Transaction processing is an established technique for the concurrent
and fault- tolerant access of persistent data. While this technique has
been successful in standard database systems, factors such as
time-critical applications, emerg- ing technologies, and a
re-examination of existing systems suggest that the performance,
functionality and applicability of transactions may be substan- tially
enhanced if temporal considerations are taken into account. That is,
transactions should not only execute in a "legal" (i.e., logically
correct) man- ner, but they should meet certain constraints with regard
to their invocation and completion times. Typically, these logical and
temporal constraints are application-dependent, and we address some
fundamental issues for the man- agement of transactions in the presence
of such constraints. Our model for transaction-processing is based on
extensions to established mod- els, and we briefly outline how logical
and temporal constraints may be ex- pressed in it. For scheduling the
transactions, we describe how legal schedules differ from one another in
terms of meeting the temporal constraints. Exist- ing scheduling
mechanisms do not differentiate among legal schedules, and are thereby
inadequate with regard to meeting temporal constraints. This provides
the basis for seeking scheduling strategies that attempt to meet the
temporal constraints while continuing to produce legal schedules.