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Distributed Computing
CMSC 433, March 27th
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Is distributing computing
different?
• What kinds of distributed computing
environments exist?
• Ways in which distributed computing is
different
– Addressing objects
– Latency
– Partial failure
– Concurrency
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Distributed computing
environments
• Usually refers to multiple CPU’s
• Shared address space or message passing?
• On same chip, in same room, or across the
internet?
– Latency, failure modes
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Existing environments
• Seti @ Home
• Server for search engine
• My laptop, PDA, cell phone, MP3 player
and digital camera
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Types of failure
• Machine sleeps
– wakes up, recovers state
• Machine crash or failure
– machine may reboot and rejoin
• Network partition
– network may heal
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Uniform view of distributed
objects
• Some objects are remote, some are local
– Doesn’t really matter to user of object
– Objects might transparently migrate
• Design doesn’t have to take object
distribution into account
• Failure and performance issues don’t belong
in the design
• The interface doesn’t change if an object is
remote
