, ... -->
-
-### Steps to Reproduce
-1. Do this first
-2. Then do that next
-3. Lastly, see the unexprected error message ...
-
-### Expected Behavior
-<!-- What should happen? -->
-
-### Actual Behavior
-<!-- What happens instead? -->
-
-### Stack Trace / Error Message
-```
-<!-- Paste stack trace or log output here -->
-```
-
-### Possible Cause
-<!-- Optional: your own hypothesis about the root cause -->
-
-/label ~bug
-
-/label ~server

.gitlab/issue_templates/feature_request_client.md

@@ -1,27 +0,0 @@
-## Feature Request
-
-### Summary
-<!-- Brief description of the desired functionality -->
-
-### Motivation / Problem
-<!-- What problem does this feature solve? Why is it needed? -->
-
-### Description
-<!-- Detailed description of the desired behavior -->
-
-### Affected Components
-<!-- Which existing components are affected or need to be extended? -->
-<!-- e.g. Lobby Menu, Global Chat, Loading screen, … -->
-
-### Acceptance Criteria
-<!-- What must be fulfilled for this feature to be considered done? -->
-- [ ] 
-- [ ] 
-- [ ] 
-
-### Open Questions / Trade-offs
-<!-- Are there design decisions that still need to be discussed? -->
-
-/label ~enhancement
-
-/label ~client

.gitlab/issue_templates/feature_request_server.md

@@ -1,27 +0,0 @@
-## Feature Request
-
-### Summary
-<!-- Brief description of the desired functionality -->
-
-### Motivation / Problem
-<!-- What problem does this feature solve? Why is it needed? -->
-
-### Description
-<!-- Detailed description of the desired behavior -->
-
-### Affected Components
-<!-- Which existing components are affected or need to be extended? -->
-<!-- e.g. CommandRouter, SessionManager, UserRegistry, … -->
-
-### Acceptance Criteria
-<!-- What must be fulfilled for this feature to be considered done? -->
-- [ ] 
-- [ ] 
-- [ ] 
-
-### Open Questions / Trade-offs
-<!-- Are there design decisions that still need to be discussed? -->
-
-/label ~enhancement
-
-/label ~server

.gitlab/issue_templates/protocol_change.md

@@ -1,37 +0,0 @@
-## Protocol / API Change
-
-### Summary
-<!-- Brief description of the protocol change -->
-
-### Affected Commands / Responses
-<!-- Which commands or response types are being added, changed, or removed? -->
-
-| Command | Response | Type of Change | Description |
-|---------|----------|----------------|-------------|
-|         |          | New / Changed / Removed | |
-
-### New / Changed Syntax
-```
-<!-- Before / after or new command syntax here -->
-<!-- Example:
-BEFORE: LOGIN UNAME=<username> PASS=<password>
-AFTER:  LOGIN USERNAME=<username> PASSWORD=<password>
--->
-```
-
-### Affected Implementation Layers
-<!-- Which components / classes need to be updated? -->
-- [ ] `Session`
-- [ ] `User` or `UserRegistry`
-- [ ] `Tokenizer` / `RequestTokenClassifier`
-- [ ] `ProtocolParser`
-- [ ] `CommandParserDispatcher` + corresponding `CommandParser`
-- [ ] `CommandHandler`
-- [ ] `Response` hierarchy
-- [ ] `GameEngine` or `GameState`
-- [ ] Client-side (create your own issue and create link)
-
-### Motivation
-<!-- Why is this protocol change necessary? -->
-
-/label ~protocol

.gitlab/issue_templates/task_client.md

@@ -1,25 +0,0 @@
-## Task
-
-### Summary
-<!-- What needs to be implemented? -->
-
-### Context
-<!-- Which part of the system does it belong to? -->
-
-### Affected Components
-<!-- e.g. Controller, View, Model, Network, ... -->
-
-### Definition of Done
-- [ ] 
-- [ ] 
-- [ ] 
-
-### Notes
-<!-- Optional: implementation hints, links to prior design discussions, etc. -->
-
-### Checklist
-- [ ] Linked to other issues or branches that must be completed first?
-
-/label ~task
-
-/label ~client

.gitlab/issue_templates/task_server.md

@@ -1,25 +0,0 @@
-## Task
-
-### Summary
-<!-- What needs to be implemented? -->
-
-### Context
-<!-- Which part of the system does it belong to? -->
-
-### Affected Components
-<!-- e.g. Response hierarchy, CommandRouter, UserRegistry, ... -->
-
-### Definition of Done
-- [ ] 
-- [ ] 
-- [ ] 
-
-### Notes
-<!-- Optional: implementation hints, links to prior design discussions, etc. -->
-
-### Checklist
-- [ ] Linked to other issues or branches that must be completed first?
-
-/label ~task
-
-/label ~server

