A Programming Interface for Application-Aware Adaptation in Mobile Computing

Brian D. Noble, Morgan Price, M. Satyanarayanan, CMU

One-line summary: API for negotiating with server to get one of k fixed representations of an object; extensions to Unix FS to add datatypes and a cache manager for the server. "Static GloMop".

Overview/Main Points

Applications can track changes in bandwidth, latency, disk space, CPU, power, money (collectively, its "environment"); and adapt to changes
App can request to be notified of changes in specific attributes
App makes policy-change requests (datatype specific!) to server
Unix FS extended by adding type info (at the volume level--gack); group of same typed volumes is a codex
Generic cache manager (viceroy) is a control point for managing type-specific cache managers (wardens). Viceroy is like proxy FE.
Wardens implement standard and datatype-specific access methods and policies, based on datatype.
E.g. QuickTime warden has SwitchTracks operation which implements policy change.
GRASS warden provides access to logical (Unix) files on servers, and has a notion (not well explained) of "quality" level.

Relevance

Obvious.

Flaws

Static rather than dynamic (Satya says on-the-fly processing is "an optimization"); a festival of terminology; extensions to Unix FS are evil. Odyssey is about what you'd expect from a FS-centric group.

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