How a JAVA program can access HANA database

Hi Experts,

I am trying to understand what best things we can do with HANA DATABASE.

My ECC is recently moved to HANA database.

A legacy system is creating a webservice and wants to access our database directly, they need some PO information.

One way is to send data to them through interfaces and they will store them in their database and can access it as and when needed.

I am looking for someway, so that they can access SAP database directly and get the data.

Please help with inputs, I understand that it may be very naive question.

Thanks & Regards,

Uttam