Handling messages

Dear all,

in ABAP world if I e.g. move goods from one storage to another I can use a BAPI for it. That BAPI would require e.g. material number, source and destination storage. Especially if something goes wrong I can look into the bapireturn table and loop over the messages and display them to the user.

In SEGW / JSON world I would build an entity with e.g. the attributes: material number, source and destination storage. If something goes wrong how can I return the messages to the HTML5 application?

Thanks and regards,

Rene