Is it possible to have a realtime updation of graphics.

Is it possible to have a realtime updation of graphics.

I have a question regarding real time updation  of colour of certain graphics.
For example, suppose that I own a lodge having number of rooms.
Customer 'ABC' is booking a room(i.e.room no. 10) from Delhi at the same time another customer 'XYZ' is booking the same room(i.e.room no. 10) from Chennai.

Now the problem is that if customer 'ABC' booked the room(i.e.room no. 10) one second before 'XYZ'. How can a booking agent at Chennai come to know that the room is booked, so that he can tell customer 'XYZ'.

So is it possible to have layout of my lodge on internet showing the booking status online with different colours. The colours of different rooms will show 1.Empty, 2.Booked, 3.Being booked. It is some what like railway reservation system.