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Distributed Systems

Distributed Systems. Spring 2004 Ikjun Yeom. Syllabus. Instructor: Ikjun Yeom Email: yeom@cs.kaist.ac.kr Phone: 3544 Office: Room no. 4406 Computer Science Bldg. Class hour: Monday/Wednesday 1:00 - 2:30 PM Office hour: One hour after class

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Distributed Systems

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  1. Distributed Systems Spring 2004 Ikjun Yeom

  2. Syllabus • Instructor: Ikjun Yeom • Email: yeom@cs.kaist.ac.kr • Phone: 3544 • Office: Room no. 4406 Computer Science Bldg. • Class hour: Monday/Wednesday 1:00 - 2:30 PM • Office hour: One hour after class • Course URL: http://cnlab.kaist.ac.kr/~ikjun/ds2004/ds2004.html

  3. Syllabus • Text books • Distributed Systems: concepts and design authored by G. Coulouris et al. • Distributed Systems principles and paradigms authored by A. Tanenbaum and M. Stten • Collection of papers • Grading policy • Final exam. - 20% • Term project – 30% • Presentation – 15% • There will be one or more paper presentation. • Participation - 15% • You should ask at least five questions. • To get your score, please remind me via email after the class. • Paper summary – 20% • You should read the paper before each class and submit at least twenty summary reports. • The report should include the strength and the weakness of the paper.

  4. Tentative class schedule • Lectures – Introduction to distributed systems (1-6 week) • Student presentation (7-14 week) • Final exam. (15 week) • Term project final report presentation (15 – 16 week) • Term project schedule • Proposal due (the end of March) • First draft due (the end of April) • Final report due (the end of May)

  5. Course Contents • Distributed shared memory • Process migration • Load sharing • Time, order and agreement • Remote procedure call • Replication • Fault tolerance • Authentication and security • Mobile computing • Peer-to-peer systems

  6. Distributed Systems • A system in which hardware or software components located at networked computers communicate and coordinate their actions only by passing messages. • Properties: • Concurrency • No global clock • Independent failures • Examples of distributed systems • Internet, Intranet, Mobile and ubiquitous computing

  7. intranet % % ISP % % backbone satellite link desktop computer: server: network link: A Typical Portion of the Internet

  8. A Typical Intranet

  9. Portable and Handheld Devices

  10. Distributed vs. Centralized Systems • Advantages of distributed systems: • Reliability • Sharing of resources • Aggregate computing power • Openness/Scalability • Disadvantages of distributed systems: • Security • Software • Communication network

  11. Challenges (1/3) • Heterogeneity • Networks • Computer hardware • Operating systems • Programming languages • Openness • Open systems are characterized by the fact that their key interfaces are published. • Open distributed systems are based on the provision of a uniform communication mechanism and published interfaces for access to shared resources.

  12. Challenges (2/3) • Security • Scalability • Scalable if will remain effective when there is a significant increase in the number of resources and the number of users. • Failure handling • Detecting failures: checksum, etc. • Masking failures: retransmission, mirroring. • Tolerating failures: Internet telephony • Recovery from failures: checkpoint and rollback recovery.

  13. Challenges (3/3) • Concurrency -> consistency • Transparency • Access transparency • Location transparency • Concurrency transparency • Replication transparency • Failure transparency • Mobility transparency • Performance transparency • Scaling transparency

  14. Client invocation result Server Client Key: Process: Computer: System Architectures (1/2) A Client-server model With multiple servers

  15. System Architecture (2/2) Web proxy server Peer-to-peer

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