Use the BAPI Wrapper Wizard to identify or write BAPI wrappers that make the desired SAP data available to your application.
For detailed instructions, see the SAP documentation, Creating BAPI Wrappers Using the Wizard, at http://help.sap.com/saphelp_nwmobile71/helpdata/en/3e/1e6323e59a4dc1b236f4905960ccdd/content.htm