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CSSE 444: Concurrent & Distributed Systems

CSSE 444: Concurrent & Distributed Systems Dr. Yingwu Zhu Office: ENGR 530 Phone: 296-5515 Email: zhuy@seattleu.edu Web: http://fac-staff.seattleu.edu/zhuy Brief Bio PhD in CSE, University of Cincinnati, 2005 MS., BS. in CS, Huazhong University of Science & Technology

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CSSE 444: Concurrent & Distributed Systems

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  1. CSSE 444: Concurrent & Distributed Systems Dr. Yingwu Zhu Office: ENGR 530 Phone: 296-5515 Email: zhuy@seattleu.edu Web: http://fac-staff.seattleu.edu/zhuy

  2. Brief Bio • PhD in CSE, University of Cincinnati, 2005 • MS., BS. in CS, Huazhong University of Science & Technology • MCSE (Microsoft Certified Software Engineer) • 3-year Software Engineer and Project Manager in industry • Publications: papers in top Journals and Conferences • http://fac-staff.seattleu.edu/zhuy • Research: Peer-to-peer(P2P) systems, file/storage systems, distributed systems, networking • Teaching: Data Structures, C/C++, Advanced topics in OS, Concurrent Distributed Systems

  3. What can you learn in this course? • Two main threads: • Basic concepts in distributed systems • Communications, naming, reliability, availability, consistency, security, etc. • Practical projects in network programming (TCP/UDP), http client/server models, processes and threads communications

  4. Syllabus • Access the syllabus on my homepage

  5. OITLNX Account • OITLNX will be the server where you do the programming assignments/projects • If you do NOT have an account, contact HelpDesk ASAP! • Programming related docs in my website

  6. My Questions? • Q1: Do you have experiences in socket programming? • Q2: Do you have experiences in process communications? • Q3: Do you have experiences in thread programming? • Q4: Do you have knowledge in computer networks?

  7. My Office Hours • 1:30-2:30PM MWF • Or Anytime as long as I am in office (Generally I am in office every week day )

  8. Introduction Chapter 1

  9. Definition of a Distributed System (1) • A distributed system is: • A collection of independent computers that appears to its users as a single coherent system. • Two aspects: • Hardware: machines are autonomous • Software: Users think it is a single system

  10. Definition of a Distributed System (2) 1.1 A distributed system organized as middleware.Note that the middleware layer extends over multiple machines.

  11. Goals of Distributed Systems • Connecting users and resources • Access remote resources, e.g., files, printers, etc • Share local resources with other users in a controlled way • Transparency • Hide that fact that processes and resources are physically distributed across multiple computers • Different forms of transparency

  12. Transparency in a Distributed System Different forms of transparency in a distributed system.

  13. Openness • Definition: A system that offers services according to standard rules that describe the syntax and semantics of those services • Interoperability • Portability:

  14. Scalability • How to measure scalability of a system? • By system size: scale to more users and resources added to the system • By geography: geographically scalable in that users and resources are distributed across the Internet • By administration: administratively scalable, spanning many independent administrative organizations

  15. Scalability Problems Examples of scalability limitations.

  16. Scaling Techniques (1) 1.4 • The difference between letting: • a server or • a client check forms as they are being filled

  17. Scaling Techniques (2) 1.5 An example of dividing the DNS name space into zones.

  18. Hardware Concepts 1.6 Different basic organizations and memories in distributed computer systems

  19. Multiprocessors (1) 1.7 • A bus-based multiprocessor.

  20. Multiprocessors (2) 1.8 • A crossbar switch • An omega switching network

  21. Homogeneous Multicomputer Systems 1-9 • Grid • Hypercube

  22. Software Concepts • An overview of • DOS (Distributed Operating Systems) • NOS (Network Operating Systems) • Middleware

  23. Uniprocessor Operating Systems 1.11 • Separating applications from operating system code through • a microkernel.

  24. Multiprocessor Operating Systems (1) monitor Counter { private: int count = 0; public: int value() { return count;} void incr () { count = count + 1;} void decr() { count = count – 1;} } • A monitor to protect an integer against concurrent access.

  25. Multiprocessor Operating Systems (2) monitor Counter { private: int count = 0; int blocked_procs = 0; condition unblocked; public: int value () { return count;} void incr () { if (blocked_procs == 0) count = count + 1; else signal (unblocked); } void decr() { if (count ==0) { blocked_procs = blocked_procs + 1; wait (unblocked); blocked_procs = blocked_procs – 1; } else count = count – 1; } } • A monitor to protect an integer against concurrent access, but • blocking a process.

  26. Multicomputer Operating Systems (1) 1.14 • General structure of a multicomputer operating system

  27. Multicomputer Operating Systems (2) 1.15 • Alternatives for blocking and buffering in message passing.

  28. Multicomputer Operating Systems (3) • Relation between blocking, buffering, and reliable communications.

  29. Distributed Shared Memory Systems (1) • Pages of address space distributed among four machines • Situation after CPU 1 references page 10 • Situation if page 10 is read only and replication is used

  30. Distributed Shared Memory Systems (2) 1.18 • False sharing of a page between two independent processes.

  31. Network Operating System (1) 1-19 • General structure of a network operating system.

  32. Network Operating System (2) 1-20 • Two clients and a server in a network operating system.

  33. Network Operating System (3) 1.21 • Different clients may mount the servers in different places.

  34. Positioning Middleware 1-22 • General structure of a distributed system as middleware.

  35. Middleware and Openness 1.23 • In an open middleware-based distributed system, the protocols used by each middleware layer should be the same, as well as the interfaces they offer to applications.

  36. Comparison between Systems • A comparison between multiprocessor operating systems, multicomputer operating systems, network operating systems, and middleware based distributed systems.

  37. Clients and Servers 1.25 • General interaction between a client and a server.

  38. An Example Client and Server (1) • The header.h file used by the client and server.

  39. An Example Client and Server (2) • A sample server.

  40. An Example Client and Server (3) 1-27 b • A client using the server to copy a file.

  41. Processing Level 1-28 • The general organization of an Internet search engine into three different layers

  42. Multitiered Architectures (1) 1-29 • Alternative client-server organizations (a) – (e).

  43. Multitiered Architectures (2) 1-30 • An example of a server acting as a client.

  44. Modern Architectures 1-31 • An example of horizontal distribution of a Web service.

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