Handheld device connection to SAP function modules

Hi guys,

I have this requirement.

We have SAP 4.7 dumps master data into SQL database, and then our warehouse handheld devices are reading data from SQL data base.

in our case SAP dumps data once in 4 hours to SQL data base and handheld reads so this is not real time data if any changes are made.

Now i felt we can do better in this. how to read SAP Bapis directly to Handheld.What steps / servers i need to have for this stepup instead of using SQL in between.

We have SAP PI also in organisation , can we use it for any communication.

for example i need to call salesorder bapi in sap from handheld, can some exactly tell all the steps involved.

for further info my handheld is a .Net product, or windows based device.

let me know if anyone needs further info.

Thanks

Sandeep