I'm working on unpacking a zip file into multiple datasets. I think this is the code path Upload.py UploadToolAction upload_common.py: get_uploaded_datesets new_upload new_history_upload or new_library_upload Then a job gets spooled Which calles add_file in data_source/upload.py And does the expansion of the zip I can unpack the zip and create files in the dataset's path there. But I don't know how to create more dataset associations, and I'm not sure that it makes sense to create datasets on the fly in data_source/upload.py . Should I pass some information along with data_source/upload.py about how to create dataset object and associate them with library/history associations? Or maybe I can pass in some kind of a callback that can handle the dataset expansion? (I'm pretty new to python, but it seems similar to ruby) I thought about a composite dataset, but that seems like overloading that concept. Really the files I'm thinking about uplaoding are 8 independent BAMs or fastqs or whatever – not a set of files that are related to each other. Any suggestions? Brad -- Brad Langhorst New England Biolabs langhorst@neb.com