計(jì)算機(jī)網(wǎng)絡(luò)與分布式系統(tǒng)(編輯修改稿)
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【文章內(nèi)容簡(jiǎn)介】 ed file systems distributed shared memory Time amp。 coordination shared data services (distributed transactions amp。 concurrency control, recovery) highly available services(replication amp。 security fault tolerance) Chapter 1 Introduction to Distributed Systems ? Review of puting history ? Why should we develop distributed system ? Key characteristics of distributed system Review of puting history ? Physically distributed hardware ? Logically centralized software The trend of hardware The need for logically centralized software 1960s amp。 1970s: timesharing system 1980s: personal puter amp。 personal workstation 1990s: distributed puter systems ? User’s requirement: a system built out of large numbers of powerful PCs or workstations but which act together in a coherent way that is as easy to use amp。 understand as an old fashioned timesharing system. ? Role of a new generation operating system(DOS): 2022s: mass distributed systems ., Web OS, Cluster OS Review of puting history 1960 s 1970 s 1980 s 1990 s 2022 s c y c l e s : e x pe r i e n c e r e qui r e m e n t e x pe r i e n c e r e qu ir e m e n t e x pe r i e n c e r e q uir e m e n tK e y i de a s : T im e s h a r ing W or ks tati o n s C om p u ter open , s c a l a bl e , Gr a phi c s a s pe r s on a l c l i e n t s e r v e r f a ul t to l e r a n t I n ter n e t amp。 we b m as s s ys t e m too l s s y s te m Ne twor kin g L A N M il e M I T C T S S Xe r ox Al to B e r ke l e y U nix S tanf or d : V s y s te m NC S A: M os a i c , M E M E X ? s ton e s : C a m br id g e T S S App l e Ⅱ E t h e r n e t, R ing NF S , C M U : a ndr e w I E , Ne ts c a pe ， Unix S m a ll ta l k C a m br i d g e DC S Am oe ba S e a r c h E ngi neS y s t e m O r g a n i z a t i o n N e t w o r k C o m p u t e r s D a t eX e r o x D F S X e r o x P A R C E t h e r n e t amp。 I n t e r n e t X e r o x A l t o 1977C a m b r i d g e D C S C a m b r i d g e U n i v . C a m b i d g e R i n g L S I 4 , M 6 8 0 0 0 1979L o c u s U C L A E t h e r n e t V A X , I B M P C 1980A p o l l o D o m a i n A p o l l o C o m p u t e r s T o k i n g R i n g A p o l l o 1980V s y s t e m s t a n f o r d U n i v . E t h e r n e t V A X , S u n 1982A c c e n t C M U E t h e r n e t V A X , S u n 1982A r g u s M I T 1983A m o e b a V r i j e U n i v . E t h e r n e t V A X , M 6 8 0 0 0 1984N F S S u n Mi c r o s y s t e m s E t h e r n e t V A X , S u n + o t h e r s 1985M a c h C M U E t h e r n e t V A X , S u n + o t h e r s 1986N O W B e r k e l e y M y r i n e t S U N + S o l a r i s 1995D a w n i n g 2 0 0 0 N C I C e t h e r n e t , f a s t e t h e r n e t ,M y r i n e t ( o r m e s h )P o w e r P C + A I X 1998Figure Milestones in Distributed Systems Why should we develop distributed system Most important reason is that application is a starting point and end result of development of distributed systems. Many puter applications occur in a distributed or decentralized environment. ? Sharing expensive resources ? Exchange data between systems The interface between users and Computers is more friendly LAN amp。 Inter applications stimulate DOS’s development ? It’s the software, not the hardware that determines whether a system is distributed or not Examples of distributed systems and applications Distributed UNIX: ? Berkeley BSD UNIX+NFS+NIS ? Amoeba, Mach, Chorus Proliferation of low cost and high performance PCs or Workstations Commercial applications ? airline seat reservation and ticketing ? automatic teller machine Reliability, security Wide area work applications ? Inter, ARPA 100= 1 million ? Inter information service,such as Email, Web, search engine, BBS, Emerce、 digital library Cluster system ?IBM SP2 ?Berkeley’s NOW ?NCIC’s Dawning superserver Meta Computing ? idle puters are ubiquitous Multimedia information access and conferencing application ? continuous media service, such as VOD servers, video phone and video conference, their main requirement is quality of service ? ATM, real time OS, continuous media servers Key characteristics of distributed system What’s the Distributed System? Definition 1: A distributed system is one in which there exists a multip licity of interconnected processing resources able to cooperate under systemwide control on a single problem with minimal reliance on centralized procedures, data or hardware. — Formulated by the anizing mittee for the 1st conf. on DCS Definition 2: A Distributed system consists of a collection of autonomous puters linked by a puter work and equipped with distributed system software — From our textbook Resource Decentralization and sharing Some or all of the puting resources should be decentralized in function
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