Computer Science 425 Distributed SystemsOur First Aim in this Course was…(first lecture)….Can you name some examples of Distributed Systems?What is a Distributed System?FOLDOC definitionTextbook definitionsA working definition for usProblems we have Seen and Solved Since ThenProblems we have Seen and Solved in this ClassSlide 10Slide 11Problems we have Seen and Solved in this Class (and relation to other courses)Problems we have Seen and Solved in this Class (and relation to other courses)Problems we have Seen and Solved in this Class (and relation to other courses – old course numbers)A range of Challenges for DesignersWhat we Have Learned Since ThenQuestions?Slide 18Etc.Slide 20Course EvaluationThank You 2002, M. T. Harandi and J. Hou (modified: I. Gupta) Lecture 28-1Lecture 28-1Computer Science 425Distributed SystemsComputer Science 425Distributed SystemsLecture 28 (Part 2/2)“Wrap-Up” 2002, M. T. Harandi and J. Hou (modified: I. Gupta) Lecture 28-2Lecture 28-2Our First Aim in this Course was…(first lecture)….Our First Aim in this Course was…(first lecture)….To Define the Term Distributed System(First lecture slide) 2002, M. T. Harandi and J. Hou (modified: I. Gupta) Lecture 28-3Lecture 28-3Can you name some examples of Distributed Systems?Can you name some examples of Distributed Systems?•Client-server (e.g., NFS)•The Internet•The Web•An ad-hoc network•A sensor network•DNS•Kazaa (peer to peer overlays)•(Society?)•(Food Chain?)(First lecture slide) 2002, M. T. Harandi and J. Hou (modified: I. Gupta) Lecture 28-4Lecture 28-4What is a Distributed System?What is a Distributed System?(First lecture slide) 2002, M. T. Harandi and J. Hou (modified: I. Gupta) Lecture 28-5Lecture 28-5FOLDOC definitionFOLDOC definitionA collection of (probably heterogeneous) automata whose distribution is transparent to the user so that the system appears as one local machine. This is in contrast to a network, where the user is aware that there are several machines, and their location, storage replication, load balancing and functionality is not transparent. Distributed systems usually use some kind of client-server organization.(First lecture slide) 2002, M. T. Harandi and J. Hou (modified: I. Gupta) Lecture 28-6Lecture 28-6Textbook definitionsTextbook definitions•A distributed system is a collection of independent computers that appear to the users of the system as a single computer [Andrew Tanenbaum] •A distributed system is several computers doing something together. Thus, a distributed system has three primary characteristics: multiple computers, interconnections, and shared state[Michael Schroeder] (First lecture slide) 2002, M. T. Harandi and J. Hou (modified: I. Gupta) Lecture 28-7Lecture 28-7A working definition for usA working definition for usA distributed system is a collection of entities, each of which is autonomous, programmable, asynchronous and failure-prone, and communicating through an unreliable communication medium.•Our interest in distributed systems involves –design and implementation, maintenance, study, algorithmics•Entity=a process on a device (PC, PDA)•Communication Medium=Wired or wireless network•What Evidence/Examples have we seen?(First lecture slide) 2002, M. T. Harandi and J. Hou (modified: I. Gupta) Lecture 28-8Lecture 28-8Problems we have Seen and Solved Since ThenProblems we have Seen and Solved Since Then•Time and Synchronization•Global States and Snapshots•Multicast Communications •Mutual Exclusion •Leader Election •Impossibility of Consensus•Failure Detectors •Peer to peer systems – Gnutella and Chord•Networking – Internet Internals (DNS; Routing protocols – RIP, OSPF) 2002, M. T. Harandi and J. Hou (modified: I. Gupta) Lecture 28-9Lecture 28-9Problems we have Seen and Solved in this ClassProblems we have Seen and Solved in this Class•Time and Synchronization•Global States and Snapshots•Multicast Communications •Mutual Exclusion •Leader Election •Impossibility of Consensus•Failure Detectors •Peer to peer systems – Gnutella and Chord•Networking – Internet Internals (DNS; Routing protocols – RIP, OSPF)Basic Theoretical ConceptsBridge to SystemsWhat Lies Beneath 2002, M. T. Harandi and J. Hou (modified: I. Gupta) Lecture 28-10Lecture 28-10Problems we have Seen and Solved in this ClassProblems we have Seen and Solved in this Class•Midterm•HW’s and MP’s–A new peer to peer application!How to get good grades(and regrades, and jobsin some cases) 2002, M. T. Harandi and J. Hou (modified: I. Gupta) Lecture 28-11Lecture 28-11Problems we have Seen and Solved in this ClassProblems we have Seen and Solved in this Class•RPCs & Distributed Objects •Transactions •Concurrency Control•Distributed Transactions •Replication Control•Distributed File Systems •Distributed Shared Memory •Security•The GridBasic Building BlocksDistributed Services(e.g., databases)Distributed Apps that people use directlyEasy programmingComputational Facilitythat scientists use directlyNecessary properties 2002, M. T. Harandi and J. Hou (modified: I. Gupta) Lecture 28-12Lecture 28-12Problems we have Seen and Solved in this Class(and relation to other courses)Problems we have Seen and Solved in this Class(and relation to other courses)•Time and Synchronization•Global States and Snapshots•Multicast Communications •Mutual Exclusion •Leader Election •Impossibility of Consensus•Failure Detectors •Peer to peer systems – Gnutella and Chord•Networking – Internet Internals (DNS; Routing protocols – RIP, OSPF)Core Material of this courseRelated to CS 525Related to CS 438 2002, M. T. Harandi and J. Hou (modified: I. Gupta) Lecture 28-13Lecture 28-13Problems we have Seen and Solved in this Class (and relation to other courses)Problems we have Seen and Solved in this Class (and relation to other courses)•RPCs & Distributed Objects •Transactions •Concurrency Control•Distributed Transactions •Replication Control•Distributed File Systems •Distributed Shared Memory •Security•The GridCore Material of this courseRelated to CS 411/CS 511Related to CS 423/CS 523Related to CS 523Related to CS 525Related to CS 421/CS 433 2002, M. T. Harandi and J. Hou (modified: I. Gupta) Lecture 28-14Lecture 28-14Problems we have Seen and Solved in this Class (and relation to other courses – old course
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