A CSCW framework for the flexible coupling of groupware widgets

Modern CSCW (computer supported cooperative work) applications are driven by intensive graphical user interfaces. Groupware widgets such as shared scrollbars and text editors are common in these applications to facilitate synchronization of shared information across a user group. These widgets differ from their single-user counterparts in that they must coordinate and consistently reflect changes in shared widget properties. We propose a framework allowing these groupware widgets to be transformed from their single-user counterparts. The framework enables single-user widgets to register their connections to a separate notification server. After registration, these widgets become groupware widgets. The notification server uses the registered connections to update widgets of the changes in shared properties using a callback mechanism. Widget designers only need to determine the set of properties by which a group of widgets should be synchronized and to what extent they are synchronized. These properties collectively define the coupling among a group of widgets. The coupling is kept as a coupling portfolio in the notification server. Dynamic modification of coupling portfolios is supported by on-the-fly reconfiguration of multicast groups. Our framework is useful to simplify the client implementation of handling synchronization events and reduce the overheads of processing these events. These concepts are illustrated using a groupware Web browser.