Other resources follow Moore's law, while battery technology doubles 5-10 years, well below the Moore's technological growth curve. Limited resources argue for reliance on static servers Variable connectivity argues for autonomy Want to perform useful work while disconnected, classic example is taking laptop on vacation or airlplane. Laissez-faire policy, application handles adaptation. The advantage is no new system support is needed. The disadvantage is duplication of work, and no arbitrator exists to resolve incompatible resource demands of competing applications.
Nothing can enforce limits on resource usage.
Application transparent policy. The advantage is that it is backwards compatible with existing applications, but there exist cases in which adaptation by the system is useless or even counter-productive. This approach tries to marry the benefits of the previous two. The system can still arbitrate resources between competing applications, but it is up to the application to determine how best to adapt in terms of the resources offered by the system. Because we need to hide the latency, low bandwidth, and variability of mobile link, clients sometimes need to emulate the functions of the server.