[galaxy-dev] Using synchronous method to upload multiple files

Hi all, I've set up a simple tool using the synchronous method to upload a file on galaxy. I'm able to visit the external link, select and upload a file by the list. The script that I use is data_source.py and the 'command' part in the xml configuration is the same as the ucsc xml config (ucsc_tablebrowser.xml). But my purpose is to import multiple files. Have you any idea how I can set a way to import/upload multiple files by using the synchronous method? Thank in advance, Best regards Daniele