diff --git a/documents/docs/networking/server-architecture.md b/documents/docs/networking/server-architecture.md new file mode 100644 index 0000000..93ad908 --- /dev/null +++ b/documents/docs/networking/server-architecture.md @@ -0,0 +1,81 @@ +# Server-Side Networking — How It All Fits Together + +This doc is meant to give a solid mixed-level understanding of how our server-side networking works. No deep dives — just a clear picture of what's happening under the hood when a client connects and sends a command. + +> **Note:** This is v1. Annotations and Reflection-based dispatching are on the roadmap but not covered here yet. + +> **Disclamer:** This document has been written by Claude. I modified certain parts and verified its contents for correctness. + +## Our Protocol at a Glance + +Our protocol is inspired by **POP3** - a classic, text-based protocol that communicates over a raw TCP connection. The idea is simple: the client sends a command as a plain-text string, and the server responds with either a success or an error. + +A typical exchange looks something like this: + +``` +Client → GET_DELTA SINCE=42 +Server → +OK + PLAYER_FOLDED playerId=3 + POT 240 + NEXT_TURN playerId=1 + . +``` + +Responses start with `+OK` on success or `-ERR` when something goes wrong. Commands are short, uppercase strings - sometimes followed by arguments. + +We don't use HTTP, there's no JSON body, no headers. Just a raw socket, a text stream, and a clearly defined set of commands. + +## Core Components & Their Roles + +Here's a quick rundown of the main building blocks: + +### `NetworkManager` +This is the entry point. It binds to a specific port and listens for incoming TCP connections. +Once a client connects, it creates a `Session` adds it to the `SessionManager` and goes back to waiting. Its not the responsibility of the `NetworkManager` to recieve and send data from and to each connected client. + +### `Session` +Every client that connects has its own `Session` instance running on its own thread. This component owns the lifecycle of that connection: it reads incoming data, passes it along for processing, and writes responses back. + +### `SessionManager` +The `SessionManager` stores all currently active sessions. It allows for the retrieval of a specific session by its id. + +### `ProtocolParser` +Raw text (encapsulated in a `RawRequest`) coming off the socket isn't immediately useful — the `ProtocolParser` turns it with the help of the `Tokenizer` into a `PrimitiveRequest`. + +### `RawRequest` +The `RawRequest` object is created after a message has been recieved. +It holds both a reference to the `Session` that recieved the message and the message itself. + +### `PrimitiveRequest` +The `PrimitiveRequest` object is created by the `ProtocolParser` after the content of the `RawRequest` has been tokenized by the `Tokenizer`. +The command is stored in its own attribute and the arguments are accessible as a dictionary. + +### `Tokenizer` +The job of the `tokenizer` is it, to take the raw string and turn it into tokens. +For example, the command `CHAT_LOBBY GAME=12 MESSAGE='All-in?'` will be decoded as `"CHAT_LOBBY", "GAME", "=", "12", "MESSAGE", "=", "All-in?"`. +It is unaware about the meaning. + +### `CommandParser` (per command) +Takes in the `PrimitiveRequest` and checks if all required fields are provided with the correct value. +Creates a command specific `Request` object containing command arguments in a structured manner. + +### `Request` (per command) +Has fields common along each implementation such as a reference to the `Session` that recieved the request. +Furthermore each implementation has fields unique to each command. For example, the `ChatLobbyRequest` has fields for the game and the message. + +### `CommandRouter` +By identifying the type of class of the `Request`, the `CommandRouter` routes the request to the matching `CommandHandler`. + +### `CommandHandler` (per command) +Each supported command has its own handler — a small, focused class that contains the logic for that specific command. They have access to the domain, containing inner parts of the game itself. + +### `Response` (per response) +The interface has two sub-interfaces for either failed `ErrorResponse` or successfull `SuccessResponse` execution of commands. + +Each step has exactly one responsibility. Increasing the ability to test and extend different components later on. + +## Concurrency - Handling Multiple Clients + +Every incoming connection spawns a new **Thread**. This means multiple clients can be served simultaneously without blocking each other. + +As each `Session` runs entirely on its own thread, there's no shared mutable state between sessions, with exception of the `SessionManager` and other key components explained later.