DSS provides delivery of data files via FTP/SFTP for delivery direct clients. Can a user/client send, via FTP/SFTP, an input request , for example a instrument/RIC list etc, and get back response from DSS with data for just those instruments ?
Please see DATASCOPE SELECT FTP USER GUIDE, the chapter "Generating Custom Solutions Reports with FTP/SFTP " should be useful. You should be able to define instrument lists and templates, the requests can be customized in the way that is analogous to the Datascope GUI and REST API, creating instrument lists.
For a new task however, in my opinion, HTTP REST and GUI definition is much simpler and quicker, and is preferred, please see quick Datascope REST API Tutorials to help get started with HTPP REST quickly and easily.
Hope this helps