Checkpoints of GUI-based Applications

We describe a new system, called guievict, that enables the graphical user interface (GUI) of any application to be transparently migrated to or replicated on another display without premeditative steps such as re-linking the application program binary or re-directing the application process's window system communication through a proxy. Guievict is based on a small X window server extension that enables an application to retrieve its window session, a transportable representation of its GUI, from the window server and a library of GUI migration functionality that is injected in the application process at run time. We discuss the underlying technical issues: controlling and synchronizing the communication between the application and the window system, identifying and retrieving the GUI resources that form the window session, regenerating the window session in a new window system, and maintaining application transparency. We have implemented guievict for the XFree86 implementation of the X window system. The GUI migration performance of guievict is measurably but not perceptibly worse than that of a proxy-based system.