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. See also DS-1782.
• 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 and DS-1117)

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

• New framework for metadata import from external sources (including an out-of-the-box plugin supporting PubMed, and hopefully more coming soon). This concept was previously only supported in JSPUI. Screencast example: http://screencast.com/t/QBImSGbAUZ.  These features were contributed by @mire. The PubMed metadata import plugin was also contributed by the Netherlands Cancer Institute.
  
  • Framework to support metadata import from external sources: DS-2876
  • PubMed metadata import plugin: DS-2880
• Extensible administrative control panel, allowing institutions to override or customize the tabs in the XMLUI administrative "control panel" (see also DS-2625). This feature was contributed by Jozef Misutka of Lindat.
• Export of XMLUI search results to CSV for batch metadata editing. This feature was previously only supported in JSPUI. See also DS-1262. This feature was contributed by William Welling of Texas A&M

REST API new features

• REST Based Quality Control Reports for collection manager. See also DS-2583. This feature was contributed by Terry Brady of Georgetown University
  • See Metadata Query Report on demo.dspace.org
  • See Collection Filter Report on demo.dspace.org
• Support for all authentication methods via REST (e.g. Shibboleth, LDAP, etc). See also DS-2898.
• New /registries endpoint which provides access to the metadata registries via REST. See also DS-2539. This feature was contributed by Terry Brady of Georgetown University.
• REST API now provides a version via /status endpoint (inherits the version of DSpace API). See DS-2619. This feature was contributed by Ivan Masár.

Search/Discovery enhancements

• All searches now default to boolean AND. See DS-2809. This enhancement was contributed by Andrea Schweer.
• New "Has File" facet, which allows you to easily filter by items that have one or more files. See DS-2648. This enhancement was contributed by Christian Scheible.
• Full text indexing of Excel spreadsheets, so that they are now searchable. See DS-2629. This enhancement was contributed by Ed Goulet.
• Right-to-left text in PDFs is now indexed for searching. See DS-1187. This enhancement was contributed by Saiful Amin 

Other enhancements:

• PDFBox was upgraded to version 2.0 (DS-3035). A new PDFBox Thumbnail generator was also added and enabled by default (DS-3052). These features were contributed by Ivan Masár.
• OAI-PMH was upgraded for compliance with the OpenAIRE 3.0 guidelines for literature repositories. This enhancement was contributed by Pedro Príncipe.

Features Removed or Replaced in 6.0

• The build.properties configuration file has been replaced by an enhanced local.cfg configuration file. The new local.cfg allows you to easily override any configuration (from dspace.cfg or modules/*.cfg files) by simply copying it into your local.cfg and specifying a new value. It also provides enhanced configuration options as detailed in the Configuration Reference documentation. The old build.properties file is no longer used nor supported.
  
  • WARNING: As part of adding this new configuration scheme, many of the configuration settings in DSpace (primarily those in modules/*.cfg files) had to be renamed or prepended with the name of the module. This means that 5.x (or below) configurations are no longer guaranteed to be compatible with 6.x. If possible, we recommend starting with fresh configs (see below), and moving all your locally customized settings into the new local.cfg file.
• The PDF Citation Cover Page configuration file has been renamed (from disseminate-citation.cfg to citation-page.cfg). See this feature's documentation for more details.
• The legacy search engine (based on Apache Lucene) and legacy Browse system (based on database tables) have been removed from DSpace 6.0 or above. Instead, DSpace now only uses Discovery (based on Apache Solr) for all Search/Browse capabilities. See DS-2160. The legacy browse system was removed by Kevin Van de Velde. The legacy search system was removed by Tim Donohue.

• The DSpace Lightweight Networking Interface (LNI), supporting WebDAV / SOAP / RPC API, has been removed from DSpace 6.0 or above. We recommend using REST or SWORD (v1 or v2) as a replacement. However, if you still require it, the old (unmaintained) LNI codebase is still available at https://github.com/DSpace/dspace-lni. This change was contributed by Robin Taylor of University of Edinburgh.

• Support for SRB (Storage Resource Broker) file storage has been removed from DSpace 6.0 or above.  As it was unmaintained (and seemingly unused) for many years, this feature was removed along with its configurations. As a replacement, a new file storage plugin system was added, featuring a traditional local file storage option (default) and an Amazon S3 file storage option (see Storage Layer documentation, especially Configuring the Bitstream Store). For more information on the removal of SRB support, also see DS-3055. This change was contributed by Peter Dietz of Longsight.
• The user groups Administrator and Anonymous cannot be renamed or deleted.  If you had renamed them, they will be renamed back to the stock names during the upgrade. DSpace is now dependent on these specific names due to internal changes. This change was contributed by Mark Wood of IUPUI.
• XPDF PDF Thumbnail generation has been removed. Please use the ImageMagick or PDFBox thumbnail generators instead. See DS-2159. This change was contributed by Mark Wood of IUPUI.
• The default strategy to create new handles for versioned Items has changed. If you have Item Level Versioning enabled and you have versioned Items in your DSpace installation, you may want to change the configuration to continue using the mechanism to create handles as it was in DSpace 4 and 5. You can find more informations here: Item Level Versioning#IdentifierServiceOverride.
• Elasticsearch Usage Statistics feature is deprecated in the 6.0 release. While they still function, and you can continue to use them, in a future DSpace release they will be removed. If you are looking for a usage statistics option, we recommend instead using the default SOLR Statistics engine and/or DSpace's integration with Google Analytics. See DS-2897 for more information.

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