CS262B Reading Summary
Managing Update Conflicts in Bayou, a Weakly
Connected Replicated Storage System
Douglas B. Terry et al.
Summary by Feng Zhou
3/8/2004
Strong points of the paper are:
- The application specific conflict detection and resolution are
tenets of the Bayou approach. They are implemented with domain
specific languages and provide the application with control of how
conflicts are defined/detected and resolved. The dependency check
approach supercedes the conventionial version vectors and timestamps
methods and can detect conflicts undetectable by them. The merge
procedure provides mechanisms to support both automatic merge and
manual resolution.
- The two example applications (meeting room scheduler and
bibliographic db) show the strengths of Bayou very well. They emphasize
that the flexibility of Bayou actually reflexes how people normally
work and should be more natural to users for these kinds of
collaborating apps.
One major flaw.
Because Bayou needs to reorder updates, the kinds of updates that
can be supported by Bayou are fundamentally limited. That is,
there are updates that may not make sense once reordered. And
even for reorderable updates, they have to be recorded using logical
log records instead of physical logging, so that they can be
reordered. It would be good if the paper can point out where are
these limitations and how they impact the applications that can be
built on top of Bayou.