Data Types in Schema - Database Data Connection vs. Web Service

[em]

Hi,
I get the following difference in data types within IP generated schemas:
a) When using a (direct) DB data Connection, the data types in the IP
generated schema correspond to the DB data types (i.e. int, string, date, ...)
b) When using a web service to access the DB and then creating an XML
document that is returned to IP, all data types in the generated schema are
of type "string". My question: How can I bring the DB data types into the IP
generated schema when using a web service to access the DB ?
Thanks for any advice!