Article

ASEP: a secure and flexible commit protocol for MLS distributed database systems

Dept. of Comput. & Inf. Sci., Michigan Univ., Dearborn, MI
IEEE Transactions on Knowledge and Data Engineering (Impact Factor: 1.89). 12/2000; DOI: 10.1109/69.895800
Source: IEEE Xplore

ABSTRACT The classical Early Prepare (EP) commit protocol, used in many
commercial systems, is not suitable for use in multi-level secure (MLS)
distributed database systems that employ a locking protocol for
concurrency control. This is because EP requires that read locks are not
released by a participant during their window of uncertainty; however,
it is not possible for a locking protocol to provide this guarantee in a
MLS system (since the read lock of a higher-level transaction on a
lower-level data object must be released whenever a lower-level
transaction wants to write the same data). The only available work in
the literature, namely the Secure Early Prepare (SEP) protocol,
overcomes this difficulty by aborting those distributed transactions
that release their low-level read locks prematurely. We see this
approach as being too restrictive. One of the major benefits of
distributed processing is its robustness to failures, and SEP fails to
take advantage of this. In this paper, we propose the Advanced Secure
Early Prepare (ASEP) commit protocol to solve the above problem,
together with a number of language primitives that can be used as system
calls in distributed transactions. These primitives permit features like
partial rollback and forward recovery to be incorporated within the
transaction model, and allow a distributed transaction to proceed even
when a participant has released its low-level read locks prematurely.
This not only offers flexibility, but can also be used, if desired, by a
sophisticated programmer to trade off consistency for atomicity of the
distributed transaction

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