added ping command.

aws-experiment-launch/experiment/commander/main.go

@@ -94,7 +94,7 @@ func dictateNode(addr string, command string) {
 		log.Printf("Failed to send command to %s", addr)
 		return
 	}
-	log.Printf("Send: %s", command)
+	log.Printf("Send \"%s\" to %s", command, addr)
 
 	// read response
 	buff := make([]byte, 1024)

aws-experiment-launch/experiment/soldier/main.go

@@ -96,6 +96,10 @@ func handleCommand(command string, w *bufio.Writer) {
 		{
 			handleKillCommand(w)
 		}
+	case "ping":
+		{
+			handlePingCommand(w)
+		}
 	}
 }
 
@@ -142,6 +146,11 @@ func handleKillCommand(w *bufio.Writer) {
 	logAndReply(w, "Kill command done.")
 }
 
+func handlePingCommand(w *bufio.Writer) {
+	log.Println("Ping command")
+	logAndReply(w, "I'm alive")
+}
+
 func logAndReply(w *bufio.Writer, message string) {
 	log.Println(message)
 	w.Write([]byte(message))