NetCode Transport for MultipeerConnectivity

Overview

This package implemented the transport layer of Netcode for GameObjects with Apple Multipeer Connectivity, which can enable peer-to-peer communication between nearby devices. By using Multipeer Connectivity, nearby devices can connect to each other when there is no WiFi or cellular network. Multipeer Connectivity is the technology behind AirDrop, which means it can transfer large file between devices very fast. Please reference Apple's official document for detailed information: https://developer.apple.com/documentation/multipeerconnectivity.

We created a sample project demonstrating how to properly setup the network connection.

We contribute this package to Unity Multiplayer Community repo. See https://github.com/Unity-Technologies/multiplayer-community-contributions/tree/main/Transports/com.community.netcode.transport.multipeer-connectivity

How To Install

This package uses the scoped registry feature to resolve package dependencies. Open the Package Manager page in the Project Settings window and add the following entry to the Scoped Registries list:

• Name: Reality Design Lab
• URL: https://registry.npmjs.com
• Scope: org.realitydeslab

Now you can Install a package from a registry by name:

org.realitydeslab.netcode.transport.multipeer-connectivity

Some Good to Know Concepts Before Using The Transport

• Host-Client Architecture vs Peer-To-Peer Architecture

Before using this transport, it is important to know that Netcode for GameObjects uses a host-client network architecture while Multipeer Connectivity uses a peer-to-peer architecture.

In a host-client network, one device hosts the network and other devices join the network as clients. The host can directly communicate with all connected clients but a client can only directly communicate with the host. For two connected client, the messages they send to each other must be relayed by the host.

In a peer-to-peer network, there is no host device and any two devices are connected directly as peers. Therefore, any two peers can directly send messages to each other.

In this transport, we wrapped Multipeer Connectivity in a host-client manner to fit the architecture of Netcode for GameObjects.

• Advertising and Browsing

Before nearby devices can establish network connection, Multipeer Connectivity requires a discovery phase where nearby devices first find each other. This makes Multipeer Connectivity transport different from other Netcode transports.

In Multipeer Connectivity, an advertiser is a device which advertises itself and a browser is a device which browses nearby advertising peers. Therefore, in discovery phase, the host device should be an advertiser and all other devices should be browsers. In the following sections, we will use host and advertiser, client and browser interchangeably.

When a host starts the network, it starts to advertise itself so that nearby browsers can find it. When a browser finds a nearby host (an advertiser), it sends a connection request to the host. If the host approves the connection request, the sender of the connection request will be connected to the network as a client. When a client successfully connects to the network, it should stop browsing.

For more details, visit the GitHub repository above.