Update existing document in ES?

ES_Update.md

Have existing document already in ES

{
  "service" : "A",
  "timestamp" : "2014-06-06T12:12:59.456+00:00"
}

and want to update it to get this

{
  "service" : "A",
  "timestamp" : "2014-06-06T12:11:59.456+00:00",
  "mapping" : [
    {"subcmd":"X", "finished":"2014-06-06T18:12:59.456+00:00", "status" : "success"},
    {"subcmd":"Y", "finished":"2014-06-06T18:13:59.456+00:00", "status" : "failed"}
  ]
}

What else, other than dynamic script, could I use to get this with one request?