samba - Nov 2011 - Difference between simple ui_ops and subunit ui_ops.

Hi,

I am not able to get why subunit ui_ops and subunit ui_ops are there in
samba code.

When I run the raw tests, always subunit ui_ops are used. Then I am not
able to understand where is simple ui_ops are used??

Please help me ASAP.

Regards,
Nishant