File Open Dialog in CRM Web UI screen

Hi,

I want to select a file from the presentaion server through a custom transaction defined in the Transaction launcher,

and the cl_gui_frontend_services class does not allow to select files from the WEB UI. Is there an equivalent to this class for the web UI ? .

Also, I read in this forum that we can use the GS_FILE_UPLOAD component and I dont know how to use it.

Thanks