protected virtual void HandleChangeGroupsOperation(LitePeer peer, ChangeGroups changeGroupsRequest, SendParameters sendParameters)
        {
            // get the actor who send the operation request
            Actor actor = this.GetActorByPeer(peer);
            if (actor == null)
            {
                return;
            }

            actor.RemoveGroups(changeGroupsRequest.Remove);

            if (changeGroupsRequest.Add != null)
            {
                if (changeGroupsRequest.Add.Length > 0)
                {
                    foreach (var groupId in changeGroupsRequest.Add)
                    {
                        ActorGroup group;
                        if (!this.actorGroups.TryGetValue(groupId, out group))
                        {
                            group = new ActorGroup(groupId);
                            this.actorGroups.Add(groupId, group);
                        }
                        actor.AddGroup(group);
                    }
                }
                else
                {
                    foreach (var group in this.actorGroups.Values)
                    {
                        actor.AddGroup(group);
                    }
                }
            }
        }
        /// <summary>
        ///   Called for each operation in the execution queue.
        ///   Every <see cref = "Room" /> has a queue of incoming operations to execute. 
        ///   Per game <see cref = "ExecuteOperation" /> is never executed multi-threaded, thus all code executed here has thread safe access to all instance members.
        /// </summary>
        /// <param name = "peer">
        ///   The peer.
        /// </param>
        /// <param name = "operationRequest">
        ///   The operation request to execute.
        /// </param>
        /// <param name = "sendParameters">
        ///   The send Parameters.
        /// </param>
        protected override void ExecuteOperation(LitePeer peer, OperationRequest operationRequest, SendParameters sendParameters)
        {
            try
            {
                base.ExecuteOperation(peer, operationRequest, sendParameters);

                if (Log.IsDebugEnabled)
                {
                    Log.DebugFormat("Executing operation {0}", (OperationCode)operationRequest.OperationCode);
                }

                switch ((OperationCode)operationRequest.OperationCode)
                {
                    case OperationCode.Join:
                        {
                            var joinRequest = new JoinRequest(peer.Protocol, operationRequest);
                            if (peer.ValidateOperation(joinRequest, sendParameters) == false)
                            {
                                return;
                            }

                            if (this.LogQueue.Log.IsDebugEnabled)
                            {

                                this.LogQueue.Add(
                                    new LogEntry(
                                        "ExecuteOperation: " + (OperationCode)operationRequest.OperationCode,
                                        "Peer=" + peer.ConnectionId));
                            }

                            joinRequest.OnStart();
                            this.HandleJoinOperation(peer, joinRequest, sendParameters);
                            joinRequest.OnComplete();
                            break;
                        }

                    case OperationCode.Leave:
                        {
                            var leaveOperation = new LeaveRequest(peer.Protocol, operationRequest);
                            if (peer.ValidateOperation(leaveOperation, sendParameters) == false)
                            {
                                return;
                            }

                            if (this.LogQueue.Log.IsDebugEnabled)
                            {

                                this.LogQueue.Add(
                                    new LogEntry(
                                        "ExecuteOperation: " + (OperationCode)operationRequest.OperationCode,
                                        "Peer=" + peer.ConnectionId));
                            }

                            leaveOperation.OnStart();
                            this.HandleLeaveOperation(peer, leaveOperation, sendParameters);
                            leaveOperation.OnComplete();
                            break;
                        }

                    case OperationCode.RaiseEvent:
                        {
                            var raiseEventOperation = new RaiseEventRequest(peer.Protocol, operationRequest);
                            if (peer.ValidateOperation(raiseEventOperation, sendParameters) == false)
                            {
                                return;
                            }

                            raiseEventOperation.OnStart();
                            this.HandleRaiseEventOperation(peer, raiseEventOperation, sendParameters);
                            raiseEventOperation.OnComplete();
                            break;
                        }

                    case OperationCode.GetProperties:
                        {
                            var getPropertiesOperation = new GetPropertiesRequest(peer.Protocol, operationRequest);
                            if (peer.ValidateOperation(getPropertiesOperation, sendParameters) == false)
                            {
                                return;
                            }

                            getPropertiesOperation.OnStart();
                            this.HandleGetPropertiesOperation(peer, getPropertiesOperation, sendParameters);
                            getPropertiesOperation.OnComplete();
                            break;
                        }

                    case OperationCode.SetProperties:
                        {
                            var setPropertiesOperation = new SetPropertiesRequest(peer.Protocol, operationRequest);
                            if (peer.ValidateOperation(setPropertiesOperation, sendParameters) == false)
                            {
                                return;
                            }

                            setPropertiesOperation.OnStart();
                            this.HandleSetPropertiesOperation(peer, setPropertiesOperation, sendParameters);
                            setPropertiesOperation.OnComplete();
                            break;
                        }

                    case OperationCode.Ping:
                        {
                            peer.SendOperationResponse(new OperationResponse { OperationCode = operationRequest.OperationCode }, sendParameters);
                            break;
                        }

                    case OperationCode.ChangeGroups:
                        {
                            var changeGroupsOperation = new ChangeGroups(peer.Protocol, operationRequest);
                            if (peer.ValidateOperation(changeGroupsOperation, sendParameters) == false)
                            {
                                return;
                            }

                            changeGroupsOperation.OnStart();
                            this.HandleChangeGroupsOperation(peer, changeGroupsOperation, sendParameters);
                            changeGroupsOperation.OnComplete();
                            break;
                        }
                    default:
                        {
                            string message = string.Format("Unknown operation code {0}", (OperationCode)operationRequest.OperationCode);
                            peer.SendOperationResponse(
                                new OperationResponse { OperationCode = operationRequest.OperationCode, ReturnCode = -1, DebugMessage = message }, sendParameters);

                            if (Log.IsWarnEnabled)
                            {
                                Log.Warn(message);
                            }
                        }

                        break;
                }
            }
            catch (Exception ex)
            {
                Log.Error(ex);
            }
        }