Download chapter 1: introduction

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