This page contains an initial requirements analysis for the Item Level Versioning Support, contributed to DSpace 3.0. Refer to the official DSpace 3 documentation for the most up to date information on Item Level Versioning. |
DSpace Item Level Versioning Support is a funded open source activity to bring work done by NESCent and @mire into the DSpace 3.0 Codebase. Additional partners have signed onto this activity to assure that resources are available to drive Item Versioning Support forward and make it available to the larger DSpace community in the next release.
Key Stakeholders involved with Item Versioning Support:
The history of an item should be available, and it should be possible to cite a particular version of the item.
General user actions that would generate a new Version of a new Item and their overal impact on creation of a new DSpace item.
With a full feature versioning capability on Items, we may possibly be able to support restoration of Item Versions through an interface such as this WIKI page example interface.
An example of an initial Version within Dryad
An example of a second version within Dryad
[TODO]
Past Architectural Review Group work on the DSpace Data Model and versioning focused its research and recommendations on replicating the entire DSpace Item contents when a new DSpace Item was created in DSpace. This means that all item metdata and content would be replicated. This was done to ease the complexity of managing references across individual Items to the content and metadata that would be considered the same across those versions.
In the GSoC project to address versioning, we made an effort to optimize on the above situation and emplyed the following strategy for the production of a New version of a DSpace Item
For every new Version a separate DSpace Item will be created that replicates the metadata and bundle records to allow multiple Items to share references to existing bitstreams that do not change across versions.
For every new version of an Item, a Bundle will be created and the Bundle will link to all the preexisting bitstreams for the original Item. This means that Bitstreams may be associated with more than one Item by being linked by Bundle.
The versioning support in Dryad is based on replicating DSpace Item, MetadataValue and Bundle Records, creating an identical version of all Metadata and Bitstream relationships. The new version of the Item “conserves” Bitstream Contents by reusing references to the persisted Bitstreams across individual Item Revisions.
The Bitstream deletion logic in DSpace is enhanced to support detecting if the Bitstream is no longer a member of any Item Revisions before being flagged as deleted.
DSpace Item Versioning will be encapsulated as an Extensible Service that may be reimplemented by the local repository maintainers to produce alternate versioning behaviors and Identifier Schemes. Versioning Services layer on top of IdentifierServices dedicated to Encoding, Resolution, Minting and Registration of Identifiers for specific DSpace Items and Bitstreams. It is through this highly extensible layering of functionality where local developers can alter the versioning behavior and introduce their own local enhancements. The DSpace Service Manager, based on the Spring Framework, provides the key leverage for this flexibility.
The Versioning Service will be responsible for the replication of one or more Items when a new version is requested. The new version will not yet be preserved in the Repository, it will be preserved when the databases transactional window is completed, thus when errors arise in the versioning process, the database will be properly kept in its original state and the application will alert that an exception has occurred that is in need of correction.
The Versioning Service will rely on a generic IdentifierService that is described below for minting and registering any identifiers that are required to track the revision history of the Items.
Dryad Example: Version 1, Version 2 of same document (see versions listed at bottom of page)
Code: Google Code
public interface VersioningService { Version createNewVersion(Context c, int itemId); Version createNewVersion(Context c, int itemId, String summary); void removeVersion(Context c, int versionID); void removeVersion(Context c, Item item); Version getVersion(Context c, int versionID); Version restoreVersion(Context c, int versionID); Version restoreVersion(Context c, int versionID, String summary); VersionHistory findVersionHistory(Context c, int itemId); Version updateVersion(Context c, int itemId, String summary); Version getVersion(Context c, Item item); } |
The Identifier Service maintains an extensible set of IdentifierProvider services that are responsible for two important activities in Identifier management:
Dryad Example: The same document can be accessed via different identifiers: DOI link (http://dev.datadryad.org/resource/doi:10.5061/dryad.1385.2), Handle link (http://dev.datadryad.org/resource/info:hdl/10255/dryad.36265), default DSpace Link (http://dev.datadryad.org/resource/10255/dryad.36265)
Code: Google Code
public interface IdentifierService { void reserve(Context context, Item item) throws AuthorizeException, SQLException, IdentifierException; String register(Context context, Item item) throws AuthorizeException, SQLException, IdentifierException; DSpaceObject resolve(Context context, String identifier) throws IdentifierNotFoundException, IdentifierNotResolvableException; void delete(Context context, Item item) throws AuthorizeException, SQLException, IdentifierException; } |
public abstract class IdentifierProvider { protected IdentifierService parentService; protected ConfigurationService configurationService; @Autowired @Required public void setConfigurationService(ConfigurationService configurationService) { this.configurationService = configurationService; } public void setParentService(IdentifierService parentService) { this.parentService = parentService; } public abstract boolean supports(String identifier); public abstract String register(Context context, DSpaceObject item) throws IdentifierException; public abstract String mint(Context context, DSpaceObject dso) throws IdentifierException; public abstract DSpaceObject resolve(Context context, String identifier, String... attributes) throws IdentifierNotFoundException, IdentifierNotResolvableException;; public abstract void delete(Context context, DSpaceObject dso) throws IdentifierException; } |
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd"> <bean class="org.dspace.identifier.HandleIdentifierProvider" scope="singleton"/> <bean class="org.dspace.identifier.InternalIdentifierProvider" scope="singleton"/> <bean class="org.dspace.identifier.IdentifierServiceImpl" id="org.dspace.identifier.IdentifierService" autowire="byType" scope="singleton"/> </beans> |
Addons Can easily add additional Providers without directly needing to alter DSpace Code
See Dryad Specific Identifier and Versioning Services
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd"> <bean class="org.dspace.versioning.DryadPackageVersionProvider" autowire="byType"/> <bean class="org.dspace.identifier.DOIIdentifierProvider" scope="singleton"/> </beans> |
The IdentifierProviders are also responsible for altering any existing DSpace metadata fields that need to be altered on the new and previous items to record the relationship between Item Versions.
Dryad supports a unique identifier resolving service based on Spring WebMVC which allows Identifiers registered within the IdentifierServices to be dereferenced to varied representations of the actual DSpace Items. This resolution can span dspace to alternative webapplications to support various representation formats. The mechanism is extendable in the XMLUI and will be utilized to support dereferencing identifiers via content negotiation to expose alternative format representations of the Item, in Dryad the following are currently implemented.
http://dev.datadryad.org/resource/doi:10.5061/dryad.r460n.2
http://dev.datadryad.org/resource/info:hdl/10255/dryad.39114
http://dev.datadryad.org/resource/10255/dryad.39114
http://dev.datadryad.org/resource/doi:10.5061/dryad.r460n.2/citation/ris
TY - DATA ID - doi:10.5061/dryad.r460n.2 T1 - Data from: Testing embargo AU - Feinstein E( Y1 - 2012/04/30/ JF - Testing journal PB - Dryad Data Repository UR - http://dx.doi.org/10.5061/dryad.r460n.2 DO - doi:10.5061/dryad.r460n.2 ER - |
http://dev.datadryad.org/resource/doi:10.5061/dryad.r460n.2/citation/bib
@misc{dryad_r460n_2, title = {Data from: Testing embargo}, author = {Feinstein, E(}, year = {2012}, journal = {Testing journal}, URL = {http://dx.doi.org/10.5061/dryad.r460n.2}, doi = {doi:10.5061/dryad.r460n.2}, publisher = {Dryad Digital Repository} } |