https://xxxxxx/v4/live_engine_http_pk/create_battle?sdkappid=88888888&identifier=admin&usersig=xxx&random=99999999&contenttype=json

{
    "FromRoomId":"pk-1",  //Caller's room ID in PK
    "ToRoomIdList":["pk-2","pk-3"], //List of callee's room IDs in PK
    "Duration":60000, //Duration of PK
    "ExtensionInfo":"extension pk"
}

{
  "ErrorCode": 0, 
  "ErrorInfo": "",
  "ActionStatus": "OK",
  "RequestId": "requestId-123-456",
  "Response":{
    "BattleId": "battleid1",
    "Result": [
         {
            "RoomId": "pk-2",
             // 0 indicates initiate successfully
             // 3 indicates that it is already in another PK. 
             // 5 System error

             "ResultCode": 0, 
             "ResultMessage": "",
         },
         {
            "RoomId": "pk-3",
            "ResultCode": 0, 
            "ResultMessage": "",
         }
     ],
  }
}