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TRANSACTION CONTROL EXPRESSIONS (TCEs)

TRANSACTION CONTROL EXPRESSIONS (TCEs). Ravi Sandhu. Transactions Transaction sagas Transaction control expressions (TCEs) Transient versus persistent objects Automated transaction sagas. OUTLINE. TRANSACTIONS. USERS. TRANSACTIONS. DATABASE. Data abstraction and internal consistency.

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TRANSACTION CONTROL EXPRESSIONS (TCEs)

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  1. TRANSACTION CONTROL EXPRESSIONS (TCEs) Ravi Sandhu

  2. Transactions Transaction sagas Transaction control expressions (TCEs) Transient versus persistent objects Automated transaction sagas OUTLINE

  3. TRANSACTIONS USERS TRANSACTIONS DATABASE Data abstraction and internal consistency

  4. Abstract operations credit, debit Serializability interleaved execution is equivalent to a serial execution Failure atomicity either all or none of the actions of a transaction actually take effect TRANSACTIONS

  5. 1. A clerk prepares the voucher 2. The voucher is approved by a supervisor 3. A clerk issues the check TRANSACTION SAGAS

  6. prepare • clerk; approve • supervisor; issue • clerk; prepare • Alice; approve • supervisor; issue • clerk; prepare • Alice; approve • Bob; issue • clerk; prepare • Alice; approve • Bob; issue • Carl; TRANSACTION CONTROL EXPRESSIONS (TCEs)

  7. Dynamic separation of duties Hierarchical roles Substitution of attribution TCEs

  8. Purchasing Clerk Receiving Clerk HIERARCHICAL ROLES Supervisor Clerk

  9. prepare • clerk; 3: approve • supervisor; issue • clerk; prepare • clerk; 3: approve • supervisor=1, manager=2; issue • clerk; VOTING

  10. prepare • clerk; if value > 1000 then 3: approve • supervisor else 1: approve • supervisor; issue • clerk; VALUE BASED APPROVAL

  11. publish • scientist; approve • security-officer & approve • patent-officer; release • librarian; MULTIPLE APPROVAL

  12. requisition • project-manager ; prepare • clerk; agree • project-manager ; approve • purchasing-manager; issue • clerk; ANCHORS

  13. 1. A clerk prepares the voucher and assigns an account 2. The voucher and account are approved by a supervisor 3. A clerk issues the check debiting the account as a side effect Voucher -- transient object Account -- persistent object TRANSIENT vs PERSISTENT OBJECTS

  14. Transactions are executed on persistent objects only as a side-effect of executing transactions on transient objects TRANSIENT vs PERSISTENT OBJECTS

  15. TRANSIENT vs PERSISTENT OBJECTS USERS TRANSACTIONS TRANSIENT OBJECTS PERSISTENT OBJECTS Limited separation of duties Strict separation of duties Distributed audit trail Data abstraction and internal consistency

  16. open • supervisor; {credit • clerk + debit • clerk}; close • supervisor; open • Alice; {credit • clerk + debit • clerk} ; close • supervisor; open • Alice; {credit • clerk + debit • clerk} ; close • Bob; TCEs FOR PERSISTENT OBJECTS

  17. 1. A clerk program prepares the voucher and assigns an account 2. The voucher and account are approved by a supervisor program 3. A clerk program issues the check debiting the account as a side effect AUTOMATED TRANSACTION SAGAS

  18. Transactions Transaction sagas Transaction control expressions (TCEs) Transient versus persistent objects Automated transaction sagas SUMMARY

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