[writing-async-app-in-scala-part-3] direct executor context usage

DirectExecutorContextUsage.scala

def rpcCall: Future[String]
def daoCall(id: String): Future[Int]
def extractId(idStr: String): Future[String]
def convertDbValue(value: Int): Future[Int]

import directExecutionContext

for {
  idStr <- rpcCall
  id <- extractId(idStr) // executed in RPC execution context
  valueFromDb <- daoCall(id)
  value <- convertDbValue(valueFromDb) // executed in DAO execution context
} yield value // executed in DAO execution context