Looking for web application example

I need to recreate a server application that responds to calls from an existing client desktop application that I have written in xojo.
The current AWS server will be dismissed for a different reason.
The desktop application uses REST to communicate with the server, upload a file, get the result of the computation, and download the file.

I am looking for some examples of how to do a web application with xojo, which can scale as the request increases.
The web application needs to store data in a DB, and do computation on file PDF uploaded.

My experience with this is quite low on the web area.

Thanks for any help