Game Server

This is a “simple” game server. Main functionalities are matching and establishing a connection between players

How to Run?

run the server first

go run ./cmd/server/server.go

and run as many client as you want (kidding, go easy 🙂 ).

go run ./cmd/client/client.go

Folder Structure and Packages:

Package Folder Description
server /server Server is main package of this project it contains the code for matching (TCP) and connection(UDP)
client /client Client is an abstract representation of player.
config /config Config package holds the server configurations such as connection information, game size etc.
frame /frame Frame package is a data frame package. It designed and developed just for this project and It is a serializer for a game events. A detailed frame information is in below. frame contains 3 section.first is the header, it holds the important information about this frame such as gameID, clientID and number of event.second section is events. Event is a basic information packets. it holds a eventID and a data part.last section is for time stamp.
simulator /simulator Simulator simulates a pseudo client events and it listens for certain events like game over.
test /simulator There is only one test in this project and it controls the frame marshal and unmarshal functions.
utils /utils utils has general utility functions and the most important part is encoding and decoding functions. they are crucial for frame package.
cmd /cmd cmd folder has 2 subfolder named server and client. Those packages can run by themselves to simulate a game server/client environment. there is a demonstration of client and server.

Frame in Detail

|                header              |                events...                |  time     |
|clientID | gameID | number of event | eventID  |  data | eventID  |  data |...| timeStamp |
|  2byte  | 2byte  |     1byte       |   1byte  | 4byte |   1byte  | 4byte |...|   8byte   |
|  16bit  | 16bit  |     8bit        |   8bit   | 32bit |   8bit   | 32bit |...|   64bit   |

Server and client communication demonstration

Server Work Flow

Game Matcher

Mather is using TCP connections to receive game requests.

After a game request has arrived matcher is adding that user to a queue. if there are enough participant in the queue, matcher groups them under a gameID and attaches this group to the gameList.

After adding group to the gameList it removes players from the gameQueue and closes their TCP connections.

*Game size can be change from /config directory.

Game Routine

Game routine listens UDP packets. First it needs a register request from client. And receives a response with gameID and clientID.

When register arrive game routine start to reads and process incoming data and send back to clients.

*Game routine is schedules a dummy game over routine to test if games are lasting properly. Max and min game times are configurable from /config directory.

Client Game Request

Client sends an initial message that contains a “token” if token is valid (and there are enough participant to create a game of course) server responds it with a gameID and clientID.

Client uses those information to send a initial UDP register message.

Client waits for game started event and send a pseudo random events to the server.

When game over event has arrived client ends its process.

*event sending and receiving functions are not serial functions. they are running concurrently

Flow charts


  • To avoid ip:port collision event, all clients opens their UDP listen port differently. for example client 3’s UDP port is 9093(9090+3)

  • There is also a dummy non-functional authentication system. it is like a placeholder for better authentication and authorization systems.

  • There is an easy interrupt handle for client and server. If client receives an interrupt (SIGINT, SIGTERN or SIGQUIT) it sends a disconnected event to server and server broadcasts a game over event to all players. Likewise If server interrupted it send the same game over event to all players in all games.