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Distributed Systems Brief Overview

Distributed Systems Brief Overview. CNT 5517-5564 Mobile & Pervasive Computing Dr. Sumi Helal University of Florida. Distributed System Values. Reliability Availability Dependability Security Performance: response time, throughput, etc

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Distributed Systems Brief Overview

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  1. Distributed SystemsBrief Overview CNT 5517-5564 Mobile & Pervasive Computing Dr. Sumi Helal University of Florida

  2. Distributed System Values • Reliability • Availability • Dependability • Security • Performance: response time, throughput, etc • Scalability: vertical (concurrency) and horizontal (distribution) Fault-tolerance

  3. Distributed System Values, cont’d • Consistency • Up-to-date-ness • Adaptability • Reconfigure-ability • Manageability • Extensibility • more

  4. Reliability • Eternal: • Mean Time to Failure (MTTF) • Extended Reliability = Availability • (1) Employing Redundancy (replication) • (2) Employing specific Recovery Procedures • In either (1) or (2): • First detect failure • Second Mask it (redundancy), or Recover from it (recovery)

  5. Availability • Past: • Today: • As past, plus: • Available through a variety of networks • Available through a variety of devices • Available through a variety of locations (e.g., while mobile? ) 4 nine’s = 0.9999

  6. Replication in Distributed Systems • Consider data, how can we use replication of data to increase its availability and use?

  7. Replication Management Protocols

  8. Distributed Systems Intricacies • Synchronization: multiple clocks (difficult to agree on exact time) • Concurrency: multiple simultaneous accesses potentially conflicting. • Failures: high probability of failures (too many components). Complex failure modes (single, multiple simultaneous, network partition, …) • Consensus: difficult to reach consensus (odds includes failures, lack of synchronization, …) • more …

  9. Distributed Computing Models • Client/Server Approach • Multi-tier Approach • Peer-to-Peer Approach • Agent based systems • Mobile Code (Applets, mobile agents, ..) • Service-oriented computing • Service registration/discovery • Service composition • Cloud Computing

  10. The Emerging Computing Model: Cloud, Edge & Beneath • Cheaper to provide services to a thin client than to maintain a fat client in a changing world (service Science) • Besides the Cloud, all other computing infrastructures become simply Edge Devices to the Cloud • Do Sensors count in this new world of Clouds? Are Sensors Edge Devices?

  11. Cloud, Edge & BeneathSensors – to - Cloud

  12. Cloud, Edge & BeneathGateway – to Cloud

  13. Cloud, Edge & BeneathSensors – to – Edge; Edge – to- Cloud In Network Computing Cloud Computing The Case for the Edge

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