Schema trigger code defined in the database is executed by database clients. Any database access by an AppServer agent that invokes database trigger code causes the AppServer agent to run such code. This is because the AppServer application acts as a client to the database.
There is no functional difference between how schema triggers run in an AppServer session and how they run in an ABL client session. However, trigger code executed by an AppServer agent can:
Fail if it requires user input or output to a user interface other than a character user interface
Send any output to the AppServer log file, unless specifically directed otherwise
Invoking schema triggers on a client application raises a basic security issue. Code in the AppServer agent is protected because of encapsulation (the session barrier that isolates AppServer code from the client); code on your client application is not protected.
Fail if it requires user input or output to a user interface other than a character user interface