Group Annotations in NCSA Mosaic


Mosaic supports group annotations -- annotations to documents anywhere on the network that are shared by multiple people in a group.

This capability is intended to support workgroup collaboration -- relatively small, relatively local groups of people working together on a common problem on the Internet. The idea is that such a group will run a local group annotation server (or just annotation server). Each time a member of the group accesses a document anywhere on the Internet, the annotation server is contacted to find out if any members of the group have posted annotations on that document; if so, hyperlinks to the annotations (served by the annotation server) are interleaved into the document text -- just like with personal annotations. Annotations (both text and video) can be posted via the normal Mosaic annotation interface, by selecting "Workgroup Annotations" from the appropriate option menu.

The NCSA Public Annotation Server

We have developed an annotation server (which has been released as part of the NCSA httpd version 0.4; see here). We are running it on an NCSA system for public access by the Mosaic/World Wide Web community, and we encourage anyone who is interested to configure their Mosaic setups to use it, to post annotations on it, and to read annotations others have posted.

To tell your Mosaic about the public annotation server, put the following line in your .Xdefaults file:

If you do not have a fairly fast network link to the NSFnet backbone, you may experience performance degradation within your Mosaic session when you have this resource set, as the annotation server at NCSA is being contacted each time you access a document. On the plus side, we're sitting right on the backbone and running the server on a very fast system.


There is no security in place: anyone may edit or delete annotations that anyone else posts. This means two things:

The current annotation server is a proof of concept. We are planning to address the larger issues involved with a practical, trustable system down the road.

Design Issues

There are a number of unresolved design issues involving group- and community-wide annotation servers. We'd love to hear your ideas -- feel free to leave a group annotation with your comments or questions! Discussion, summaries, etc. of some of these issues will be here.