CONTRIBUTING.md

@@ -0,0 +1,208 @@
+# Contribution Guidelines
+This document describes the conventions and workflows everyone must follow to keep the codebase consistent and the collaboration smooth. 
+If you notice a violation, speak to the person involved respectfully. 
+
+Since this project is part of a course at the University of Basel, the [Code of Conduct](https://www.unibas.ch/de/Universitaet/Administration-Services/Vizerektorat-People-And-Culture/Persoenliche-Integritaet/Code-of-Conduct.html) applies.
+
+
+## Table of Contents
+- [Contribution Guidelines](#contribution-guidelines)
+  - [Table of Contents](#table-of-contents)
+  - [Issues \& Tasks](#issues--tasks)
+    - [Creating an issue](#creating-an-issue)
+    - [During implementation](#during-implementation)
+    - [Collaborative work](#collaborative-work)
+  - [Git Workflow](#git-workflow)
+    - [Creating a branch](#creating-a-branch)
+    - [Working on a branch](#working-on-a-branch)
+  - [Commit Messages](#commit-messages)
+    - [Rules](#rules)
+    - [Examples](#examples)
+  - [Code Style](#code-style)
+    - [Linter](#linter)
+    - [Formatter](#formatter)
+    - [General guidelines](#general-guidelines)
+  - [CI/CD Pipeline](#cicd-pipeline)
+    - [Before pushing](#before-pushing)
+  - [Merge Requests](#merge-requests)
+    - [Opening a MR](#opening-a-mr)
+    - [Merging](#merging)
+    - [After merging](#after-merging)
+  - [Be human](#be-human)
+
+
+## Issues & Tasks
+Every piece of work - whether a new feature, a bug fix, or a refactoring - must be tracked as an
+Issue or Task in GitLab **before** any implementation begins.
+
+### Creating an issue
+1. Open a new Issue or Task using the **relevant template** provided in the repository.
+2. Fill in **all fields** specified by the template thoughtfully and completely. A well-written issue is the single source of truth for the work being done - treat it accordingly.
+3. Work through the **checklist** in the template before marking the issue as ready. Do not skip items.
+
+### During implementation
+- If you encounter a problem or an unexpected finding while working on an issue, record it as a **comment** on the issue. This keeps the history intact and visible to the whole team.
+- **Do not restructurally edit the original description** to incorporate new information. The description reflects the intent at the time the issue was created; comments document what happened along the way.
+
+### Collaborative work
+- When multiple people are working on the same issue, **prefer issue comments over private messages** for coordination. This keeps the current status, decisions, and open questions
+  centrally visible and searchable.
+- Before starting work that overlaps with an existing issue, check its comment thread first to avoid duplicating effort.
+
+
+## Git Workflow
+We use a **feature branch -> main** strategy. The `main` branch is always in a releasable state.
+
+### Creating a branch
+We follow the [**Conventional Branch**](https://conventional-branch.github.io/) specification. Branch names follow this pattern:
+
+```
+<type>/<short-description>
+```
+
+| Type       | When to use                                      |
+|------------|--------------------------------------------------|
+| `feat`     | New feature or capability                        |
+| `fix`      | Bug fix                                          |
+| `refactor` | Restructuring without behaviour change           |
+| `test`     | Adding or fixing tests                           |
+| `ci`       | Pipeline, Gradle, or tooling changes             |
+| `docs`     | Documentation only                               |
+
+**Examples:**
+
+```
+feat/reconnect-command
+fix/session-writer-flush
+refactor/user-registry-cleanup
+docs/contributing
+```
+
+### Working on a branch
+Keep branches short-lived. A branch should represent one cohesive unit of work.
+
+It is permissible to commit changes within a feature branch that cause the program to become non-functional, but these should be fixed as soon as possible. In any case, the code that is merged into `main` must be functional.
+
+And most importantly: **Do not commit directly to `main`**.
+
+
+## Commit Messages
+We follow the [**Conventional Commits**](https://www.conventionalcommits.org/) specification. Every commit message must have the form:
+
+```
+<type>: <short summary>
+
+[optional body]
+```
+
+### Rules
+The summary line must be **<= 72 characters**, written in the **imperative mood** (e.g. "add", not "added" or "adds").
+
+### Examples
+```
+Reat: Add RECONNECT command handler
+
+The handler re-associates an existing User with a new Session after
+a connection drop, preserving in-flight state.
+```
+
+```
+Fix: Flush output stream before closing
+```
+
+```
+Ci: Tighten Checkstyle failure policy to allow_failure: false
+```
+
+```
+Refactor: Replace ArrayList with CopyOnWriteArrayList
+```
+
+
+## Code Style
+Code formatting is enforced automatically. **Do not submit a MR with formatting violations.**
+
+### Linter
+We use **Checkstyle** as our linter with a custom set of rules tailored to our project.
+
+Checkstyle runs on every pipeline. Fix all violations locally before pushing:
+
+```bash
+./gradlew checkstyleMain checkstyleTest
+```
+
+
+### Formatter
+We use **Spotless** with the **[Google](https://google.github.io/styleguide/javaguide.html) / [AOSP Java style](https://source.android.com/docs/core/architecture/hidl/code-style?hl=en)**:
+
+- **Indentation:** 4 spaces (no tabs)
+- **Line length:** 100 characters
+- No decorative blank lines directly after opening braces `{`
+- Blank lines are reserved for separating logical sections within a block
+
+Run the formatter before committing:
+
+```bash
+./gradlew spotlessApply
+```
+
+Check without applying:
+
+```bash
+./gradlew spotlessCheck
+```
+
+### General guidelines
+- Add **JavaDoc** docstrings to classes, interfaces, records and methods.
+- Exercise **clean architecture**
+- Prefer **stateless components**
+- Use **`record` types** for immutable data carriers.
+- Log with **Log4J 2** (`log4j-api`). Use the appropriate level (`DEBUG` for pipeline internals, `INFO` for lifecycle events, `WARN`/`ERROR` for recoverable/unrecoverable problems).
+
+
+## CI/CD Pipeline
+The pipeline runs automatically on every push. It has four stages:
+
+```
+lint > report > build > test
+```
+
+| Stage    | Jobs                                       |
+|----------|--------------------------------------------|
+| `lint`   | Spotless check, Checkstyle                 |
+| `report` | Code Quality JSON conversion (only for mr) |
+| `build`  | `./gradlew assemble`                       |
+| `test`   | `./gradlew test` + JUnit result reporting  |
+
+### Before pushing
+Run the full check suite locally to avoid a broken pipeline:
+
+```bash
+./gradlew spotlessCheck checkstyleMain checkstyleTest build test
+```
+
+A red pipeline blocks merging. Fix failures before creating your merge request.
+
+
+## Merge Requests
+
+### Opening a MR
+- Target branch is always **`main`**.
+- Fill in the MR description: what changed and why. Link the relevant issue (with 'Closing #x') if one exists.
+
+### Merging
+A MR can be merged when **all main CI pipeline stages are green** (lint, build, test).
+
+No explicit peer approval is required, but leaving a note or question in the MR thread for non-trivial changes is encouraged.
+If you spot a problem in someone else's open MR, comment - **do not push directly to their branch** and try to fix the issue yourself.
+
+### After merging
+Delete the feature branch after the MR is merged. GitLab can do this automatically via the
+"Delete source branch" checkbox in the MR.
+
+
+## Be human
+We are all human.
+We all forget things or make mistakes sometimes.
+
+It’s important that we look out for one another and **work together as a team**.

