#20 MESSAGE Still Works ​

An ABAP developer has thirty years of habits around messages, and the good news is that most of them carry over unchanged. What changes is where the message ends up.

A toast for what needs no acknowledgment, a box for what does:

    client->message_toast_display( `Saved` ).

    client->message_box_display( text = `Order is locked by another user`
                                 type = `error` ).

The old structures go straight in. sy after a MESSAGE ... INTO, a BAPIRET2 table from a BAPI, an exception object from a CATCH — the framework reads the text, the type and the details out of each:

    MESSAGE ID `NET` TYPE `I` NUMBER `001` INTO DATA(dummy).
    client->message_box_display( sy ).

    client->message_box_display( t_bapiret ).

    TRY.
        DATA(x) = 1 / 0.
      CATCH cx_root INTO DATA(lx).
        client->message_box_display( lx ).
    ENDTRY.

Which means the message class, the T100 text and the translation tooling around them are exactly as useful as they were before. A text element or a message class is still the way a string gets translated, because the app is an ABAP class and there is no i18n file beside it. Your translators keep their transaction; nobody exports a properties file to anybody.

What is different is the exception that gets away. There is one catch in the framework, in the HTTP handler, and an exception that escapes main( ) travels all the way up to it. The roundtrip ends with HTTP 500, the database work of that roundtrip is rolled back, and the browser shows an Application Error, please restart overlay with the exception chain behind a Details button. There is no continue: the roundtrip that would have carried the app's next state is the one that failed, so the user restarts, and the draft brings them back to where they were.

That is the fallback, and reaching it means the user has lost the screen. Anything predictable — a failed conversion, a locked object, a service that is not there — is caught where it happens and shown as a box, which costs the user one click instead of one restart.

One setting belongs in every production system, and it is the sort of thing that is embarrassing to discover during a penetration test. The 500 body carries source positions, RTTI names and system context — everything a developer wants and considerably more than a browser should get. check_hide_error_details in the user exit turns the body into a bare Internal Server Error and leaves everything else as it is.

The message classes, the texts and the translation stay. Only the dump looks different.