The user code needs to be in server.R or ui.R or global.R. To be modular and assist in maintenance, it is nice to have short source files. Is it possible to have the code in multiple R files with filenames that I choose, if the application will have lots of functions, such as to calculate various numerical summaries of the data ? Something like the Collate field of the DESCRIPTION file of typical R packages, perhaps ? I suppose it is possible to have many source function calls at the beginning of server.R, but could there be a neater way ?