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

@@ -3,8 +3,10 @@ package ch.unibas.dmi.dbis.cs108.casono.server;
 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;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.command.CommandRouter;
 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.parser.CommandParserDispatcher;
 import ch.unibas.dmi.dbis.cs108.casono.server.network.sessions.SessionManager;
 import java.time.Duration;
 import java.util.concurrent.Executors;
@@ -26,7 +28,10 @@ public class ServerApp {
         logger.info("Starting server at port {}", port);
 
         EventBus eventBus = new EventBus();
-        SessionManager sessionManager = new SessionManager(eventBus);
+        CommandParserDispatcher dispatcher = new CommandParserDispatcher();
+        CommandRouter router = new CommandRouter();
+
+        SessionManager sessionManager = new SessionManager(eventBus, dispatcher, router);
         eventBus.subscribe(DisconnectEvent.class, event -> sessionManager.onDisconnect(event));
         NetworkManager networkManager = new NetworkManager(port, sessionManager);
 

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/command/CommandHandler.java

@@ -0,0 +1,7 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.network.command;
+
+import ch.unibas.dmi.dbis.cs108.casono.server.network.parser.Request;
+
+public interface CommandHandler<T extends Request> {
+    void execute(T request);
+}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/command/CommandRouter.java

@@ -0,0 +1,28 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.network.command;
+
+import ch.unibas.dmi.dbis.cs108.casono.server.network.parser.Request;
+import java.util.HashMap;
+import java.util.Map;
+
+public class CommandRouter {
+    private final Map<Class<? extends Request>, CommandHandler<?>> handlers = new HashMap<>();
+
+    public <T extends Request> void register(Class<T> request, CommandHandler<T> handler) {
+        handlers.put(request, handler);
+    }
+
+    // Safe, because during registration, it's ensured that the provided CommandHandler only
+    // receives requests it can handle.
+    @SuppressWarnings("unchecked")
+    public void execute(Request request) {
+        CommandHandler<Request> handler =
+                (CommandHandler<Request>) handlers.get(request.getClass());
+
+        if (handler == null) {
+            String requestName = request.getClass().toString();
+            throw new UnknownRequestException(
+                    "Unable to execute request " + requestName + ". Type unknown", requestName);
+        }
+        handler.execute(request);
+    }
+}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/command/UnknownRequestException.java

