(Java) Real time web application

During my studies I have to make project connected with programming in Java. I learn Java from few months and I would like to make something interesting (not application for bank, library, car renting etc). I'm wondering whether it is possible to create real-time web game/application, where you can type something and your friend on another laptop see this message and can send you response? (using internet/bluetooth) If yes, what I should look for to find information about this type of applications?

Thank you in advance for any response.