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spray.io examples, nonblocking, tomcat, and more

spray.io examples, nonblocking, tomcat, and more 

FUNCTIONAL-PROGRAMMING, SCALA, SPRAY, AND AKKA
28 Oct 2014 Tomer-Ben-David Tomer-Ben-David

akka-spray-tomcat-example

akka spray tomcat example in scala

Having serialization done by json spray for you

Lets say you have the following case class (important its a case class for regular classes you will need something a little different)
case class Person(val name: String)
and you want json-spray to serialize it you will need the define the following implicit you can just define it beside your case class in the same file.
object PersonJsonImplicits extends DefaultJsonProtocol {
  implicit val impPerson = jsonFormat1(Person)
}
Then you can use toJson on your pimped class: ** You must import spray.json._ otherwise toJson won’t be recognized! **
import spray.json._
new Person("somename").toJson
note the 1 in jsonFormat1 this means your case class has single parameter if it had 2 you would use… jsonFormat2 :)

Async with Future

Remember: spray uses a single actor to handle incoming requests. This means you cannot run any blocking code in the handling actor.
// In spray main request handler actor.,
complete {
  // NO BLOCKING CODE HERE
}
So you have two options (or 3). 1. Route the request to another actor handle it there, use ask ? pattern to get back a future. complete {} will then know to handle the Future. (nothing special required). 2. Use directly a future - I like that one better its more clear.
complete {
  Future {
    Thread.sleep(5000) // blocking example.
    "tada.."
  }
}
you may need to define above the implicit executionContext that the Future will run in and also the implicit timeout

Async with detach

now if you want to handle your request in an async way you don’t really need to create actors spray can do that for you just wrap your handling with detach { as following:
detach() { // this make the below operation async (note for your app to really be async you should  not block the underlying thread!)
          respondWithMediaType(`text/html`) { // XML is marshalled to `text/xml` by default, so we simply override here
            complete {
              <html>
Note that although we called detach() if you have inside the code which detach calls some blocking code this would still mean it would block the thread on which detach is running therefore if you do any blocking getyou should
still wrap it in a future and have a callback for it (same as you should not block from within handling of a message in an actor).

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