DiscoTech: a plug-in toolkit to improve handling of disconnection and reconnection in real-time groupware

Disconnection and reconnection are common problems for users of synchronous groupware, but these problems are not easy for developers to handle because of the wide range of scenarios and timeframes that must be considered. We have developed a new toolkit called DiscoTech that helps programmers deal with disconnection. The toolkit is based on five design dimensions that determine how stored information can be manipulated as the system waits for an absent user to rejoin, and how information should be replayed upon reconnection. DiscoTech provides a plug-in architecture to handle a wide variety of behaviours that developers may need during disconnection; these plug-ins range from fully generic tools to customized strategies with full knowledge of the groupware application. We present the design of the DiscoTech toolkit, show examples of its use, and provide evidence that it covers a broad range of situations, imposes minimal performance overhead, and is easy for programmers to learn. DiscoTech handles a wider range of issues than previous toolkits, without requiring undue effort, and provides a practical way to improve the real-world usability of synchronous groupware.