Can BW load data from PI for systems like Oracle, SQL?

Does anyone know if it is possible to load transactional data from Oracle or SQL systems via PI (Process Integration) to BW, assuming PI is connected with 3rd party systems (which are Oracle, SQL based) and BW?

As far as I know, interface between PI and BW is only for exchanging messages, which is for very limited volume of data. I may be wrong on this. Any clarification is greatly appreciated!

Bill