Internet Suspend/Resume (ISR) is a new approach to mobile computing in which a user's computing environment follows the user through the Internet as he or she travels. Today, when a laptop computer is closed, the user's execution state is suspended to disk. When the user moves the laptop to a new physical location, the user may re-open the laptop, and resume working in the same environment that was active at the time of suspend. The goal of the ISR project is to achieve the same effect without requiring the user to transport physical hardware.
For example, imagine a telecommuter who works from home in the morning and at the office in the afternoon. After completing a morning's work, the user clicks "suspend" on the home machine and begins to travel to the office. While the user is en route, the state of the user's computing environment is also en route, through the network, to the machine in the user's office. When the telecommuter arrives at the office, the office machine is presenting the same environment that the user left at home: the same applications and files are open, the windows are all in the expected places, and the cursor is in the appropriate location.
The capabilities of ISR are realized through a combination of two well-studied technologies: virtual machine technology and distributed files systems.
Virtual machine technology is used to capture the user's computing environment at the time of suspend. This environment consists of the user's operating system, applications, data files, customizations and the current execution state. By leveraging virtual machines, this state is re-instantiated directly on the machine at the resume site. This is not a thin-client approach, all process execution and computation takes place on hardware near the user. Therefore, ISR is able to provide the low-latency interactivity that users have come to expect.
One of the great challenges of ISR is that the state associated with a user's computing environment may be large: tens of gigabytes in size. ISR research at Intel Research Pittsburgh has focused primarily on reducing the time required to move this state through the network. We employ distributed file system technology to manage the transport of this state and have investigated a number of novel techniques for improving the operation of the distributed file system.
For example, the ISR team is currently exploring the augmentation of distributed file systems with Content Addressable Storage (CAS) technology. With CAS technology, users may leverage the storage associated with small devices and nearby computers to improve the performance of the ISR system without sacrificing security or robustness.
In addition to serving mobile computer users, ISR technology may also be of particular interest to Information Technology (IT) departments for medium to large organizations. Leveraging the ISR encapsulation of user state, IT departments may provide enhanced services by centrally managing the computing environments for all the users in the organization. As Internet Suspend/Resume becomes more pervasive, users will find themselves able to access their computing environment from any connected computer.