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CS 134
Assignment 2 (Hints (Server -> Time map (Keeps track of last…
CS 134
Assignment 2
Viewservice
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Switching views
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Acknowledgements
The view service may not proceed from view X to view X+1 if it has not received a Ping(X) from the primary of view X
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High level
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Jobs
If the current primary or backup becomes dead, the viewservice selects a server to replace it.
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Primary
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Primary Failure
If the primary fails, the viewservice will promote the backup to be primary.
Goal
Use primary/backup replication, assisted by a view service that decides which machines are alive.
The view service allows the primary/backup service to work correctly in the presence of network partitions.
The view service itself is not replicated, and is a single point of failure.
Backup
Backup Failure
If the backup fails, or is promoted, and there is an idle server available, the viewservice will cause it to be the backup.
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Hints
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Tick function
your viewservice needs to make periodic decisions, for example to promote the backup if the viewservice has missed DeadPings pings from the primary.
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