AppWarp does not store data on the server. However, you can use App42 Storage module to create your custom wall.
Whenever a user posts something to his wall, you can store the same to his info doc in App42 Storage module in JSON format. Whenever, his friend want to see his wall, you can fetch the details from his info doc and render the same in your app UI.
Let me know if you have any further queries, I will be happy to help you.