When you point to a text or graphics link, the arrow-shaped pointer changes to a hand-shaped ____.

Which of the symbols below means “zero or more, without limit”?

a) 0..* b) 0.. c) 0,1,2,… d) -1..*

Phase 1 of the Extended Two-Phase Commit Protocol is identical to Phase 1 of the two-phase commit protocol we have described. Phase 2 of the extended protocol is as follows:

Phase Two. If the coordinator received at least one “aborting” vote during Phase 1, it decides to abort, deallocates the transaction record from its volatile memory, sends an abort message to all cohorts that voted “ready,” and terminates the protocol. If all votes are “ready,” the coordinator enters its uncertain period, forces a willing to commit record (which contains a copy of the transaction record) to its log, and sends a commit message to each cohort. Note that the transaction is not yet committed. If a cohort receives an abort message, it decides to abort, rolls back any changes it made to the database, appends an abort record to its log, releases all locks, and terminates. If a cohort receives a commit message, it decides to commit, forces a commit record to its log, releases all locks, sends a done message to the coordinator, and terminates the protocol. The coordinator waits until it receives the first done message from a cohort. Then it decides to commit, forces a commit record to its log, and waits until it receives a done message from all cohorts. Then it writes a completion record to its log, deletes the transaction record from its volatile memory, and terminates. Describe timeout and restart procedures for this protocol. Showthat this protocol blocks only when the coordinator and at least one cohort crash (or a partition occurs) or when all cohorts crash. Give an example where the transaction aborts even though all cohorts voted “ready.” What will be an ideal response?