@@ -0,0 +1,14 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.network.command;
+
+public class UnknownRequestException extends RuntimeException {
+    private final String requestName;
+
+    public UnknownRequestException(String message, String requestName) {
+        super(message);
+        this.requestName = requestName;
+    }
+
+    public String getRequestName() {
+        return requestName;
+    }
+}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/parser/PrimitiveRequest.java

@@ -3,4 +3,5 @@ package ch.unibas.dmi.dbis.cs108.casono.server.network.parser;
 import java.util.List;
 
 /** Created by the ProtocolParser to allow easy access to the request contents */
-public record PrimitiveRequest(int requestId, String command, List<Parameter> parameters) {}
+public record PrimitiveRequest(
+        RequestContext context, String command, List<Parameter> parameters) {}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/parser/ProtocolParser.java

@@ -1,6 +1,5 @@
 package ch.unibas.dmi.dbis.cs108.casono.server.network.parser;
 
-import ch.unibas.dmi.dbis.cs108.casono.server.network.transport.RawPacket;
 import ch.unibas.dmi.dbis.cs108.casono.server.tokenizer.RawToken;
 import ch.unibas.dmi.dbis.cs108.casono.server.tokenizer.Token;
 import ch.unibas.dmi.dbis.cs108.casono.server.tokenizer.TokenClassifier;
@@ -19,15 +18,15 @@ public class ProtocolParser {
      * @param packet the RawPacket containing the recieved data
      * @return created PrimitiveRequest
      */
-    public static PrimitiveRequest parse(RawPacket packet) {
-        List<RawToken> rawTokens = Tokenizer.tokenize(packet.payload());
+    public static RawRequest parse(String payload) {
+        List<RawToken> rawTokens = Tokenizer.tokenize(payload);
         List<Token> tokens = TokenClassifier.classify(rawTokens);
 
         Iterator<Token> iterator = tokens.iterator();
         String command = readCommand(iterator);
         List<Parameter> parameters = readParameters(iterator);
 
-        return new PrimitiveRequest(packet.requestId(), command, parameters);
+        return new RawRequest(command, parameters);
     }
 
     /**

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/parser/RawRequest.java

@@ -0,0 +1,5 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.network.parser;
+
+import java.util.List;
+
+public record RawRequest(String command, List<Parameter> parameters) {}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/parser/Request.java

@@ -1,4 +1,24 @@
 package ch.unibas.dmi.dbis.cs108.casono.server.network.parser;
 
+import ch.unibas.dmi.dbis.cs108.casono.server.network.sessions.SessionId;
+
 /** Request, produced by the CommandParser */
-public interface Request {}
+public abstract class Request {
+    protected final RequestContext context;
+
+    public Request(RequestContext context) {
+        this.context = context;
+    }
+
+    public RequestContext getContext() {
+        return context;
+    }
+
+    public SessionId getSessionId() {
+        return context.sessionId();
+    }
+
+    public int getRequestId() {
+        return context.requestId();
+    }
+}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/parser/RequestContext.java

@@ -0,0 +1,14 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.network.parser;
+
+import ch.unibas.dmi.dbis.cs108.casono.server.network.sessions.SessionId;
+
+/**
+ * Immutable context for a network request.
+ *
+ * <p>Contains the originating session's identifier and the request's id. Later used to create
+ * response.
+ *
+ * @param sessionId the identifier of the session that initiated the request
+ * @param requestId the request's numeric id within the session
+ */
+public record RequestContext(SessionId sessionId, int requestId) {}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/response/ErrorResponse.java

@@ -0,0 +1,34 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.network.response;
+
+import ch.unibas.dmi.dbis.cs108.casono.server.network.sessions.SessionId;
+
+/** Response representing an error outcome for a client's request. */
+public class ErrorResponse extends Response {
+    /**
+     * Construct an error response with a code and message.
+     *
+     * @param sessionId the target session id
+     * @param requestId the originating request id
+     * @param errorCode a short error code identifying the failure
+     * @param errorMessage a human readable error message
+     */
+    public ErrorResponse(
+            SessionId sessionId, int requestId, String errorCode, String errorMessage) {
+        super(
+                sessionId,
+                requestId,
+                ResponseBody.builder().param("CODE", errorCode).param("MSG", errorMessage).build());
+    }
+
+    /**
+     * {@inheritDoc}
+     *
+     * <p>This implementation returns the fixed {@code -ERR} prefix.
+     *
+     * @return the {@code -ERR} prefix
+     */
+    @Override
+    public String prefix() {
+        return "-ERR";
+    }
+}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/response/OkResponse.java

