Open Match

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Open Match

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Overview

👀 Overview

Open Match is an open-source game matchmaking framework that simplifies building a scalable and extensible Matchmaker. It is designed to give the game developer full control over how to make matches while removing the burden of dealing with the challenges of running a production service at scale.

📄 Open Match Concepts

Ticket

A basic matchmaking entity in Open Match that represents a player (or group of players) requesting a match.

Assignment

A mapping from a game server assignment to a Ticket.

Match

A collection of Tickets and some metadata of a match.

📝 Components users need to implement

Match Function(MMF)

The core matchmaking logic is implemented as a service. It is invoked by Open Match to generate matches. It takes lists of tickets (which meet certain constraints) as input and returns any number of Matches. For this basic demo, the Match Function simply pairs any two players into a Match.

Director

A component that requests Open Match for matches and then sets Assignments on the Tickets in the matches found.

Client

A service that translates in-queued players into Tickets in Open Match understandable language - instructs Open Match a player is currently looking for a match.

🌊 General Matchmaking Flow

Matchmaking using Open Match

🗺 Architecture

🌟 Open Match Core

Open Match comprises of a set of services hosted in a Kubernetes cluster. These services expose the core functionality of Open Match over gRPC and HTTP

Open Match FrontendService

The Open Match FrontendService is used to create, delete and get details of the current state of a Ticket. The Open Match FrontendService is used to create, delete and get details of the current state of a Ticket.

Open Match BackendService

The Open Match BackendService is used to generate Matches and create Assignments for the Matches when invoked by the Director, and returning Assignments to the Open Match Frontend when requested.

**Open Match QueryService

The QueryService enables querying the Tickets that meet certain constraints from the current Ticket pool.

🧩 **Customized Components

To build a custom Matchmaker using Open Match, the user needs to provide the following customizations. These can be authored as services exposed over gRPC or HTTP endpoints.

Match Function

The core matchmaking logic is implemented as a Match Function service. Open Match Backend triggers the Match Function service when it receives a request to generate Matches. The Match Function execution receives MatchProfiles, fetches Tickets that match the profile from QueryService, and returns Matches.

Match Function

**Evaluator (Optional)

Open Match allows for concurrent Match Functions to execute on the same player pool. The Matches generated by such concurrent Match Function executions may have overlapping Tickets. Given that one Ticket should only be used by one resulting Match, Open Match allows the user to plug in an Evaluator component to deduplicate Match proposals before returning results. Open Match provides a default Evaluator which suffices for most common use cases. See the Evaluator Guide for details on proposal evaluation.

Evaluator and Synchronizer

📥 **External Components

Although Open Match based Matchmaker offers core matchmaking functionality, other Game Services will be needed to handle key features such as handling player connections, fetching DGS (Dedicated Game Server) allocations, etc. These services interact with Open Match to enable game-specific matchmaking scenarios. Here is an overview of these services that are external to an Open Match based Matchmaker but are a part of an end-to-end setup:

**Game Frontend

This component receives the matchmaking request from the game client and eventually provides the game client with the Assignment. The Game Frontend typically authenticates the player, fetches player data and creates a matchmaking request in Open Match, and fetches the Assignment for the Ticket.

Game Frontend

• Game Front End On Creating a Ticket

  sequenceDiagram
  title Create Ticket
  
  participant Game Client
  participant Game Backend
  participant OpenMatch Frontend
  participant Redis
  
  Game Client->>Game Backend:request Matchmaking
  note over Game Backend:get player data
  Game Backend->>OpenMatch Frontend:request CreateTicket with player data inserted
  note over OpenMatch Frontend:generate ticket
  OpenMatch Frontend->>Redis:store ticket
  OpenMatch Frontend-->>Game Backend:return Ticket
  Game Backend-->>Game Client:return Ticket
  

• Game Front End On Connecting player to Game Server

  sequenceDiagram
  title Connect to GameServer
  
  participant Game Server
  participant Game Client
  participant Game Backend
  participant OpenMatch Frontend
  
  Game Client->>Game Backend:request Matchmaking
  note over Game Backend:get player data
  Game Backend->>OpenMatch Frontend:request CreateTicket with player data inserted
  note over OpenMatch Frontend:generate ticket
  OpenMatch Frontend-->>Game Backend:return Ticket
  Game Backend-->>Game Client:return Ticket
  
  loop check ticket
  	Game Client->>Game Backend:request GetTicket
  	Game Backend->>OpenMatch Frontend:request GetTicket
  	OpenMatch Frontend-->>Game Backend:return Ticket
  	Game Backend-->>Game Client:return Ticket
  	note over Game Client:check if ticket assigned
  end
  alt ticket assigned
  	Game Client->>Game Server:connect to gameserver
  end
  

Director

This is the component that understands the types of matches (MatchProfiles) that can be served and fetches matches from the Open Match Backend. The Director also interfaces with the DGS allocation system to fetch Game Servers for Matches and create Game Server Assignments from these details in Open Match, via communicating with the Open Match Backend.

Director

• Director On Creating a Match

  sequenceDiagram
  title Create Match
  
  participant Director
  participant OpenMatch Backend
  participant Match Function
  participant OpenMatch Query
  participant Redis
  
  note over Director:generate match profile
  Director->>OpenMatch Backend:call FetchMatches with MatchProfile
  OpenMatch Backend->>Match Function:execute Run with MatchProfile
  Match Function->>OpenMatch Query:call QueryTickets with MatchProfile
  OpenMatch Query->>Redis:query tickets based on MatchProfile
  Redis-->>OpenMatch Query:return Tickets
  OpenMatch Query-->>Match Function:return Tickets
  note over Match Function:run matchmaking logic and generate matches
  Match Function-->>OpenMatch Backend:return Matches
  alt matches found
  	note over OpenMatch Backend:set the matches tickets to "pending" state
  	OpenMatch Backend-->>Director:return Matches
  	note over Director:request gameserver allocation
  	Director->>OpenMatch Backend:call AssignTickets with allocated gameserver address
  	OpenMatch Backend-->>Director:return Assignment result
  end
  

• Director on Game Server Allocation

  sequenceDiagram
  title GameServer Allocation
  
  participant Agones
  participant Director
  participant OpenMatch Backend
  
  loop
  	Director->>Agones:get gameserver list
  	Agones-->>Director:return gameserver list
  	note over Director:query for available gameserver
  	alt gameserver available
  		note over Director:generate MatchProfile
  		Director->>OpenMatch Backend:call FetchMatches with MatchProfile
  		note over OpenMatch Backend:execute Run in Match Function
  		OpenMatch Backend-->>Director:return Matches
  		alt match found
  			Director->>Agones:allocate gameserver
  			Agones-->>Director:return gameserver info
  			Director->>OpenMatch Backend:call AssignTickets with allocated gameserver address
  			OpenMatch Backend-->>Director:return Assignment result
  		end
  	end
  end