Fedora Repository Specification - Fixity

Hello LDP-Next,
As both an update from the Fedora Repository LDP community and an
invitation for input, we are continuing the effort of specifying additional
capabilities to the LDP specification.

Fedora Repositories require five "services" beyond the basic CRUD
operations afforded by LDP, specifically:
- Fixity Checking
- Authorization - aligning Web Access Controls
- Versioning - aligning with Memento
- Batch Atomic Operations (i.e. transactions-lite)
- Messaging - SPI - aligning with Activity Streams 2.0

The in-progress specification is found here:
http://fcrepo.github.io/fcrepo-specification/

Your input and comments would be greatly welcomed either on this list or as
GitHub issues on the above repository.

Most currently, we are discussing options for the Fixity Checking service.
The specification requires two flavors of Fixity:
1. On-transmission, which is supported with the standard Digest header (
https://tools.ietf.org/html/rfc3230#section-4.3.2)
2. On-demand, which is intended to support both returning a requested
digest, or comparing a client-provided digest with a server-calculated
value.

It is with the on-demand mode of interaction that your input would be most
immediately appreciated.

The discussion is taking place within the following Google-Doc:
https://docs.google.com/document/d/1Nm-LFyUhCl-et4UsdePuMJ_Zu23Mot4FiEpEMke_JH4/edit?usp=sharing

Once we have consensus, the appropriate text will move to the previously
mentioned GitHub repository.

Regards,
Andrew Woods