Samvera and Fedora 4 - FAQ

This page of FAQs is offered for information only.  We shall try to keep it accurate and up to date but offer no warranty that it is fully correct at any given time.


Where can I find out more about Fedora 4?

The Fedora 4 wiki pages can be found here: Fedora Repository Home

DuraSpace also ran a webinar series on Fedora 4 beta pilots; the series is archived at

Does Samvera support the effort to develop Fedora 4?

Yes!  The Samvera Community was, and remains, one of the driving forces behind the development of a Fedora version 4.  From the beginning of that effort Samvera developers have been checking that the new code will serve Samvera's needs and we have had a test installation running against it.


Is Samvera developing new gems to work with Fedora 4?

Fedora v4 is significantly different from v3 and the Fedora APIs have changed significantly.  New versions of the Samvera gems that interact with Fedora are being developed alongside the development of the Fedora 4 code.


What is the timeline for a version of Samvera that will work with Fedora 4?

The Fedora team hopes to have a version 4.0 available by the end of the calendar year 2014 (a beta version is available as of June 2014).  This version of Fedora is intended to support only new installations - there will be no provision for migrating from a Fedora 3.x repository.  We anticipate a first, stable version of a 4.0 compatible Samvera gem-set shortly after the Fedora release.  Fedora 4.1, supporting migration from 3.x, will be released sometime in 2015 and, again, a 4.1 compatible Samvera gem-set will be released shortly after that event.


How long will the Samvera Community support the Fedora 3.x compatible gems that we are using at the moment?

Samvera is in use in a wide variety of institutions and organizations.  It is unrealistic to expect that they will all switch to a Fedora 4 based system quickly.  Indeed, some of the Samvera installations are preservation repositories which are likely to wait some time to be sure of Fedora 4's stability before committing their content to a new system.  Whilst there are Samvera sites using Fedora 3.x compatible gems there is likely to be some level of support for them within the Samvera Community; that said, it is inevitable that over time Samvera developers will concentrate more and more on Fedora 4.x based systems.


When I eventually migrate to Fedora 4 and swap to the Fedora 4 gemset, how much of my local code written around the F3 gemset is likely to break?  

For the most part the changes will be painless.  There are no changes to OM or Solrizer.  We've been very conscious of keeping the old API in place in ActiveFedora and adding deprecations. The primary place you will see issues is in the API for permissions within Samvera-access-controls.  These changes were required to move to the RDF based web ACL "standard".   Furthermore, the changes better align with the Rails and ActiveRecord API.   The most difficult part will be moving the data out of Fedora 3 and into Fedora 4.  

For sites beginning Samvera development from scratch

If I’m starting Samvera development anew, should I begin with Fedora 3 or Fedora 4?

For sites maintaining existing Samvera applications...

Will I be able to keep running Samvera on Fedora 3?

When should / do I need to move from Fedora 3 to Fedora 4?

When I move to Fedora 4, do I need to move from XML to RDF?

  • No. Fedora 4 accommodates Fedora 3-style XML datastreams.

    • XML will continue to be supported as part of Fedora 4

  • If you are considering a move to Fedora 4 with RDF, you may want to move to Fedora 4 with XML as a first step and then migrate your XML to RDF

  • Note that much of the mainline Samvera community development is currently focused on leveraging RDF for standard Samvera operations.

    • e.g., Samvera rightsMetadata will be expressed in RDF (you won’t need to think about it, though, because migration tools).

    • Samvera:Works will include RDF support for expressing file:item:work relationships

    • etc.

How many other people are in the Samvera on Fedora 3 boat?

  • Great question! A lot! We’ll do a survey to get details, and post results!

  • It is important and useful for those sites running Samvera on Fedora 3 to communicate their status, plans and issues, so that they can leverage each others’ work in moving to Samvera on Fedora 4 (or supporting Samvera on Fedora 3).

  • This discussion will unfold on the list (and Samvera Tech calls)

  • The Fedora 4 community is soliciting features & issues & case studies for specific migration issues & needs.

When I do migrate to Fedora 4, what will I need to change in my technology stack?

  • You will need to move your Samvera components from a Fedora 3 to Fedora 4 stack.

    • The mainline community development includes a new core gem set for Samvera that supports Samvera on Fedora 4 (Active Fedora n+1, ActiveTriples, support for WebACLs, hydra-head, Samvera-access-controls, Samvera-collections, Samvera-derivatives, Samvera-works, sufia (any others?))

    • Penn State’s Fedora 4 beta pilot includes a working Samvera stack around Sufia on Fedora 4.

    • We anticipate that other Samvera heads (not just Sufia-based) can and will also adapted to work on F4 with the latest core gems.

  • You will need to move your Samvera objects from Fedora 3 to Fedora 4.

    • Fedora 4.1 will include migration tools

    • If you wish to migrate to Fedora 4 in advance of the 4.1 release, some tools are being developed within the Samvera community:

    • expressing Samvera rightsMetadata in WebACLs may emerge as a common migration tool need (perhaps also shared with Islandora and the larger Fedora 4 community).

Which Samvera gem versions work with which versions of Fedora?

As of November 6, 2014

Samvera on Fedora 3.

The Samvera Gem gives the official, known compatible set of Samvera gems that work with each other. See

Samvera Gem  v 7.1

  • This was last updated in July 2014.

  1. active-fedora ~> 7.1.0

  2. blacklight ~> 5.5.1

  3. hydra-head ~> 7.2.0

  4. jettywrapper ~> 1.8.2

  5. nokogiri ~> 1.6.0

  6. nom-xml ~> 0.5.1

  7. om ~> 3.1.0

  8. rails < 5.0, >= 3.2.15

  9. rsolr ~> 1.0.10

  10. rubydora ~> 1.8.0

  11. solrizer ~> 3.3.0

Samvera on Fedora 4.

Until Fedora 4 is released, there are not stable Samvera gems for working on Fedora 4. The best code branches are currently referenced in the sufia Fedora 4 branch’s dependency (see gemfile, below) see


gem 'kaminari', github: 'harai/kaminari', branch: 'route_prefix_prototype'

gem 'sufia-models', path: './sufia-models'

gem 'sass-rails', '~> 4.0.3'

gem 'active-fedora', github: 'projectSamvera/active_fedora', branch: 'fedora-4'

gem 'ldp', github: 'cbeer/ldp'

gem 'hydra-head', github: 'projectSamvera/hydra-head', branch: 'fedora-4'

gem 'Samvera-collections', github: 'projectSamvera-labs/Samvera-collections', branch: 'fedora-4'

gem 'Samvera-derivatives', github: 'projectSamvera-labs/Samvera-derivatives', branch: 'fedora-4'