When two competent people disagree about a well-settled technical issue there is a possibility that they are talking at cross purposes.
Consider an inventory record, for concreteness one that contains a count of the number of pairs of size 13EEE black oxfords in some wholesaler's stock, and two programs, A and B. B queries this record, finds that it contains a count of 20 pairs, and withdraws 5 pairs from and updates the record to reflect the new count of 15. After B's query but before but before B's update A also queries this record and withdraws 10 pairs. B updates the record to reflect a new count of 20 pairs. A then updates it to reflect a new count of 10 pairs. In the upshot the inventory record reflects a balance of 10 pairs when it should reeflect a balance of only 5 pairs. Scenarios of this kind that differ only in detail can be multiplied ad infinitum et nauseam. Does either of you judge o that they are innocuous, o that serialization cannot prevent them, or o that such serialization requirements are different for programs having different levels of reusability? John Gilmore, Ashland, MA 01721 - USA ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
