swift-server-engine.io

Engine.IO server implementation in Swift, built on top of Hummingbird.

This package provides:

• EngineIO: the server library
• EngineIOTestApp: a small echo server used for protocol testing

Status

The project currently focuses on Engine.IO transport behavior, including:

• HTTP long-polling
• WebSocket upgrades
• Engine.IO v4 packet encoding and decoding
• Protocol test-suite compatibility via Docker

Installation

Add the package dependency to your Package.swift:

.package(url: "https://github.com/thomasauger/swift-server-engine.io.git", exact: "4.0.0-beta.2")

Then depend on the EngineIO product:

.product(name: "EngineIO", package: "swift-server-engine.io")

Quick Start

import EngineIO

@main
struct App {
    static func main() async throws {
        let server = Server(
            port: 3000,
            configuration: .init(
                heartbeat: .init(
                    pingTimeout: .milliseconds(200),
                    pingInterval: .milliseconds(300)
                ),
                transport: .init(maxPayload: 1_000_000),
                lifecycle: .init(
                    onMessage: { connection, data in
                        await connection.send(data)
                    },
                    onError: { error in
                        print("Engine.IO error:", error.message)
                    }
                )
            )
        )

        try await server.run()
    }
}

The demo executable in Demo/EngineIO/App.swift uses the same setup.

If you want to embed Engine.IO into an existing Hummingbird app, use EngineIOEndpoint:

import EngineIO
import Hummingbird
import HummingbirdWebSocket

let endpoint = EngineIOEndpoint(configuration: .init())
let router = Router()
endpoint.install(into: router)

let app = Application(
    router: router,
    server: .http1WebSocketUpgrade(configuration: endpoint.webSocketConfiguration) { request, _, logger in
        await endpoint.shouldUpgrade(request: request, logger: logger)
    }
)

Development

Run the Swift test suite:

swift test

Run the Engine.IO protocol tests:

docker compose run --build --rm engine-test

Run both:

make test

References

• Engine.IO protocol repository: https://github.com/socketio/engine.io-protocol
• Socket.IO website: https://socket.io/