Application.scala

case class MyData(uData: String, otherData: String)

object Application1 extends App {

  // get a driver instance driver  
  val driver = ReactiveCouchbaseDriver()
  // get the default bucket  
  val bucket = driver.bucket("default")
  implicit val fmt = Json.format[MyData]

  bucket.atomicallyUpdate[MyData]("myKey") { currentValue =>
    val usefulData = currentValue.uData
    WS.url(s"http://myWebservice.com/service?data=${usefulData}").get().map { value =>
      usefulData.copy(uData = value)
    }
  }.onComplete {
    case _ => driver.shutdown()
  }
}

So what happens if something else tries to update "mykey" while the atomic update is running?