What I Know So Far About

Upgrading from Fedora 3 to 4

Adam Wead

Penn State University

awead@psu.edu / @amsterdamos

May the Fedora 4 be with you...

• Currently in beta
• Final release expected by year-end
• Upgrade tools coming out with 4.1 release

Who's Doing It Now?

• Fedora4 beta pilots
  • Art Institute of Chicago
  • Penn State University
  • UC - San Diego
• At present, only Penn State has existing Fedora3 repository

Fedora at Penn State

• Repository storage for ScholarSphere and ArchiveSphere
• Both are Sufia-based
• 4775 objects / 37GB data in ScholarSphere
• 72262 objects / 186GB data in ArchiveSphere
• Looking to start migrating ScholarSphere at year-end
• ArchiveSphere to follow after that

When I say Migrate...

• Update Fedora to version 4, move data from a Sufia+Fedora3 repository to a Sufia+Fedora4 repository
• Some details are due to Sufia's design
• Most details will apply to any Fedora-based application

Upgrade Overview

1. Upgrade to latest hydra-head 7 with latest Fedora 3.x
2. Make some decisions
   • any RDF translations?
   • version strategy?
   • object relationships?
   • intermediate nodes?
3. Iterate over your Fedora3 repository, ingesting objects and versions into Fedora4
4. Verify

@noreply says you need to bang your head against it

Upgrading First

• Upgrading to latest Fedora (3.8?) helpful but not required
• Hydra updates are optional, but recommended
• If migrating from an older Hydra, be aware of changes to models and datastreams
• Example: ActiveFedora 7 now uses ActiveTriples for RDF datastreams

Decisions, Decisions, Decisions

Decisions: Descriptive Metadata Changes

Take advantage of native RDF in Fedora4

class FedoraThreeModel < ActiveFedora::Base
  has_metadata "descMetadata", MyDatastream
  has_attributes :title, datastream: :descMetadata
end
    			

becomes

class FedoraFourModel < ActiveFedora::Base
  property :title, predicate: RDF::DC.title do |index|
    index.as :stored_searchable, :facetable
  end
end
					

If MyDatastream is an ActiveFedora::NtriplesRDFDatastream under AF7, then easy, if not, you'll need to do some RDF translation.

Decisions: Non-RDF Datastreams

• XML datastreams are still supported via OM
• No special treatment during migration
• Best for storing generated XML
• Only transfer versions unless absolutely necessary

Decisions: Versions

• Versions have to be explicitly created during migration
• Original Fedora3-assigned dates have to be preserved elsewhere
• ActiveFedora tracks object and datastream versions separately
• No object-level versions in ActiveFedora at this time

Decisions: Relationships

1. Parent/child hierarchies of nodes
   • direct mapping of RELS-EXT in Fedora3
   • fixed points in the hierarchy with attached properties
   • currently supported in ActiveFedora 8
2. Modeshape's weak references
   • allows you to make associations to nodes that don't exist
   • solves a particular use case in Sufia (batch edits)
   • currently not supported in ActiveFedora 8

Decisions: Intermediate Nodes

In Fedora4, every object must have a parent, even if you have a million objects and one parent

• this causes performance issues due to Modeshape's behavior
• need to resize the hierarchy with additional levels of nodes
• we don't care about the these nodes
• Sufia's solution: create intermediate nodes based on the noid
  • an object with an id of 12ab34cd
  • gets a hierarchy of nodes /12/ab/34/cd/12ab34cd
  • depends on how your objects are identified
  • specific to Sufia and not in ActiveFedora

The Upgrade Process

Getting from 3 to 4: Using Hydra

• there is no ActiveFedora that does Fedora3 and Fedora4
• access Fedora3 using the rubydora gem
• utilize Hydra, with ActiveFedora 8, to converting/ingest data into Fedora4

Getting from 3 to 4: Without Hydra

1. Using a Fedora3 connector
   • Fedora4 accesses the Fedora3 API (readonly)
   • this might be the option provided in 4.1
2. Don't use Hydra? Use it anyway!
   • you can still use rubydora
   • express your models and datastreams using ActiveFedora
   • use Hydra to migrate the data to Fedora4
   • you don't have to keep using Hydra

Plan of Attack

• Work with DCE to complete AF8/Fedora4/Sufia integration
  • rightsMetadata RDF conversion
  • model BatchEdit with weak references or (strong) references?
  • reconfig audit process
• Work with Duraspace on migration strategies and modeling decisions
• Communicate progress to and elicit feedback from the Hydra community at-large
• Circulate documentation and the tools that result from our work
• Be the first guinea pig to help pave the way for future migrations

Thank You

Adam Wead

Penn State University

awead@psu.edu / @amsterdamos