upload and download file to BDM Database

Hello, does anybody here know how to upload excel file and download excel file to bdm database? previously i created similar question here https://community.bonitasoft.com/node/33108#node-33131, but the sample given wasn't suit to my project. So let me explain a bit what my project need. In my Project there is a features called upload and download excel file to or from BDM database. Upload and download is a seperate process.