DSpace As A Platform

1
DSpace As A Platform

• Creating Custom Interfaces With
• Content Packaging Plugins
• Don Gourley
• Washington Research Library Consortium
• DSpace User Group, Open Repositories 2007
• Session 5

2
DSpace As A Platform

• Agenda
• DSpace Plugin Mechanism
• Introduced in version 1.4
• Example Application Custom HTTP interface for
  the WRLC Digital Object Catalog

3
Plugin Manager

• Plugin Independently pluggable software
  component
• PluginManager Java class that organizes/selects/c
  reates plugins
• Plugin Interface Defines a class of service
• Plugin Implementation Service provider

4
Types Of Plugins

• Singleton Plugin One implementation of the
  class
• Sequence Plugins Ordered set of implementations
• Named Plugin Multiple available implementations
• Names bound to implementation in config
• Self-named

5
Plugins in DSpace 1.4

• AuthenticationMethod
• Sequence plugins (implement a stack)
• E.g. Password, LDAP
• MediaFilter
• E.g. HTML, Word, PDF, JPEG
• BitstreamDispatcher
• E.g. by Item or least-recently checked

6
Metadata Content Plugins

• DisseminationCrosswalk and IngestionCrosswalk
• E.g. DC, QDC, MODS, METS, PREMIS
• XSLT define crosswalk with stylesheet
• PackageDisseminator and PackageIngester
• E.g. METS, PDF

7
Invoking Plugins

• Plugin Consumer Java class that uses
  PluginManager
• Configure plugin classes, names, options in
  dspace.cfg
• Reload Web app for online consumers
• E.g. AuthenticationManager
• Run command-line program
• E.g. Packager, MediaFilterManager,
  ChecksumChecker
• Invoke via OAI-PMH PluginCrosswalk

8
Invoking Plugins

• Need a mechanism for invoking content packaging
  plugins with HTTP GET and POST requests
  (REST-style Web services)
• DisseminatePackageServlet
• Invokes a named PackageDisseminator
• Patch 1442299
• IngestPackageServlet
• Invokes a named PackageIngester
• Patch to be submitted soon

9
Digital Object Catalog
DCEditor
DCMS Web site
EAD XForms
HTTP POST
IngestPackageServlet
DIDL Ingester Plugin
URL Ingester Plugin
EAD Ingester Plugin
DSpace
webui
DIDL Disseminator Plugin
HTML Disseminator Plugin
Bitstream Disseminator Plugin
DisseminatePackageServlet
HTTP GET or
POST
DCEditor
ImgViewer
XMLViewer
DOC Web site
10
Dissemination Interface
11
Submitting Ingestion Content

• IngestPackageServlet requires an HTTP POST
  request
• DOC plugins generally expect XML
• Must be done by browser if you want the DSpace
  session cookie for login context
• Cant post XML content with plain HTML
  Alternatives include
• JavaScript (e.g. the XMLHttpRequest class)
• Browser plugin (e.g. XForms viewer)

12
Submission Response

• What is the proper response to an ingestion
  request?
• Successful gt submission receipt
• If ingestion plugin also implements the
  DisseminationPackage interface,
  IngestPackageServlet will use it for response
• Unsuccessful gt detailed error message
• PluginException thrown to servlet

13
Ingestion Interface
14
Ingestion Interface
15
Issues With HTTP Interfaces

• Security
• DOC plugins use DSpace public API
• Access controlled by authorization system
• Sometimes need to override (e.g. recreating
  structural metadata bitstream)
• Performance
• Comparable to native interfaces
• Functionality
• Limited to content packaging plugins

16
Web Services Applications

• Integration with content-specific workflow
  applications
• E.g. ETD-db
• DLF-Aquifer asset actions
• Pathways interoperability fabric obtain,
  harvest put services

17
For More Information . . .

• Presentation write-up
• http//dspace.wrlc.org/doc/wrlc/DSpaceAsAPlatform.
  pdf
• Wiki pages
• http//wiki.dspace.org/index.php/PluginManager
• 
  /CrosswalkPlugins
• 
  /PackagerPlugins
• Me gourley_at_wrlc.org