Stage 4-1 Instructions

Server Side 基本觀念

  • A server is a computer that interacts with a request we make to the computer

  • For example, whenever we type in "http://www.google.com", we are sending a request to Google's servers to return a website.

  • we can understand networks' effectiveness by measuring things like latency and bandwidth.

Network

  • Is a group of entities(可以是個 organization 、團體、政府之類的) that can communicate, even though they're not all directly connected.

  • Messages go through hops

  • 最早的紀錄，written byHomer，用狼煙通知戰情

每一個點都是 Nodes，第一件事是 Code messages，點亮訊息，we need a way to do routing ，了解路徑，了解經由哪個 nodes（截點）

  • Flooding the net像這個例子，整個都撒出去，也會有同時傳訊息的需求，我們要了解誰在用和傳什麼訊息

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Making a networks

  • Way of encode and interpret messages

  • 一邊編碼，other end 解碼（interpret）

  • Way to route messages

  • Know the next place to send

  • Rules for deciding who gets to use resources

  • 兩個訊息同時傳到同一個地方

    Measuring Networks - 他們兩個很不一樣

    Latency

  • Time it takes message to get from source to destination

  • Measured in milliseconds

  • 1000 milliseconds = 1 seconds

  • 算開始時間和結束時間的差

  • 有什麼辦法可以增快

  • Making the signalling nodes further apart, it takes fewer hops

    Bandwidth

  • Amount of information that can transmitted per unit time

  • unit of information divide by unit of time

  • What's the rate you send information

  • Measured in Mbps

  • Mbps =megabitper second or million bits per second

  • 10的六次方

  • 其實就是在看跑了多少0與1的資料

    Bit

    • Smallest unit of information

    • 使用箱子來比喻，0與1的概念，還提了用兩個問題就能問出箱子的顏色

    Buckets of Bits

    • 有多少種可能？請看圖

    • 2的 N 次方，每多一 bit 就多分一次

    Protocol

    • Gives the rules about how a client(web browser) and a server talk

    • Client send messages in a particular way

    • Client sends a message GET <object>, server sends back a response - content of <object>

    • The protocol we use on the web is HTTP(hypertext transfer protocol), use to talk to server, then you request a document

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