@@ -0,0 +1,20 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.network.response;
+
+import ch.unibas.dmi.dbis.cs108.casono.server.network.sessions.SessionId;
+
+/**
+ * A simple success response with an empty body.
+ *
+ * <p>Use this to acknowledge successful requests that do not carry additional payload data.
+ */
+public class OkResponse extends SuccessResponse {
+    /**
+     * Create a minimal successful response (no body content).
+     *
+     * @param sessionId the target session id
+     * @param requestId the originating request id
+     */
+    public OkResponse(SessionId sessionId, int requestId) {
+        super(sessionId, requestId, ResponseBody.builder().build());
+    }
+}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/response/PrimitiveResponse.java

@@ -2,4 +2,11 @@ package ch.unibas.dmi.dbis.cs108.casono.server.network.response;
 
 import ch.unibas.dmi.dbis.cs108.casono.server.network.sessions.SessionId;
 
+/**
+ * Immutable transport record representing an encoded response ready for delivery to a session.
+ *
+ * @param sessionId the target session id
+ * @param requestId the originating request id
+ * @param payload the serialized response payload
+ */
 public record PrimitiveResponse(SessionId sessionId, int requestId, String payload) {}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/response/Response.java

@@ -0,0 +1,58 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.network.response;
+
+import ch.unibas.dmi.dbis.cs108.casono.server.network.sessions.SessionId;
+
+/** Abstract base class for all server responses sent to clients. */
+public abstract class Response {
+    private final SessionId sessionId;
+    private final int requestId;
+    private final ResponseBody body;
+
+    /**
+     * Create a new {@code Response}.
+     *
+     * @param sessionId the id of the session this response targets
+     * @param requestId the request identifier this response corresponds to
+     * @param body the structured response body
+     */
+    protected Response(SessionId sessionId, int requestId, ResponseBody body) {
+        this.sessionId = sessionId;
+        this.requestId = requestId;
+        this.body = body;
+    }
+
+    /**
+     * Returns the protocol prefix for this response (for example {@code "+OK"} or {@code "-ERR"}).
+     *
+     * @return the response prefix string used by the encoder
+     */
+    public abstract String prefix();
+
+    /**
+     * Returns the session id that should receive this response.
+     *
+     * @return the target {@link SessionId}
+     */
+    public SessionId getSessionId() {
+        return sessionId;
+    }
+
+    /**
+     * Returns the request identifier associated with this response.
+     *
+     * @return the numeric request id
+     */
+    public int getRequestId() {
+        return requestId;
+    }
+
+    /**
+     * Returns the immutable {@link ResponseBody} that carries the structured payload for this
+     * response.
+     *
+     * @return the response body
+     */
+    public ResponseBody getBody() {
+        return body;
+    }
+}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/response/ResponseBlock.java

@@ -0,0 +1,12 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.network.response;
+
+import java.util.List;
+
+/**
+ * A block node that contains a tag and a list of child {@link ResponseNode} elements. Blocks can be
+ * nested to build hierarchical response bodies.
+ *
+ * @param tag the block tag
+ * @param children the child nodes contained in this block
+ */
+public record ResponseBlock(String tag, List<ResponseNode> children) implements ResponseNode {}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/response/ResponseBody.java

@@ -0,0 +1,40 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.network.response;
+
+import java.util.List;
+
+/**
+ * Immutable container for the structured content of a {@link Response}.
+ *
+ * <p>A {@code ResponseBody} holds an ordered list of {@link ResponseNode} items (parameters and
+ * blocks). Use {@link #builder()} to construct instances.
+ */
+public class ResponseBody {
+    private final List<ResponseNode> nodes;
+
+    /**
+     * Package-private constructor used by {@link ResponseBodyBuilder}.
+     *
+     * @param nodes the list of response nodes to include in this body
+     */
+    ResponseBody(List<ResponseNode> nodes) {
+        this.nodes = List.copyOf(nodes);
+    }
+
+    /**
+     * Create a new {@link ResponseBodyBuilder} for assembling a response body.
+     *
+     * @return a fresh builder instance
+     */
+    public static ResponseBodyBuilder builder() {
+        return new ResponseBodyBuilder();
+    }
+
+    /**
+     * Returns the ordered list of {@link ResponseNode} elements contained in this body.
+     *
+     * @return an immutable list of nodes
+     */
+    public List<ResponseNode> nodes() {
+        return nodes;
+    }
+}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/response/ResponseBodyBuilder.java

