sockets.md

id	title
sockets	Socket Channel

AsynchronousSocketChannel and AsynchronousServerSocketChannel provide methods for communicating with remote clients.

Required imports for snippets:

import zio._
import zio.clock._
import zio.console._
import zio.nio.channels._
import zio.nio._

Creating sockets

Creating a server socket:

val server = AsynchronousServerSocketChannel.open
  .mapM { socket =>
    for {
      address <- InetSocketAddress.hostName("127.0.0.1", 1337)
      _ <- socket.bindTo(address)
      _ <- socket.accept.preallocate.flatMap(_.use(channel => doWork(channel).catchAll(ex => putStrLn(ex.getMessage))).fork).forever.fork
    } yield ()
  }.useForever

def doWork(channel: AsynchronousSocketChannel): ZIO[Console with Clock, Throwable, Unit] = {
  val process =
    for {
      chunk <- channel.readChunk(3)
      str = chunk.toArray.map(_.toChar).mkString
      _ <- putStrLn(s"received: [$str] [${chunk.length}]")
    } yield ()

  process.whenM(channel.isOpen).forever
}

Creating a client socket:

val clientM: Managed[Exception, AsynchronousSocketChannel] = AsynchronousSocketChannel.open
  .mapM { client =>
    for {
      host    <- InetAddress.localHost
      address <- InetSocketAddress.inetAddress(host, 2552)
      _       <- client.connect(address)
    } yield client
  }

Reading and writing to a socket:

for {
  serverFiber <- server.fork
  _ <- clientM.use(_.writeChunk(Chunk.fromArray(Array(1, 2, 3).map(_.toByte))))
  _           <- serverFiber.join
} yield ()