In the ubiquitous computing model there are often many computers running many services. Users will expect that interactions with any given device will be shared with any other device. Services must be able to share information and use other services on the same device and across other devices. In addition it is likely than many services are going to be running at any given time, both on a single device and across many. These services need to be able to interact in real-time. For example, if you are watching television and a news story is mentioned, the user should be able to read it in more detail in a news service on any other device they are using. All this should happen without the user needing to search for it the news story. This sort of seamless interaction between multiple services and devices will allow users to easily and naturally carry on with whatever activity they are doing without needing to work at the device to make it do what they want it to do. This will make the computers invisible to users by making users think of the computers as an entirely different class of device. From the example the user perceives a television and perhaps a phone and not two computers with different interfaces.

'''Service interruption and resumption'''

Ubiquitous computing aims to integrate itself into everyday life, and everyday life is not a single threaded linear event. In the daily lives of an average user, there are many interruptions, stoppages, and unexpected occurrences. Users also need to take breaks during their activities, or even want to put an activity on hold. Sometimes an activity can be put on hold for long durations or permanently. Regardless of the durations or the frequency of interruptions to an activity, the ability to resume an activity after an interruption must exist. Users also expect the service to resume the activity with all previous progresses intact. What this means is that when a service pauses an activity or process it must save all progress done on the activity and any settings that might be created for the activity. When the activity resumes all the saved data must be readily available, and the activity should resume as if no interruption had occurred. Furthermore, when an activity had been paused for a long duration, the user might forget previous progress and the service should be aware of the passage of time, and reacquaint the user with the activity and its progress. In addition, users also require continuously available services, as today’s paradigm move toward the infusion of ubiquitous computing into our everyday lives, the services provided will need to become constantly available, always interrupted and easily resumed. The manner of the service resumption is also paramount in the successful integration of ubiquitous computing. The service must be able to start in one location, paused, resumed at a completely different location with a different interface and a different computer. Only when all of those capabilities are meet, then true integration into ubiquitous computing will be possible, and accepted by the users.