Add iteratee example

build.sbt

@@ -332,7 +332,7 @@ lazy val examples = project
       "com.github.finagle" %% "finagle-oauth2" % finagleOAuth2Version
     )
   )
-  .dependsOn(core, circe, jackson, oauth2)
+  .dependsOn(core, circe, jackson, oauth2, iteratee)
 
 lazy val benchmarks = project
   .settings(moduleName := "finch-benchmarks")

examples/src/main/scala/io/finch/iteratee/Main.scala

@@ -0,0 +1,73 @@
+package io.finch.iteratee
+
+import scala.util.Random
+
+import com.twitter.finagle.Http
+import com.twitter.util.{Await, Future}
+import io.catbird.util._
+import io.circe.generic.auto._
+import io.finch._
+import io.finch.circe._
+import io.iteratee.{Enumerator, Iteratee}
+
+/**
+  * A Finch application featuring iteratee-based streaming support.
+  * This approach is more advanced and performant then basic [[com.twitter.concurrent.AsyncStream]]
+  *
+  * There are three endpoints in this example:
+  *
+  *  1. `sumJson` - streaming request
+  *  2. `streamJson` - streaming response
+  *  3. `isPrime` - end-to-end (request - response) streaming
+  *
+  * Use the following sbt command to run the application.
+  *
+  * {{{
+  *   $ sbt 'examples/runMain io.finch.iteratee.Main'
+  * }}}
+  *
+  * Use the following HTTPie/curl commands to test endpoints.
+  *
+  * {{{
+  *   $ curl -X POST --header "Transfer-Encoding: chunked" -d '{"i": 40} {"i": 2}' localhost:8081/sumJson
+  *
+  *   $ http --stream GET :8081/streamJson
+  *
+  *   $ curl -X POST --header "Transfer-Encoding: chunked" -d '{"i": 40} {"i": 42}' localhost:8081/streamPrime
+  * }}}
+  */
+object Main {
+
+  private val stream: Stream[Int] = Stream(Random.nextInt()).flatMap(_ => stream)
+
+  val sumJson: Endpoint[Result] = post("sumJson" :: enumeratorJsonBody[Number]) { (enum: Enumerator[Future, Number]) =>
+    enum.into(Iteratee.fold[Future, Number, Result](Result(0))(_ add _)).map(Ok)
+  }
+
+  val streamJson: Endpoint[Enumerator[Future, Number]] = get("streamJson") {
+    Ok(Enumerator.enumStream[Future, Int](stream).map(Number.apply))
+  }
+
+  val isPrime: Endpoint[Enumerator[Future, IsPrime]] = post("streamPrime" :: enumeratorJsonBody[Number]) {
+    (enum: Enumerator[Future, Number]) => Ok(enum.map(_.isPrime))
+  }
+
+  def main(args: Array[String]): Unit =
+    Await.result(Http.server
+      .withStreaming(enabled = true)
+      .serve(":8081", (sumJson :+: streamJson :+: isPrime).toServiceAs[Application.Json])
+    )
+
+}
+
+case class Result(result: Int) {
+  def add(n: Number): Result = copy(result = result + n.i)
+}
+
+case class Number(i: Int) {
+
+  def isPrime: IsPrime = IsPrime(!(2 +: (3 to Math.sqrt(i.toDouble).toInt by 2) exists (i % _ == 0)))
+
+}
+
+case class IsPrime(isPrime: Boolean)