Azure PlayFab Relay

PlayFab is a backend platform for building and operating live games. It provides a suite of managed game services, real-time analytics, and LiveOps tools within a single platform. It provides a free service as well as pay-per-month plans. In order to use PlayFab you'll need to set up a game with a valid PlayFab Title ID. Once you have a PlayFab Title ID, you'll be able to pass messages between clients via PlayFab's servers.

To make things easy, coherence provides a complete PlayFab relay implementation that provides out-of-the-box networking over PlayFab. The PlayFab relay utilizes the PlayFabPartyUnity package to access the PlayFab Party API.

The PlayFab Integration is using a combination of the PlayFab relay servers and an implementation of ICoherenceRelay to enable PlayFab users to connect and play with each other while avoiding NAT issues. The ICoherenceRelay implementation allows for users to connect to the hosting client through PlayFab, and have the client forward their data packets to the user-hosted Replication Server.

The sample code in the repository demonstrates how to join and host a game with the PlayFab Party API.

The Azure PlayFab relay is available here: https://github.com/coherence/playfab-integration-sample

PlayFab relay overview

Connecting over PlayFab, step-by-step

1. The host (Client A) initializes the PlayFabClientAPI that handles PlayFab connections and then starts a Replication Server on its local machine.

2. The host connects to the local Replication Server and joins the PlayFab network. The host receives the remote server's network ID and host id. These are used by clients to connect to PlayFab's services.

3. Another player (Client B) connects to the host via PlayFab using the PlayFabTransport.

4. The PlayFabRelay accepts the incoming connection, creating a PlayFabRelayConnection.

5. The PlayFabRelayConnection immediately starts passing data between the PlayFab servers and the Replication Server.

6. The relayed connection is now fully established. All data between Client B and the Replication Server is relayed through PlayFab.

7. For each new Client that connects, steps 3-6 are repeated.

Although the diagram above shows that traffic is routed via PlayFab servers, it is often the case that traffic can flow directly between player and host machines without actually making the extra hop via the PlayFab servers. This technique is commonly referred to as "hole punching" or "NAT Punch-through" and greatly reduces latency, however, it is not supported on all networks due to firewall restrictions.

PlayFab Party will first attempt a NAT punch-through and then automatically fall back to relayed communication if the punch-through failed.