private OperationResponse ItemOperationSubscribeItem(Item item, SubscribeItem operation)
        {
            if (item.Disposed)
            {
                return operation.GetOperationResponse((int)ReturnCode.ItemNotFound, "ItemNotFound");
            }

            this.interestItems.SubscribeItem(item);

            var subscribeEvent = new ItemSubscribed
            {
                ItemId = item.Id,
                ItemType = item.Type,
                Position = item.Position,
                PropertiesRevision = item.PropertiesRevision,
                Rotation = item.Rotation
            };

            var eventData = new EventData((byte)EventCode.ItemSubscribed, subscribeEvent);
            this.Peer.SendEvent(eventData, new SendParameters { ChannelId = Settings.ItemEventChannel });

            if (operation.PropertiesRevision.HasValue == false || operation.PropertiesRevision.Value != item.PropertiesRevision)
            {
                var properties = new ItemPropertiesSet
                    {
                        ItemId = item.Id,
                        PropertiesRevision = item.PropertiesRevision,
                        PropertiesSet = new Hashtable(item.Properties)
                    };
                var propEventData = new EventData((byte)EventCode.ItemPropertiesSet, properties);
                this.Peer.SendEvent(propEventData, new SendParameters { ChannelId = Settings.ItemEventChannel });
            }

            // don't send response
            operation.OnComplete();
            return null;
        }
        private OperationResponse ItemOperationSetProperties(Item item, SetProperties operation, SendParameters sendParameters)
        {
            MethodReturnValue result = this.CheckAccess(item);
            if (result.IsOk)
            {
                item.SetProperties(operation.PropertiesSet, operation.PropertiesUnset);
                var eventInstance = new ItemPropertiesSet
                    {
                        ItemId = item.Id,
                        PropertiesRevision = item.PropertiesRevision,
                        PropertiesSet = operation.PropertiesSet,
                        PropertiesUnset = operation.PropertiesUnset
                    };

                var eventData = new EventData((byte)EventCode.ItemPropertiesSet, eventInstance);
                sendParameters.ChannelId = Settings.ItemEventChannel;
                var message = new ItemEventMessage(item, eventData, sendParameters);
                item.EventChannel.Publish(message);

                // no response sent
                operation.OnComplete();
                return null;
            }

            return operation.GetOperationResponse(result);
        }