Notification and shared annotations go hand-in-hand. Notification of activity in a shared document system is known to support awareness and improve asynchronous collaboration, but few studies have examined user needs and explored design tradeoffs. We examined large-scale use of notifications in a commercial system and found it lacking. We designed and deployed enhancements to the system, then conducted a field study to gauge their effect. We found that providing more information in notification messages, supporting multiple communication channels through which notifications can be received, and allowing customization of notification messages are particularly important. Overall awareness of annotation activity on software specifications increased with our enhancements.

Annotations are a natural way to record comments and ideas in specific contexts within a document. When people read, they often underline important parts of a document or write notes in the margin. While we typically think of annotating paper documents, systems that support annotating digital documents are becoming increasingly common. Annotations on digital documents are easily shared among groups of people, making them valuable for a wide variety of tasks, including online discussion and providing feedback. This research explores three issues that arise when using annotations for asynchronous collaboration. First, I present the results of using a prototype annotation system, WebAnn, to support online discussions in an educational setting. In a field study in a graduate class, students contributed twice as much content to the discussion using annotations compared to a traditional bulletin board. Annotations also encouraged a different discussion style that focused on specific points in the paper being discussed. The study results suggest valuable improvements to the annotation system and factors to consider when incorporating online discussion into a class. Second, I examine providing appropriate notification mechanisms to support online discussion using annotations. After studying notifications in a large-scale commercial system and finding them lacking, I designed and deployed enhancements to the system. A field study of the new notifications found that overall awareness of annotation activity on software specifications increased with my enhancements. The study also found that providing more information in notification messages, supporting multiple communication channels through which notifications can be received, and allowing customization of notification messages ...