ExchangeRateService.scala

trait ExchangeRatesService extends Service {

  def getExchangeRate(fromUnit: String,
                      toUnit: String
                     ): ServiceCall[NotUsed, ExchangeRatio]

  def setExchangeRate(fromUnit: String,
                      toUnit: String
                     ): ServiceCall[Rate, NotUsed]

  def descriptor(): Descriptor =
    named("exchangerates")
      .`with`(
        restCall(
            Method.GET, 
            "/api/exchangerates/:fromUnit/:toUnit", 
            getExchangeRate _
        ),
        restCall(
            Method.PUT, 
            "/api/exchangerates/:fromUnit/:toUnit", 
            setExchangeRate _
        )
      )
      .`with`(new MicroserviceExceptionSerializer)
      .withAutoAcl(true)
}