HIFIS & Nextcloud: VO Federation for EFSS

<!--HTML-->After two years of planning for Virtual Organisations (VO; Community AAI[1] based group of any size) as the basis for a new kind of EFSS Federation [2,3] by HIFIS in coordination with the CS3 community, the development of this new feature for the Nextcloud software has been completed, thanks to the strong support of Nextcloud and their subcontractor publicplan. Admins of Nextcloud instances now have the option of joining a federation in the context of any Community AAI which supports the necessary interfaces [4]. This will enable users to share with VOs which they are a member of within these Community AAIs, while every other VO member who has connected their Community AAI account will receive the share, no matter on which Nextcloud instance within the federation they work on. This first approach on federated group sharing builds upon the OCM protocol [5], adding a new share type to it. We want to propose this new extension of OCM to the CS3 and OCM Community and discuss it in depth, to achieve a level of standardisation which will allow for further software vendors to implement similar features and for the research community to span VO based federations across providers of heterogeneous EFSS solutions. [1] AARC Blueprint for Community AAIs: https://aarc-project.eu/architecture/ [2] CS3 contribution 2021: https://indico.cern.ch/event/970232/contributions/4157924/ [3] CS3 contribution 2022: https://indico.cern.ch/event/1075584/contributions/4658939/ [4] SCIM rfc: https://www.rfc-editor.org/rfc/rfc7644.html [5] OCM protocol: https://wiki.geant.org/display/OCM/Open+Cloud+Mesh