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Version: ZIO 2.x

Introduction to ZIO Http

Table of Contents

Http

Creating a "Hello World" app​

import zio.http._

val app = Http.text("Hello World!")

An application can be made using any of the available operators on zio.Http. In the above program for any Http request, the response is always "Hello World!".

Routing​

import zio.http._

val app = Http.collect[Request] {
  case Method.GET -> Root / "fruits" / "a"  => Response.text("Apple")
  case Method.GET -> Root / "fruits" / "b"  => Response.text("Banana")
}

Pattern matching on route is supported by the framework

Composition​

import zio.http._

val a = Http.collect[Request] { case Method.GET -> Root / "a"  => Response.ok }
val b = Http.collect[Request] { case Method.GET -> Root / "b"  => Response.ok }

val app = a <> b

Apps can be composed using the <> operator. The way it works is, if none of the routes match in a , or a NotFound error is thrown from a, and then the control is passed on to the b app.

ZIO Integration​

val app = Http.collectM[Request] {
  case Method.GET -> Root / "hello" => ZIO.succeed(Response.text("Hello World"))
}

Http.collectM allow routes to return a ZIO effect value.

Accessing the Request​

import zio.http._

val app = Http.collect[Request] {
  case req @ Method.GET -> Root / "fruits" / "a"  =>
    Response.text("URL:" + req.url.path.asString + " Headers: " + r.headers)
  case req @ Method.POST -> Root / "fruits" / "a" =>
    Response.text(req.bodyAsString.getOrElse("No body!"))
}

Testing​

Tests suites could be implemented using zio-test library, as following:


import zio.test._
import zio.http._
import zio.test.Assertion.equalTo

object Spec extends DefaultRunnableSpec {
  val app = Http.collect[Request] { case Method.GET -> !! / "text" =>
    Response.text("Hello World!")
  }

  def spec = suite("http")(
    test("should be ok") {
      val req         = ???
      val expectedRes = app(req).map(_.status)
      assertZIO(expectedRes)(equalTo(Status.Ok))
    },
  )
}

Socket

Creating a socket app​

import zio.socket._

private val socket = Socket.collect[WebSocketFrame] {
  case WebSocketFrame.Text("FOO")  => ZStream.succeed(WebSocketFrame.text("BAR"))
}

private val app = Http.collect[Request] {
  case Method.GET -> Root / "greet" / name  => Response.text(s"Greetings {$name}!")
  case Method.GET -> Root / "ws" => Response.socket(socket)
}

Server

Starting an Http App​

import zio.http._
import zio.http.Server
import zio._

object HelloWorld extends App {
  val app = Http.ok

  override def run(args: List[String]): URIO[zio.ZEnv, ExitCode] =
    Server.start(8090, app).exitCode
}

A simple Http app that responds with empty content and a 200 status code is deployed on port 8090 using Server.start.

Examples