DSpace Users Group - Jan 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

DSpace Users Group - Jan DSpace As A Platform Agenda –DSpace Plugin Mechanism Introduced in version 1.4 –Example Application: Custom HTTP interface for the WRLC Digital Object Catalog

DSpace Users Group - Jan Plugin Manager Plugin: Independently “pluggable” software component PluginManager: Java class that organizes/selects/creates plugins Plugin Interface: Defines a class of service Plugin Implementation: Service provider

DSpace Users Group - Jan 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

DSpace Users Group - Jan 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

DSpace Users Group - Jan 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

DSpace Users Group - Jan 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

DSpace Users Group - Jan 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 # IngestPackageServlet –Invokes a named PackageIngester –Patch to be submitted soon

DSpace Users Group - Jan Digital Object Catalog DSpace IngestPackageServlet DisseminatePackageServlet DIDL Ingester PluginURL Ingester PluginEAD Ingester Plugin DIDL Disseminator Plugin HTML Disseminator Plugin Bitstream Disseminator Plugin DCEditorDCMS Web siteEAD XForms DCEditorImgViewerXMLViewer HTTP POST HTTP GET or POST DOC Web site webui

DSpace Users Group - Jan Dissemination Interface

DSpace Users Group - Jan 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 –Can’t post XML content with plain HTML Alternatives include: JavaScript (e.g. the XMLHttpRequest class) Browser plugin (e.g. XForms viewer)

DSpace Users Group - Jan Submission Response What is the proper response to an ingestion request? –Successful => submission receipt If ingestion plugin also implements the DisseminationPackage interface, IngestPackageServlet will use it for response –Unsuccessful => detailed error message PluginException thrown to servlet

DSpace Users Group - Jan Ingestion Interface

DSpace Users Group - Jan Ingestion Interface

DSpace Users Group - Jan 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

DSpace Users Group - Jan Web Services Applications Integration with content-specific workflow applications –E.g. ETD-db DLF-Aquifer “asset actions” Pathways “interoperability fabric” obtain, harvest & put services

DSpace Users Group - Jan For More Information... Presentation write-up: Wiki pages: /CrosswalkPlugins /PackagerPlugins Me: