In the previous parts, I wrote about two "back-office" open source applications (and tangentially discussed a few others) that are well-established in their communities and can support a wide variety of repository services. While it may be philosophically important that these are open source applications, I would argue that the next parts, in which I want to talk about services and applications on top of the repository infrastructure, are the more crucial and benefit tremendously from the ability to create and customize interfaces for specific use cases to the full extent necessary by anyone with a fairly broad skill-set. Blacklight grew out of a next-generation library catalog interface, and while it still has very firm roots in the library world, it is also being used for archives, digital collections, and institutional repository interfaces. It is also an open source application, based on the Ruby on Rails framework. Out of the box, it is a fairly generic interface to a solr index (with a little sprinkling of optional MARC data) and some relatively benign application features (users, bookmarks, saved searches). Connecting it to our existing Solr index is fairly trivial, and just requires some little configuration changes: 
config[:index_fields] = {
    :field_names => [
      "dc.description",
      "dc.creator",
      "dc.publisher",
      "dc.subject",
      "dc.date",
      "dc.format"
    ],
    :labels => {
      "dc.description"           => "Description:",
      "dc.creator" => "Creator:",
      "dc.publisher" => "Publisher:",
      "dc.subject" => "Subject:",
      "dc.date" => "Date:",
      "dc.format" => "Format:"
    }
  }
Which gives you a very basic discovery interface into your collection. Extending Blacklight to work with Fedora is also easy, so in less than 50 lines of code, I had full access to the Fedora web services APIs and SPARQL interface. Adding management interfaces was also simple, using normal Ruby of Rails techniques and with less than 500 lines of code, a passable repository manager interface was available and I could import assets and metadata. Adding a security layer on top of the repository content is also easy, thanks to the work the UPEI team put into the DrupalServletFilter, which allows Fedora to authenticate users against any SQL database. Because of this, we can use the XACML policy language built into Fedora to do record-level security (which I confess, I don't entirely understand, however, it is an enormously powerful and expressive language if you like XML verbiage). For storing re-use rights, I am very intrigued by the Open Digital Rights Language, which can integrate with Fedora and Blacklight to express non-object-security rights (re-use, segmentation, etc) using my proof-of-concept ruby-odrl. With these fundamentals in place (ingest services, security policies, and resource discovery), one can build more advanced services on top of the repository, like collections, batch and on-demand conversion/transcode services, export/transfer services (one-click "export to PBS COVE"?) -- and, because this can be done as rails plug-ins, they are readily sharable outside of this single application and provide templates for others to continue to develop and extend similar services to evolving platforms. Because setting up a Blacklight application is so painless, it would be easy for public broadcasting institutions to create custom-made (yet shareable) modules and views for specific purposes (news, productions, archiving, etc) that all share the same back-end infrastructure yet offer users an easy way to interact with their data in a way that makes sense for their work. As I mentioned in my Fedora article, you aren't limited to data you control and have locally, but can bring in data from external sources (say, pulling in metadata from the NPR API or an RSS feed from a stock footage house) and present it both coherently and cohesively. I'm looking for a good source of freely available test data, and I would rather not invest too much time building a corpus of archival assets if there is something already existing. The biggest challenge I'm having is finding comprehensive metadata, but the closest I've come are some podcast feeds from sources like Democracy Now!, however that doesn't capture the breadth of materials I'd like to demonstrate. Finally, a couple requisite screen-shots now that there is something visual to work with, using the default Blacklight theme with some quick interface hacks. [gallery]