@@ -0,0 +1,51 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.network.response;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.function.Consumer;
+
+/**
+ * Builder for {@link ResponseBody} instances.
+ *
+ * <p>Provides methods to append parameter nodes and nested blocks and to produce an immutable
+ * {@link ResponseBody} via {@link #build()}.
+ */
+public class ResponseBodyBuilder {
+    private final List<ResponseNode> nodes = new ArrayList<>();
+
+    /**
+     * Add a key/value parameter to the response body under construction.
+     *
+     * @param key the parameter name
+     * @param value the parameter value (will be converted to string when encoded)
+     * @return this builder for fluent chaining
+     */
+    public ResponseBodyBuilder param(String key, Object value) {
+        nodes.add(new ResponseParameter(key, value));
+        return this;
+    }
+
+    /**
+     * Add a nested block with the given tag. The provided consumer receives a child builder to
+     * populate the block content.
+     *
+     * @param tag the block tag
+     * @param content consumer that appends child nodes to the block
+     * @return this builder for fluent chaining
+     */
+    public ResponseBodyBuilder block(String tag, Consumer<ResponseBodyBuilder> content) {
+        ResponseBodyBuilder childBuilder = new ResponseBodyBuilder();
+        content.accept(childBuilder);
+        nodes.add(new ResponseBlock(tag, childBuilder.build().nodes()));
+        return this;
+    }
+
+    /**
+     * Build an immutable {@link ResponseBody} from the accumulated nodes.
+     *
+     * @return a new {@link ResponseBody}
+     */
+    public ResponseBody build() {
+        return new ResponseBody(nodes);
+    }
+}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/response/ResponseDispatcher.java

@@ -0,0 +1,36 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.network.response;
+
+import ch.unibas.dmi.dbis.cs108.casono.server.network.sessions.Session;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.sessions.SessionManager;
+
+/**
+ * Helper that dispatches {@link Response} instances to the corresponding {@link Session} by
+ * encoding them and enqueuing the resulting {@link PrimitiveResponse} into the session's response
+ * queue.
+ */
+public class ResponseDispatcher {
+    private final SessionManager sessionManager;
+
+    /**
+     * Create a dispatcher bound to a {@link SessionManager}.
+     *
+     * @param sessionManager manager used to resolve sessions
+     */
+    public ResponseDispatcher(SessionManager sessionManager) {
+        this.sessionManager = sessionManager;
+    }
+
+    /**
+     * Encode the given {@link Response} and enqueue the resulting {@link PrimitiveResponse} into
+     * the target session's response queue.
+     *
+     * @param response the response to dispatch
+     * @throws InterruptedException if the thread is interrupted while waiting to enqueue the
+     *     primitive response
+     */
+    public void dispatch(Response response) throws InterruptedException {
+        PrimitiveResponse primitiveResponse = ResponseEncoder.encode(response);
+        Session session = sessionManager.getSessionById(response.getSessionId());
+        session.getResponseQueue().put(primitiveResponse);
+    }
+}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/response/ResponseEncoder.java

@@ -0,0 +1,98 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.network.response;
+
+/**
+ * Utility responsible for encoding a {@link Response} into a protocol payload string and wrapping
+ * it into a {@link PrimitiveResponse} suitable for transmission.
+ */
+public class ResponseEncoder {
+    private static final String INDENT = "\t";
+    private static final String NEWLINE = "\n";
+
+    /**
+     * Encode a {@link Response} into a {@link PrimitiveResponse} containing the serialized payload
+     * string.
+     *
+     * @param response the response to encode
+     * @return a {@link PrimitiveResponse} with encoded payload
+     */
+    public static PrimitiveResponse encode(Response response) {
+        StringBuilder sb = new StringBuilder();
+        sb.append(response.prefix());
+
+        for (ResponseNode node : response.getBody().nodes()) {
+            sb.append(NEWLINE);
+            encodeNode(node, sb, 1);
+        }
+
+        sb.append(NEWLINE).append("END");
+
+        return new PrimitiveResponse(
+                response.getSessionId(), response.getRequestId(), sb.toString());
+    }
+
+    /**
+     * Internal helper to encode any {@link ResponseNode}.
+     *
+     * @param node node to encode
+     * @param sb string builder to append to
+     * @param depth current indentation depth
+     */
+    private static void encodeNode(ResponseNode node, StringBuilder sb, int depth) {
+        if (node instanceof ResponseParameter param) {
+            encodeParameter(param, sb, depth);
+        } else if (node instanceof ResponseBlock block) {
+            encodeBlock(block, sb, depth);
+        }
+    }
+
+    /**
+     * Encode a {@link ResponseParameter} into the string builder.
+     *
+     * @param param the parameter to encode
+     * @param sb the output builder
+     * @param depth indentation depth
+     */
+    private static void encodeParameter(ResponseParameter param, StringBuilder sb, int depth) {
+        sb.append(INDENT.repeat(depth));
+        sb.append(param.key());
+        sb.append("=");
+        sb.append(maskIfNeeded(param.value().toString()));
+    }
+
+    /**
+     * Encode a {@link ResponseBlock}, including its children and terminating with an {@code END}
+     * marker.
+     *
+     * @param block the block to encode
+     * @param sb the output builder
+     * @param depth current indentation depth
+     */
+    private static void encodeBlock(ResponseBlock block, StringBuilder sb, int depth) {
+        sb.append(INDENT.repeat(depth));
+        sb.append(block.tag());
+
+        for (ResponseNode child : block.children()) {
+            sb.append(NEWLINE);
+            encodeNode(child, sb, depth + 1);
+        }
+
+        sb.append(NEWLINE);
+        sb.append(INDENT.repeat(depth));
+        sb.append("END");
+    }
+
+    /**
+     * Quote or escape the provided value if it contains whitespace or single quotes so the encoded
+     * payload remains parseable.
+     *
+     * @param value the raw string value
+     * @return quoted/escaped value
+     */
+    private static String maskIfNeeded(String value) {
+        if (value.contains(" ") || value.contains("'")) {
+            String escaped = value.replace("'", "\\'");
+            return "'" + escaped + "'";
+        }
+        return value;
+    }
+}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/response/ResponseNode.java

