The answer to your question.whether the REST code generator works with stored procedures is no. A code generator cannot know what happens inside a stored procedure so it is impossible to build a code generator based off stored procedures only.
Having said this, the opposite is true: it would be entirely possible to generate stored procedures based on the tables in the data model. However, the SPARK platform does not do that as it favors dynamic SQL over stored procedures.
I hope this helps.
Jack Poorte, Dec 04, 2013