comunication protocol

                  R-TYPE COMMUNICATION PROTOCOL

Abstract

This document provides an in depth specification of the client <-> server communication protocol implemented during the Epitech R-Type project. The protocol as described in this document contains all necessary commands a client must implement in order to participate in games run by the R-Type server.

Status of this Memo

This memo is the specification of the Communication Protocol implemented by its authors for the R-Type Epitech project. This specification is an exercise in the writing of an rfc document as defined by RFC 7322 "RFC Style Guide". This specification does not aim to be submitted at any point in time.

This document is not subject to any copyright notice and thus expresses no rights reserved.

Table of Contents

1. Introduction ...................................................X
2. TCP Protocol ...................................................X
    2.1. Command Syntax ...........................................X
    2.2. Command Response .........................................X
        2.2.1. Response Codes and Meaning .........................X
    2.3. Server Commands ..........................................X
    2.4. Client Commands ..........................................X
3. UDP Protocol ...................................................X
    3.1. Command Syntax ...........................................X
    3.2. Server Commands ..........................................X
        3.2.1. Server Command Listing .............................X
        3.2.2. Server Command Arguments ...........................X
    3.3. Client Commands ..........................................X
        3.3.1. Server Response ....................................X
        3.3.2. Client Command Listing .............................X
        3.3.3. Client Command Arguments ...........................X

Introduction
The R-Type project is an epitech project that aims to produce a multiplayer game based on the R-Type game.
This project aims to introduce students to the intricate details of building a networked multiplayer game while also focusing on the package the game is delivered in. This includes but is not limited to :
```
 - Crossplatform build system
 - Limited user setup required
 - Multithreaded server
 - Inability to cheat using modified client
```

TCP Protocol

The TCP protocol will serve as the main protocol used by the client and server before the start of a game. It will also serve the purpose of handling anything non relevent to the game currently being played. The sole exception to that last bit will be the handling of in game messaging and server message broadcasting.

2.1. Command Syntax

 TCP commands follow the following syntax :

         <CMD> <SP> <HEADER>;<ARGS> <CRLF>

 Here is a definition of each part :

 <CMD>    -> This is the command name and will always be fully
             capitalized.

 <SP>     -> Ascii space character

 <HEADER> -> For client commands, user UUID. For server commands,
             server UUID. Both distributed by server on
             connection.
 
 <ARGS>   -> Arguments for given command. These args are
             separated by the ',' ascii character.

 <CRLF>   -> Carriage Return Line Feed character. Every message
             will end in this character combination denoted
             '\r\n' in ascii.

2.2. Command Response

 All client sent commands will generate a response from the
 server allowing the client to know the status of their command.

 Responses will follow the following syntax :

         <CODE> <SP> <HEADER> <SP> <BODY> <CRLF>

 In this format, the HEADER is the server's UUID, that the client
 can use in order to make sure he is interacting with the correct
 server.

 The response format is similar to the command synthaxe, except
 that the cmd is replaced by a three digit response code that
 mimics that of the HTTP protocol.

 2.2.1. Response Codes and Meanings

     The following is a list of all possible response code. This
     list of response codes is strongly inspired by the response
     codes of the HTTP protocol.

         - 500 -> Wrong Request
         - 401 -> Forbidden
         - 200 -> OK

2.3. Server Commands

 The only server command that currently needs any handling by the
 client is the START command.

 The START command will provide one argument, which is the port
 that the client should send his first UDP message to.

2.4. Client Commands

 The following is a list of Client Commands :

     - CONNECT -> Only command with no header. This command
                  allows the client to retrieve his user assigned
                  uuid.

     - START   -> This command allows the user to signal to the
                  server that the game should start.

UDP Protocol

The UDP protocol will be the main protocol used to communicated the behaviour of the game to clients during any given game.

Since in this project the server is supposed to handle most of the game logic this protocol will be centered around the ECS and communicating it's state over the course of a given game.

NO UDP SERVER COMMAND will await any type of response.

3.1. Command Synthax

 Commands follow the following syntax :

         <CMD> <SP> <ARGS> <CRLF>
 
 Here is a definition of each part :

 <CMD>  -> This is the command name and will always be fully
           capitalized.

 <SP>   -> Ascii space character

 <ARGS> -> These are the arguments for the command. The size of
           these args may vary even within the same command. For
           this purpose each argument will be separated by the
           ';' character.
           
           Any sub-argument within each argument will be
           separated by the ',' character.

 <CRLF> -> Carriage Return Line Feed character. Every message
           will end in this character combination denoted '\r\n'
           in ascii.
 
 Here is an example of a valid server command :

                      DEL_ENT 1 \r\n

3.2. Server Commands

 This section details the commands sent by the server to clients
 along with their usage.

 3.2.1 Server Command Listing

     The following is a listing of all valid server commands :

             ENTITY        ->    Provide entity description, with
                                 component args.
             DEL_ENT       ->    Delete entity
             DEL_COMP      ->    Delete component
             CHANGE_MUSIC  ->    Change Song
             GAME_END      ->    Signals end of game

 3.2.2. Server Command Arguments

     The following is an explanation of the arguments needed for
     each server command :

               <THIS LIST NEEDS ELABORATING>

     ENTITY ->
         (entity id, (component id, component args...)...)
     DEL_ENT -> (entity id)
     DEL_COMP -> (entity id, component id)
     MUSIC -> (song id)

3.3. Client Commands

 This section details the commands sent by the client to the
 server along with their arguments and usage.

 In contrast with Server Commands, some of these commands will
 elicit a response.

 3.3.1. Server Response

     The server response to client commands will always be in the
     form of server commands. This means and allows the client to
     not have to wait on the server response as the "server
     response" only needs to be handled like any other command.

 3.3.2. Client Command Listing

     These commands WILL illicit a response, this response will
     take the form of commands, so should not be waited for:

         HERE        ->      Signal connection to server
         GET_ENT     ->      Get specification for entity

     These commands WILL NOT illicit any response:

         ACT_SHOOT   ->      Signal the server that the client
                             shot.
         ACT_MOVE    ->      Signal the server that the client
                             has moved.
         PING        ->      Signal server that client is
                             still connected. Required every
                             three seconds.

 3.3.3. Client Command Arguments

     The following is a listing of the arguments for each client
     command.

         GET_ENT     ->      (entity id)
         ACT_SHOOT   ->      No arguments
         ACT_MOVE    ->      (direction)
         HERE        ->      (client UUID)

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