@@ -0,0 +1,8 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.network.response;
+
+/**
+ * Marker interface for elements that may appear in a {@link ResponseBody}.
+ *
+ * <p>Implementations include {@link ResponseParameter} and {@link ResponseBlock}.
+ */
+public interface ResponseNode {}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/response/ResponseParameter.java

@@ -0,0 +1,23 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.network.response;
+
+/**
+ * A parameter node stored in a {@link ResponseBody}.
+ *
+ * <p>Represents a simple key/value pair. Callers can use {@link #rawValue()} to obtain the string
+ * representation of the stored value.
+ *
+ * @param key the parameter name
+ * @param value the parameter value
+ */
+public record ResponseParameter(String key, Object value) implements ResponseNode {
+    /**
+     * Returns the raw string representation of the stored value. This is a convenience wrapper
+     * around {@code Object#toString()} and may throw {@link NullPointerException} if the stored
+     * value is {@code null}.
+     *
+     * @return the value as string
+     */
+    public String rawValue() {
+        return value.toString();
+    }
+}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/response/SuccessResponse.java

@@ -0,0 +1,34 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.network.response;
+
+import ch.unibas.dmi.dbis.cs108.casono.server.network.sessions.SessionId;
+
+/**
+ * Abstract {@link Response} specialization indicating a successful outcome.
+ *
+ * <p>Implementations of this class use the {@code +OK} prefix. It provides a protected constructor
+ * so subclasses can supply the response body content.
+ */
+public abstract class SuccessResponse extends Response {
+    /**
+     * Create a successful response with the provided body.
+     *
+     * @param sessionId the session id this response targets
+     * @param requestId the originating request id
+     * @param body the response body
+     */
+    protected SuccessResponse(SessionId sessionId, int requestId, ResponseBody body) {
+        super(sessionId, requestId, body);
+    }
+
+    /**
+     * {@inheritDoc}
+     *
+     * <p>This implementation returns the fixed {@code +OK} prefix.
+     *
+     * @return the {@code +OK} prefix
+     */
+    @Override
+    public final String prefix() {
+        return "+OK";
+    }
+}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/sessions/Session.java

@@ -1,6 +1,8 @@
 package ch.unibas.dmi.dbis.cs108.casono.server.network.sessions;
 
+import ch.unibas.dmi.dbis.cs108.casono.server.network.command.CommandRouter;
 import ch.unibas.dmi.dbis.cs108.casono.server.network.events.EventBus;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.parser.CommandParserDispatcher;
 import ch.unibas.dmi.dbis.cs108.casono.server.network.response.PrimitiveResponse;
 import ch.unibas.dmi.dbis.cs108.casono.server.network.transport.TransportLayer;
 import java.io.IOException;
@@ -12,6 +14,8 @@ public class Session {
     private final SessionId id;
     private final TransportLayer transport;
     private final BlockingQueue<PrimitiveResponse> responseQueue;
+    private final CommandParserDispatcher dispatcher;
+    private final CommandRouter router;
     private static final int RESPOND_QUEUE_SIZE = 32;
 
     /**
@@ -21,9 +25,15 @@ public class Session {
      * @param eventBus the event bus for publishing events
      * @throws IOException if an I/O error occurs during initialization
      */
-    public Session(TransportLayer transport, EventBus eventBus) {
+    public Session(
+            TransportLayer transport,
+            EventBus eventBus,
+            CommandParserDispatcher dispatcher,
+            CommandRouter router) {
         this.id = new SessionId();
         this.transport = transport;
+        this.dispatcher = dispatcher;
+        this.router = router;
         this.responseQueue = new ArrayBlockingQueue<>(RESPOND_QUEUE_SIZE);
     }
 
@@ -53,4 +63,17 @@ public class Session {
     public BlockingQueue<PrimitiveResponse> getResponseQueue() {
         return responseQueue;
     }
+
+    /**
+     * Returns the CommandParserDispatcher of this session
+     *
+     * @return the dispatcher to dispatch PrimitiveRequests to for parsing
+     */
+    public CommandParserDispatcher getDispatcher() {
+        return dispatcher;
+    }
+
+    public CommandRouter getRouter() {
+        return router;
+    }
 }

