Principal question: MVC

Hi all,

I have some problems understanding the logic behind SAP's MVC-pattern - the tutorials are not very useful for they omit the interesting and difficult parts. But perhaps I'm simply thinking in the wrong direction so anybody who puts me on the right track is welcomed!

Here is one thing I really don't get - either I'm mistaken or SAP is:

Why is the member ERROR of class CL_BSP_MODEL protected? In my view that doesn't make sense, ERROR should either be a parameter for any set-get-method (not my preferred solution) or it should be public (read-only). How in the current framework is a controller supposed to send a meaningful message to the user when a set-method of a model failed? (I know, there is a quite stupid message saying, that there an error occured while transferrring data to the model)

Another thing that is not strictly MVC-related: why does CL_BSP_MESSAGE not use the "normal" SAP-message-format? Why can't I save any further information (long text infos) in it?

Ok, enough for now, I would also like to discuss appropriate patterns for BSP-transaction-programming, but I keep that for later... 😉

best regards,

Stephan