Is it possible to write backend code?

Hey guys.
My app is using ad networks, which give the users rewards of a virtual currency.
for that, I need to have a php/java code that is running on the server that they can call with a post. this code will have some basic logic and query, update tables.

is that possible with backendless?

Yes:

https://backendless.com/documentation/business-logic/java/bl_overview.htm
https://backendless.com/documentation/business-logic/php/bl_overview.htm
https://backendless.com/documentation/api-engine