I just discovered another annotation project very similar to mine. HyLighter is a web highlighting and annotation research prototype for use in education. First developed in 2001, with annotation added in 2004, it shares the key features of my implementation: it allows users of IE and Firefox to highlight passages of text and associate text annotations.

There are, however, a number of differences:

  • HyLighter allows users to compare what they have highlighted with what others have highlighted, using colors to indicate who has highlighted what and shades to show how many users have highlighted a passage.
  • In my system, all of a users annotations are shown in a margin, each lined up with the associated highlighted passage of text. With HyLighter, the user must click on the highlighted passage to retrieve the annotation, and the notes are not lined up.
  • HyLighter allows users to see all the annotations (by all users) associated with a passage of text. My system only shows all the annotations by a single user at one time.
  • My system allows users to make their annotations public or private. In HyLighter I believe all annotations are public.
  • My annotation system is open source; HyLighter is not. Even the demo requires registration (I haven’t tried it).
  • HyLighter is a stand-alone application. My system, in contrast, is Web-aware and is designed to be easily integrated into other web applications. I have integrated it with Moodle and provided instructions for doing the same with other applications. Most of my code is in the Javascript front end, where it is independent of the web application; the back end can be extremely small (in the static demo it’s just an XML file). HyLighter, on the other hand, has a Java back end with administration features; I suspect it also has much more of its implementation code in the back end.
  • HyLighter associates annotations with documents. Mine associates them with URLs and document fragments – mine appears to be more web-ready (I could be wrong). I also export annotations as an Atom feed.
  • I have a smartcopy feature which adds context information to quotes created with copy and paste.

Their research agenda is also different: they focus on how students highlight, both to measure student learning and to improve students’ ability to select key passages of text. They also suggest using HyLighter as an alternative to threaded forums.

By contrast, I recommend against using annotation as a substitute for forum posts, and have endeavored to keep the system focused on annotation. Our research interest (that of the TextWeaver team) is in enabling students to construct (weave) richer dialogs, using annotation and smartcopy to reference other parts of a discussion (hence the focus on forums rather than documents).

Anyway, it’s all very interesting. I’m somewhat disappointed to discover I am not in fact unique, and surprised that all my searching the web for other systems didn’t turn this up before now. I only discovered HyLighter because it showed up in a search I subscribe to of all blogs mentioning web annotation. I suspect the reason for this can be traced to the fact that the HyLighter team has not open-sourced their software. Which is a shame, really.