characterizationofdistributedsystems-資料下載頁(yè)
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【導(dǎo)讀】1990年11月，第一個(gè)Web服務(wù)器。Laboratory）正式發(fā)布了Web技術(shù)標(biāo)準(zhǔn)。目前，與Web相關(guān)的各種技術(shù)標(biāo)準(zhǔn)都由著名的。用統(tǒng)一資源定位技術(shù)實(shí)現(xiàn)全球信息的精確。用新的應(yīng)用層協(xié)議實(shí)現(xiàn)分布式的信息共。這三個(gè)特點(diǎn)無(wú)一不與信息的分發(fā)、獲取和利用有關(guān)。"也就是說(shuō)，作為Inter上的一種應(yīng)用。中國(guó)互聯(lián)網(wǎng)絡(luò)信息中心《第十八次中國(guó)互聯(lián)網(wǎng)。截止到2020年6月30日，我國(guó)網(wǎng)民人數(shù)達(dá)到了人，與。1994，MarkAndreessen發(fā)布Netscape，成為當(dāng)。1995,Microsoft開(kāi)始全面轉(zhuǎn)向Inter
【正文】 sical resources ? ., servers support users at most O(n) ? The performance loss ? ., DNS no worse than O(logn) ? Prevent software resources running out ? ., IP address ? Avoid performance bottlenecks ? ., partitioning name table of DNS, cache and replication Failure handling ? Detecting ? . checksum for corrupted data ? Sometimes impossible so suspect, . a remote crashed server in the Inter ? Masking ? . Retransmit message, standby server ? Tolerating ? . a web browser cannot contact a web server ? Recovery ? . Roll back ? Redundancy ? . IP route, replicated name table of DNS Concurrency ? Correctness ? ensure the operations on shared resource correct in a concurrent environment ? . records bids for an auction ? Performance ? Ensure the high performance of concurrent operations Transparency ? Access transparency ? using identical operations to access local and remote resources ? . a graphical user interface with folders ? Location transparency ? resources to be accessed without knowledge of their location ? . URL ? Concurrency transparency ? several processed operate concurrently using shared resources without interference with between them ? Replication transparency ? multiple instances of resources to be used to increase reliability and performance without knowledge of the replicas by users or application programmers Transparency (contd.) ? Failure transparency ? users and applications to plete their tasks despite the failure of hardware and software ponents, ., ? Mobility transparency ? movement of resources and clients within a system without affecting the operation of users and programs, ., mobile phone ? Performance transparency ? allows the system to be reconfigured to improve performance as loads vary ? Scaling transparency ? allows the system and applications to expand in scale without change to the system structure or the application algorithms Summary ? Distributed systems are pervasive ? Distributed puting and resource sharing are primary motivations for constructing distributed systems ? Characterization of Distributed System ? Concurrency ? No global clock ? Independent failures Summary (contd.) ? Challenges to construct distributed system ? Heterogeneity ? Openness ? Security ? Scalability ? Failure handling ? Concurrency ? Transparency
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