It depends on your requirements.
This project should be a good start.
@Erel,
in a few words, I have 3 main roles :
1) Order submitter : access catalog items (read only) and create orders
2) Order receiver : read / update the orders submitted
3) Catalog & Order Administrator : read / update / create catalog items and read / update / create Orders
In this scenario, wich is the best approach using B4A app as client and B4J server ?
1) Implement a single app using "Conditional Compilation & Build Configurations" to handle each role
2) Implement a specific app for each role (in this case 3 different apps).
Thanks