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Unformatted text preview: ed algorithms. Can we use something like this to solve the whiteboard example? Always deliver packets in the same total order (defined by Lamport clock). Will this work? Even if all nodes are awake and working, need to wait to display until ping neighbors, since you might get a message from B that depends on A, but you haven’t seen A yet. Painful, since most of the time, no one else is editing the same part of the whiteboard as you are. GUI design principle: always allow user to edit (AJAX). How do we do that while preserving correctness (whiteboards do not stay out of synch)? Keep timestamped log of all edits to whiteboard. Can apply changes in timestamp order. If an “old” update comes in, insert in log and redraw. Paper uses example of mutual exclusion. Correctness: one at a time everyone in order of request Liveness: (in absence of failures: if every holder releases it) eventually get the lock Implementation: Every message timestamped with value of logical clock. 1) multicast request...
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- Spring '14