Migration of BW to version 7.0

Hello,

Can anybody help me regarding the migration of a BW application? is there any instructions guide explaining the whole process?. I am on this now and I do not know if I have to generate migration before transforming the transfer rules. Is it necessary to migrate the data sources from all source systems? or just for the ones from BW 3.x?

Any help you we very well received.

Thanks and regards,

Victor