NIO Hello World

helloworld.swift

import Foundation
import NIO
import NIOHTTP1

// Inspired/parts copied from http://www.alwaysrightinstitute.com/microexpress-nio/

final class HelloHandler: ChannelInboundHandler {
    typealias InboundIn = HTTPServerRequestPart
    
    func channelRead(ctx: ChannelHandlerContext, data: NIOAny) {
        let reqPart = unwrapInboundIn(data)
        switch reqPart {
        case .head(let header):
            let head = HTTPResponseHead(version: header.version, status: .ok)
            let part = HTTPServerResponsePart.head(head)
            _ = ctx.channel.write(part)
            let responseStr = "Hello, world"
            var buffer = ctx.channel.allocator.buffer(capacity: responseStr.utf8.count)
            buffer.write(string: responseStr)
            let bodyPart = HTTPServerResponsePart.body(.byteBuffer(buffer))
            _ = ctx.channel.write(bodyPart)
            _ = ctx.channel.writeAndFlush(HTTPServerResponsePart.end(nil)).then {
                ctx.channel.close()
            }
        case .body, .end:
            break
        }
    }
}

struct MyServer {
    let group = MultiThreadedEventLoopGroup(numThreads: System.coreCount)
    
    func listen(port: Int = 8765) throws {
        let reuseAddr = ChannelOptions.socket(SocketOptionLevel(SOL_SOCKET),
                                              SO_REUSEADDR)
        let bootstrap = ServerBootstrap(group: group)
            .serverChannelOption(ChannelOptions.backlog, value: 256)
            .serverChannelOption(reuseAddr, value: 1)
            .childChannelInitializer { channel in
                channel.pipeline.configureHTTPServerPipeline(withErrorHandling: true).then {
                    channel.pipeline.add(handler: HelloHandler())
                }
            }
            .childChannelOption(ChannelOptions.socket(
                IPPROTO_TCP, TCP_NODELAY), value: 1)
            .childChannelOption(reuseAddr, value: 1)
            .childChannelOption(ChannelOptions.maxMessagesPerRead,
                                value: 1)
    
        let channel = try bootstrap.bind(host: "localhost", port: port).wait()
        try channel.closeFuture.wait()
    }
}

let s = MyServer()
try s.listen()