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/sessions/SessionManager.java

@@ -1,7 +1,9 @@
 package ch.unibas.dmi.dbis.cs108.casono.server.network.sessions;
 
+import ch.unibas.dmi.dbis.cs108.casono.server.network.command.CommandRouter;
 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.parser.CommandParserDispatcher;
 import ch.unibas.dmi.dbis.cs108.casono.server.network.transport.TransportLayer;
 import java.io.IOException;
 import java.util.Map;
@@ -14,12 +16,17 @@ public class SessionManager {
     private Map<SessionId, SessionHandle> sessions;
     private final EventBus eventBus;
     private final Logger logger;
+    private final CommandParserDispatcher dispatcher;
+    private final CommandRouter router;
 
     /** Constructs a new SessionManager. */
-    public SessionManager(EventBus eventBus) {
+    public SessionManager(
+            EventBus eventBus, CommandParserDispatcher dispatcher, CommandRouter router) {
         this.sessions = new ConcurrentHashMap<>();
         this.eventBus = eventBus;
         this.logger = LogManager.getLogger(SessionManager.class);
+        this.dispatcher = dispatcher;
+        this.router = router;
     }
 
     /**
@@ -31,14 +38,16 @@ public class SessionManager {
      * @return newly created session
      */
     public Session create(TransportLayer transport) {
-        Session session = new Session(transport, eventBus);
+        Session session = new Session(transport, eventBus, dispatcher, router);
         SessionReader reader = new SessionReader(session, eventBus);
         SessionWriter writer = new SessionWriter(session);
 
-        Thread readerThread = Thread.ofVirtual()
+        Thread readerThread =
+                Thread.ofVirtual()
                         .name("session-" + session.getId().value() + "-reader")
                         .unstarted(reader);
-        Thread writerThread = Thread.ofVirtual()
+        Thread writerThread =
+                Thread.ofVirtual()
                         .name("session-" + session.getId().value() + "-writer")
                         .unstarted(writer);
 

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/sessions/SessionReader.java

@@ -1,10 +1,15 @@
 package ch.unibas.dmi.dbis.cs108.casono.server.network.sessions;
 
+import ch.unibas.dmi.dbis.cs108.casono.server.network.command.CommandRouter;
 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.parser.CommandParserDispatcher;
 import ch.unibas.dmi.dbis.cs108.casono.server.network.parser.PrimitiveRequest;
 import ch.unibas.dmi.dbis.cs108.casono.server.network.parser.ProtocolParser;
 import ch.unibas.dmi.dbis.cs108.casono.server.network.parser.ProtocolParserException;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.parser.RawRequest;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.parser.Request;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.parser.RequestContext;
 import ch.unibas.dmi.dbis.cs108.casono.server.network.transport.RawPacket;
 import ch.unibas.dmi.dbis.cs108.casono.server.network.transport.TransportLayer;
 import ch.unibas.dmi.dbis.cs108.casono.server.tokenizer.TokenizerException;
@@ -17,12 +22,16 @@ public class SessionReader implements Runnable {
     private final Session session;
     private final TransportLayer transport;
     private final EventBus eventBus;
+    private final CommandParserDispatcher dispatcher;
+    private final CommandRouter router;
     private final Logger logger;
 
     public SessionReader(Session session, EventBus eventBus) {
         this.session = session;
         this.transport = session.getTransport();
         this.eventBus = eventBus;
+        this.dispatcher = session.getDispatcher();
+        this.router = session.getRouter();
         this.logger =
                 LogManager.getLogger(
                         SessionReader.class.toString() + "-" + session.getId().value());
@@ -36,8 +45,19 @@ public class SessionReader implements Runnable {
                 rawPacket = transport.read();
                 logger.debug("Recieved: {}", rawPacket);
 
-                PrimitiveRequest primitiveRequest = ProtocolParser.parse(rawPacket);
-                logger.debug("Parsed request to {}", primitiveRequest);
+                RawRequest rawRequest = ProtocolParser.parse(rawPacket.payload());
+                logger.debug("Parsed request to {}", rawRequest);
+
+                RequestContext requestContext =
+                        new RequestContext(session.getId(), rawPacket.requestId());
+                PrimitiveRequest primitiveRequest =
+                        new PrimitiveRequest(
+                                requestContext, rawRequest.command(), rawRequest.parameters());
+                logger.debug("Converted to {}", primitiveRequest);
+
+                Request request = dispatcher.parse(primitiveRequest);
+
+                router.execute(request);
             } catch (EOFException e) {
                 logger.info("Client disconnected");
                 eventBus.publish(new DisconnectEvent(session.getId()));