Computer Science 425 Distributed SystemsAdministrative AdministrativeAdministrativeAdministrativePlan for Today Our First Aim in this Course was… (first lecture)….Can you name some examples of Distributed Systems?FOLDOC definition (Free On-line Dictionary Of Computing)Textbook definitionsA working definition for usProblems we have Seen and Solved Since ThenProblems we have Seen and Solved in this ClassProblems we have Seen and Solved in this ClassProblems 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)A range of Challenges for Designers of Distributed SystemsWhat we Have Learned Since ThenFinal Exam InformationFinal Exam MaterialFinal Exam Problem Types: Multiple ChoiceCalculation and Algorithmic ProblemsDiscussion and Trade-Off ProblemsDesign ProblemsComparison ProblemsCourse EvaluationThank YouLecture 28-1Computer Science 425Distributed SystemsLecture 28 “Wrap-Up”Klara NahrstedtLecture 28-2Administrative • MP3 posted– Deadline December 7 (Monday) – pre-competitionin cs216 SC» Top five groups will be selected for final demonstration on Tuesday, December 8– Demonstration Signup Sheet for Mondaydemonstrations – sign up online on the websiteLecture 28-3Administrative• MP3 - Tuesday, December 8 Final Competition– Start at 2pm in 216 SC – Competition goes between 2-5pm– Groups will be informed on Monday, December 7 by 6pm about the results (email and website)– Each group starts with power point presentation and follows up with the demonstration of the features – Competition Criteria: » presentation clarity, » demonstration of features, » explanation of features during demonstration, » response to questions, » stability of demonstration – Final results from the competition will be announced at 5pm in 216 SC – so please come all !!!Lecture 28-4Administrative• MP3 - Documentation due by December 9 – Email URL link to Ying (TA) with all your project descriptions (see next slide for project template description link)– Readme file must include:» Boot-straping routine – how one install your system – developers manuscript» How one use your system – usage prescription for users» Known bugs, what are the issues with your system/application – Tar or zip your source code and upload it to agora wiki» URL Information will be provided on the web/in class/on newsgroup– Fill out project template as specified» Template Information will be provided on the web/in class/on newsgroupLecture 28-5Administrative• MP3 instructions for Project Documentation Preservation– Here's the template page for cs425 students to copy and fill out.https://agora.cs.illinois.edu/display/mlc/cs425-TemplateProject• Website only cs425 students and instructors can access to post the template page and also upload attachmentshttps://agora.cs.illinois.edu/display/mlc/cs425-fa09-projectsLecture 28-6Plan for Today • Brief review what this course was all about• Information about the Final Exam – Room, time, grading, etc. • Short examples of final exam problems• ICES – course evaluationLecture 28-7Our First Aim in this Course was…(first lecture)….To Define the Term Distributed SystemLecture 28-8Can you name some examples of Distributed Systems?• Client-server (e.g., NFS)• The Internet• The Web• An ad-hoc network• A sensor network• DNS• Napster, Gnutella, Fast-track (peer to peer overlays)• Any other?Lecture 28-9FOLDOC definition (Free On-line DictionaryOf Computing)A 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.Lecture 28-10Textbook 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]Lecture 28-11A 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• [Is this definition still ok, or would you want to change it?]• What Evidence/Examples have we seen?(First lecture slide)Lecture 28-12Problems 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 Routing protocols (RIP, OSPF)Lecture 28-13Problems 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 Routing – RIP, OSPFBasic Theoretical ConceptsBridge to SystemsWhat Lies BeneathLecture 28-14Problems we have Seen and Solved in this Class• RPCs & Distributed Objects • Transactions • Concurrency Control• Distributed Transactions • Replication Control• Distributed File Systems • Ubiquitous / Mobile Systems• Security• The GridBasic Building BlocksDistributed Services(e.g., databases)Distributed Apps that people use directlyComputational Facilitythat scientists use directlyNecessary propertiesLecture 28-15Problems 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 – InternetCore Material of this courseRelated to CS 525Related to CS
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