Explicit "here's what to implement guide"

Hi!

I am one of the maintainers of stor a filesystem library that attempts to implement a cross-compatible API for POSIX, OpenStack Swift, S3, and DNAnexus paths. @kyleabeauchamp pointed out your spec and it seemed pretty interesting :) . I am considering providing an alternate version of stor.Path that implements the filesystem_spec API. I know I'm combining a couple things here, but I didn't see a mailing list so I figured I'd ask 'em together.

1. What are the specific methods I need to implement to be compatible with the system? What's the minimal set? Is there an "advanced" set of methods? Is the minimal set all methods on AbstractFileSystem?
2. What does maxdepth mean in the context of S3 or OpenStack Swift? Is it referring to directories delimited by /? Is there a particular ordering that's required? (for example, is it necessary to guarantee that you fully list each "directory" before emitting files in another directory?)

Aside - as a general comment, I wonder if the API would be better served by having all methods work as iterators and/or have all methods support some kind of limit argument. We originally implemented stor to have most file listing methods return lists; in hindsight, this was a mistake - it's much too easy to accidentally write code that tries to list millions of objects, and thus gets really slow or unintentionally expensive.

Interested to test out the system more! :)

Jeff

Start by reading the filesystem_spec API and the AbstractFileSystem interface referenced in the issue, along with stor.Path for compatibility context. Done means documenting the minimal and advanced method sets and defining maxdepth semantics for object stores such as S3 and OpenStack Swift.