Annotation Engine
The Annotation Engine is a set of Perl scripts and a database that allows readers anywhere to add comments to web pages anywhere else. The comments, URL, and location pointers are stored in the database here, enabling the Annotation Engine to add them to a page before it is displayed. The engine does not copy the remote web page itself, only adds its extra information to the HTTP stream when it is called to proxy a page.
It is clearly time to add some new text to this page to create space for new annotations. Since notes are fixed to text strings, rather than referring to a numerical position, the existing notes on paragraphs below this one will remain properly placed in context. Thus the Annotation Engine supports persistent annotation even as the annotated document is updated. (If a note suggests a revision, however, and that revision is made-- changing the annotation point-- it makes sense for the note to disappear or move to the "orphaned" section at the bottom of the page.)
The Annotation Engine is a tool in development. One anticipated use will be in connection with online and classroom courses. Teachers may use the engine to mark selections of web pages as recommended or required reading, and students may add notes for themselves or the class. It is also being used in the Openlaw forums for commentary and revision of working drafts.
Annotation is now being added to some of the Berkman Center's streaming multimedia presentations, as yet another way participants can interact online. Anyone with a web browser is invited to join the discussion.
Unlike Third Voice, this engine does not require a browser plugin. It is a server-based proxy. On the downside, it is rather slow in its current incarnation.
The Annotation Engine is an open source project. The source code in progress is available here. It requires Perl, mySQL, the LWP::UserAgent package, and some patience, as it's still not polished to even beta release form.