Umlaut is an "open source front-end for a link resolver", or:
Umlaut is a just-in-time aggregator of "last mile" specific citation
services, taking input as OpenURL, and providing an HTML UI as well
as an api suite for embedding Umlaut services in other applications.
What the heck does this mean?Read more.
The 3.0 release of Umlaut will not add any new features, but instead modernizes Umlaut's architecture to be based on Rails 3.1+ as an engine gem, and work on modern ruby versions. Lots of unsupported cruft was also removed from the codebase. (Umlaut actually began as a Rails 1.x application!).
Why this matters to you is that Umlaut should be easier to install and maintain than it ever was before. SeeInstallation/Getting Started instructions.
This is still an alpha release at present. It likely has some not yet discovered bugs, missing features, or performance issues. But it should be much easier to work with than Umlaut 2.x, if you are looking to get started with Umlaut, definitely start with the 3.x alpha. Alpha tester feedback very welcome, please let me know of any difficulties you have with it, suggestions, questions, etc.
Umlaut 3.x source code is available in theumlaut3dev branch in the github project