Scala sys.process example, reading bytes back (create png from Dot)

png_from_dot_file.scala

import java.io.ByteArrayInputStream
import java.io.ByteArrayOutputStream

import scala.sys.process._
import scala.concurrent.ExecutionContext.Implicits.global
import scala.concurrent.Future
import scala.concurrent.blocking
import scala.concurrent.Await
import scala.concurrent.duration._


val dot = """
graph {
  node [shape=box3d];
  a [color=green];
  a -- b;
  a -- c;
  b -- c;
  a -- e;
  f -- g [color=red];
}
"""

case class Dot(code: String) {
  def getBytes: Array[Byte] = code.getBytes
}

def buildGraph(dot: Dot): Future[Array[Byte]] = {
  val outStream = new ByteArrayOutputStream
  val inStream = new ByteArrayInputStream(dot.getBytes)
  val procBuilder = Seq("dot", "-T", "png") #< inStream #> outStream
  val exitcodeFut = Future { blocking { procBuilder.! } }
  exitcodeFut.map { _ =>
    inStream.close
    outStream.close
    outStream.toByteArray
  }
}

val pngData: Array[Byte] = Await.result(buildGraph(Dot(dot)), 10.seconds)