Source code for Akka IO http server example

HTTP.scala

/**
 * © 2012 Typesafe Inc.
 * 
 * Extracted from  http://doc.akka.io/docs/akka/2.1.0-RC2/scala/io.html
 */

import akka.actor._
import akka.util.{ ByteString, ByteStringBuilder }
import java.net.InetSocketAddress

object HttpConstants {
  val SP = ByteString(" ")
  val HT = ByteString("\t")
  val CRLF = ByteString("\r\n")
  val COLON = ByteString(":")
  val PERCENT = ByteString("%")
  val PATH = ByteString("/")
  val QUERY = ByteString("?")
}


case class Request(meth: String, path: List[String], query: Option[String], httpver: String, headers: List[Header], body: Option[ByteString])
case class Header(name: String, value: String)

object HttpIteratees {
  import HttpConstants._
 
  def readRequest =
    for {
      requestLine ← readRequestLine
      (meth, (path, query), httpver) = requestLine
      headers ← readHeaders
      body ← readBody(headers)
    } yield Request(meth, path, query, httpver, headers, body)

def ascii(bytes: ByteString): String = bytes.decodeString("US-ASCII").trim
 
def readRequestLine =
  for {
    meth ← IO takeUntil SP
    uri ← readRequestURI
    _ ← IO takeUntil SP // ignore the rest
    httpver ← IO takeUntil CRLF
  } yield (ascii(meth), uri, ascii(httpver))


def readRequestURI = IO peek 1 flatMap {
  case PATH ⇒
    for {
      path ← readPath
      query ← readQuery
    } yield (path, query)
  case _ ⇒ sys.error("Not Implemented")
}

def readPath = {
  def step(segments: List[String]): IO.Iteratee[List[String]] = IO peek 1 flatMap {
    case PATH ⇒ IO drop 1 flatMap (_ ⇒ readUriPart(pathchar) flatMap (segment ⇒ step(segment :: segments)))
    case _ ⇒ segments match {
      case "" :: rest ⇒ IO Done rest.reverse
      case _          ⇒ IO Done segments.reverse
    }
  }
  step(Nil)
}


def readQuery: IO.Iteratee[Option[String]] = IO peek 1 flatMap {
  case QUERY ⇒ IO drop 1 flatMap (_ ⇒ readUriPart(querychar) map (Some(_)))
  case _     ⇒ IO Done None
}


val alpha = Set.empty ++ ('a' to 'z') ++ ('A' to 'Z') map (_.toByte)
val digit = Set.empty ++ ('0' to '9') map (_.toByte)
val hexdigit = digit ++ (Set.empty ++ ('a' to 'f') ++ ('A' to 'F') map (_.toByte))
val subdelim = Set('!', '$', '&', '\'', '(', ')', '*', '+', ',', ';', '=') map (_.toByte)
val pathchar = alpha ++ digit ++ subdelim ++ (Set(':', '@') map (_.toByte))
val querychar = pathchar ++ (Set('/', '?') map (_.toByte))
 
def readUriPart(allowed: Set[Byte]): IO.Iteratee[String] = for {
  str ← IO takeWhile allowed map ascii
  pchar ← IO peek 1 map (_ == PERCENT)
  all ← if (pchar) readPChar flatMap (ch ⇒ readUriPart(allowed) map (str + ch + _)) else IO Done str
} yield all
 
def readPChar = IO take 3 map {
  case Seq('%', rest @ _*) if rest forall hexdigit ⇒
    java.lang.Integer.parseInt(rest map (_.toChar) mkString, 16).toChar
}

def readHeaders = {
  def step(found: List[Header]): IO.Iteratee[List[Header]] = {
    IO peek 2 flatMap {
      case CRLF ⇒ IO takeUntil CRLF flatMap (_ ⇒ IO Done found)
      case _    ⇒ readHeader flatMap (header ⇒ step(header :: found))
    }
  }
  step(Nil)
}
 
def readHeader =
  for {
    name ← IO takeUntil COLON
    value ← IO takeUntil CRLF flatMap readMultiLineValue
  } yield Header(ascii(name), ascii(value))
 
def readMultiLineValue(initial: ByteString): IO.Iteratee[ByteString] = IO peek 1 flatMap {
  case SP ⇒ IO takeUntil CRLF flatMap (bytes ⇒ readMultiLineValue(initial ++ bytes))
  case _  ⇒ IO Done initial
}

def readBody(headers: List[Header]) =
  if (headers.exists(header ⇒ header.name == "Content-Length" || header.name == "Transfer-Encoding"))
    IO.takeAll map (Some(_))
  else
    IO Done None

}

class HttpServer(port: Int) extends Actor {
 
  val state = IO.IterateeRef.Map.async[IO.Handle]()(context.dispatcher)
 
  override def preStart {
    IOManager(context.system) listen new InetSocketAddress(port)
  }
 
  def receive = {
 
    case IO.NewClient(server) ⇒
      val socket = server.accept()
      state(socket) flatMap (_ ⇒ HttpServer.processRequest(socket))
 
    case IO.Read(socket, bytes) ⇒
      state(socket)(IO Chunk bytes)
 
    case IO.Closed(socket, cause) ⇒
      state(socket)(IO EOF
)
      state -= socket
 
  }
 
}

object OKResponse {
  import HttpConstants.CRLF
 
  val okStatus = ByteString("HTTP/1.1 200 OK")
  val contentType = ByteString("Content-Type: text/html; charset=utf-8")
  val cacheControl = ByteString("Cache-Control: no-cache")
  val date = ByteString("Date: ")
  val server = ByteString("Server: Akka")
  val contentLength = ByteString("Content-Length: ")
  val connection = ByteString("Connection: ")
  val keepAlive = ByteString("Keep-Alive")
  val close = ByteString("Close")
 
  def bytes(rsp: OKResponse) = {
    new ByteStringBuilder ++=
      okStatus ++= CRLF ++=
      contentType ++= CRLF ++=
      cacheControl ++= CRLF ++=
      date ++= ByteString(new java.util.Date().toString) ++= CRLF ++=
      server ++= CRLF ++=
      contentLength ++= ByteString(rsp.body.length.toString) ++= CRLF ++=
      connection ++= (if (rsp.keepAlive) keepAlive else close) ++= CRLF ++= CRLF ++= rsp.body result
  }
 
}
case class OKResponse(body: ByteString, keepAlive: Boolean)


object HttpServer {
  import HttpIteratees._
 
  def processRequest(socket: IO.SocketHandle): IO.Iteratee[Unit] =
    IO repeat {
      for {
        request ← readRequest
      } yield {
        val rsp = request match {
          case Request("GET", "ping" :: Nil, _, _, headers, _) ⇒
            OKResponse(ByteString("<p>pong</p>"),
              request.headers.exists { case Header(n, v) ⇒ n.toLowerCase == "connection" && v.toLowerCase == "keep-alive" })
          case req ⇒
            OKResponse(ByteString("<p>" + req.toString + "</p>"),
              request.headers.exists { case Header(n, v) ⇒ n.toLowerCase == "connection" && v.toLowerCase == "keep-alive" })
        }
        socket write OKResponse.bytes(rsp).compact
        if (!rsp.keepAlive) socket.close()
      }
    }
 
}

object Main extends App {
  val port = Option(System.getenv("PORT")) map (_.toInt) getOrElse 8080
  val system = ActorSystem()
  val server = system.actorOf(Props(new HttpServer(port)))
}