<p> CHAPTER 1: INTRODUCTION</p><p>CHAPTER OUTLINE</p><p> System Definitions  Hardware Concepts  Software Concepts  Client/Server Model</p><p>System Definitions</p><p>Traditional Uniprocessor Operating Systems</p><p> Resource Manager (system’s view) – processor, information, memory, device  Extended Machine (user’s view) – virtual concepts</p><p>With goals: efficiency, flexibility, robustness</p><p>Recent Technological Advances</p><p> Widespread low-cost high-performance PCs  High-speed network interconnection</p><p>Emerging Applications</p><p> Concurrent/parallel  Distributed  Collaborative</p><p>Distributed Systems to Support New Applications</p><p> (user’s view) – Transparency: a single computer view of multiple computer systems  (system’s view) – Distributions: decentralized/autonomous, cooperative/collaborative Unique Problems (Limitations) in Distributed Systems</p><p> lack of global state information  lack of global clock (or time)  failures of system components (processors, communication networks)</p><p>Transparency - access, location, migration, relocation, replication, concurrency, failure, persistence</p><p>Interoperability – interface, standard, openness, separation of model/policy/mechanism</p><p>Middleware – organization for implementation of distributed systems</p><p> Models – file, communication (RPC), object  Layers – system, application</p><p>Underlying Operating Systems for Distributed Systems</p><p> Distributed Operating Systems – transparency for multiprocessor and homogeneous multiple computer systems  Network Operating Systems – interoperability/portability/openness for heterogeneous systems and networks</p><p>Additional goals: </p><p> Scalability – size, geographical distance, administrative complexity – asynchronous communication, distribution, caching  Robustness – security, reliability, privacy – cryptographic schemes, fault-tolerance, dispersion Hardware Concepts</p><p>Shared Memory Multiprocessor Systems</p><p> Bus – tightly coupled  Switched – cross-point, interconnection network (e.g., Omega network), etc.</p><p>Homogeneous Multiple Computer Systems</p><p> Bus – tightly/loosely coupled (through message passing)  Switched – grid, cube, interconnection network – routing</p><p>Emulating Shared-Memory in Message-Passing Systems (DSM)</p><p> Migration  Replication  Thrashing and false sharing</p><p>Message Passing Heterogeneous Multiple Computer Systems </p><p> Networks</p><p>Software Concepts</p><p>Major Issues in Uniprocessor OS</p><p> Virtual machine  Multi-level protection (mode)  Minimum kernel (microkernel)</p><p>Additional Issues in Multiprocessor DOS</p><p> Multiprocessor scheduling  Synchronization – semaphore, monitor, and etc. Additional Issues in Multiple Computer DOS</p><p> Communication primitives – send/receive – naming, buffering and blocking  Distributed synchronization  Relationship between synchronization and communication</p><p>Major Issues in Network OS (NOS)</p><p> Network protocols for interoperability  Network services – remote access and resource sharing – telnet, ftp, smtp, http, nfs</p><p>More Issues for Distributed Processing in Network Environment</p><p> Remote execution and process migration  Load sharing and balancing  Collaborative/cooperative application</p><p> MIDDLEWARE-BASED DISTRIBUTED SYSTEMS</p><p>Middleware: scalability and openness of NOS and transparency of DOS</p><p> Services: locating services, group management, authentication/authorization, etc.  Communication: reliable multicast, atomic transaction, etc.</p><p>Middleware Models</p><p> NFS  RPC  Distributed Objects  Distributed Documents Client/Server Model</p><p> Interaction > communication > access resource > request/reply  Dumb/thin/heavy weight client  Vertical distribution: user interface/application server/database server  Horizontal distribution: parallelizing servers  Parallelizing clients: P2P</p><p>Some Emerging Computing Paradigms</p><p> Ubiquitous/pervasive computing  Mobile agent-based computing  Mobile/wireless computing  Grid computing  P2P computing</p>