Major Java API refactor, supporting UUIDs and Hibernate. The DSpace Java API has been refactored significantly to make it more modular, and make it easier to achieve future RoadMap modularity goals. For more detailed information, see DSpace Service based api or DS-2701. This feature was contributed by Kevin Van de Velde of @mire, with support/help from the DSpace Committers.

• Hibernate allows us more stability in our database layer (decreases the likelihood of database specific bugs), and potentially allows us to support additional database platforms in the future
• UUIDs provide all objects with stable, globally unique identifiers (instead of existing incremental, non-unique database identifiers). This simplifies the management of identifiers in our object model.
• The Java API itself is now split into three "layers" which are all now initialized via Spring
  
  • Service layer, which contains DSpace business logic
  • Database Access Object (DAO) layer, which contains specific Hibernate database queries to locate/find individual objects
  • Database Object layer, which provides access to specific database columns, object properties via Hibernate

Most sites will not notice this major API refactor, as the upgrade is seamless. However, if you've performed major (Java-level) customizations, you may need to refactor your own customizations to use this newly refactored API. Some examples are on the DSpace Service based api page.

Enhanced (Reloadable) Configuration System. See Configuration Reference, Enhanced Configuration Scheme and DS-2654. This feature was contributed by Tim Donohue of DuraSpace.

• Provides easier management of local configurations via a new local.cfg file. Any configurations (from *.cfg files) can be overridden in DSpace by simply copying them into your local.cfg and changing the value. See Configuration Reference
• Many configurations now automatically reload as soon as you save your local.cfg file. This means you don't need to restart Tomcat every time you need to change a configuration.
  • Please note: Unfortunately, at this time, some configurations do still get cached in the XMLUI or JSPUI (or similar). So, while many will reload, not all of them yet support this feature.

Enhanced file (bitstream) storage plugins, including support for Amazon S3 file storage. This feature was contributed by Peter Dietz of Longsight.

• Configuring the Bitstream Store (also see https://github.com/DSpace/DSpace/pull/1159)

Configurable site healthcheck (i.e. repository status) reports via email. This feature was contributed by Jozef Misutka of Lindat.

• Healthcheck reports (also see DS-2659).

XMLUI new features

REST API new features

• DSpace REST API now includes CRUD (Create/Read/Update/Delete) endpoints, see DS-2168 by the Czech Technical University in Prague

RDF Interface to support Linked (Open) Data (NEW)

• DSpace can now provide its content as Linked (Open) Data via a new RDF interface (provided as an "rdf" webapp), see DS-2061 by Pascal -Nicolas Becker

OAI-PMH interface enhancements / bug fixes

• OpenAIRE v3 compliance (operators over filters)
• OAI respects item READ rights
• /oai displays the list of available contexts; contexts have descriptions

See DS-1649 by João Melo 

Enhanced Thumbnail Quality (disabled by default)

• Enhanced image thumbnails can now be generated using ImageMagick
• Enhanced PDF Thumbnails can now be generated using ImageMagick and Ghostscript

See DS-2105 by Terry Brady with the support of Georgetown University

Bug fixes / improvements to Biblio-Transformation-Engine (BTE)

• BTE: batch import from various bibliographic formats was upgrade to the latest version (see DS-2183)

Kindly contributed by the Greek National Documentation Centre/EKT

Enhancements to DOI Support (disabled by default)

• Enhanced EZID IdentifierProvider Metadata Mapping via XSLT, see DS-2119 by Mohamed Mohideen Abdul Rasheed

Apache Solr libraries were upgraded for all interfaces (JSPUI, XMLUI, and OAI)

See DS-2253 by Roeland Dillen with the support of @mire

Add a place for third-party JARs / plugins to be "found" by DSpace (disabled by default)

• DSpace will now look for JARs / plugins in the locations specified by "plugin.classpath" value specified in dspace.cfg.

See DS-2107 by Mark H. Wood with the support of  IUPUI University Library

All objects now have metadata support

• All DSpace objects (Communities, Collections, Items, EPeople, Groups) now have metadata, and most now use the default "dc" (Dublin Core) metadata schema.
  • NOTE: The only exception is EPeople metadata, which is stored in a new "eperson" metadata schema.
• The User Interfaces don't yet take advantage of this enhancement in DSpace 5.0. Instead, this is an internal restructuring of data within DSpace. In the future, this provides the potential to create more enhanced metadata (or even more configurable metadata) on all objects

See DS-1582 by Mark H. Wood with the support of  IUPUI University Library and Kevin Van de Velde with the support of @mire