I believe that you will find interesting this links:
Hope it helps.
There are several ways to extract data from BW:
1. extract data from physical tables - by using QV SAP connector (requires to import QV transports in BW)
2. extract BEx query result - by using QV SAP OLAP connector
3. others, usually less usefull: QV extractor connector, BAPI connector etc...
here's a relevant link: