Facebookcomdocsmobileandroidbuild network time service

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Unformatted text preview: er- to- peer hbp://en.wikipedia.org/wiki/Peer- to- peer Inter- Applica)on Communica)on •  Need a way to send and receive messages •  Inter- process communica)on •  Need naming, rou)ng, transport •  Transport using TCP and UDP –  On top of IP Server Client Applica)on Protocols •  Messages between processes, typically encapsulated within TCP or UDP •  Need agreement between –  Sending process –  Receiving process From: hbp://developers.facebook.com/docs/mobile/android/build/ Network Time Service Client- server or peer- to- peer? 1. Laptop Server 1. Atomic clock facility Protocol Timing Diagram t4 t5 Time ? 1400 t1 Processing Delay t2 Transmission t3 Delay Time Propaga)on Delay t0 Cloud- based File Backup Applica)on •  •  •  •  Client- server or peer- to- peer? Where do the applica)ons run? Who/how to run these applica)ons? What messages are exchanged? 1. 2. 3. Laptop Server 1. 2. 3. From: hbp://developers.facebook.com/docs/mobile/android/build/ Using TCP/IP •  How can applica)ons use the network? •  Sockets API. –  Originally from BSD, widely implemented (*BSD, Linux, Mac OS X, Windows, …) –  Higher- level APIs build on them •  Aher basic setup, much like files One could test network protocols with r/w on a file Client Server File System Calls •  Problem: how to access resources other then CPU –  Disk, network, terminal, other processes –  CPU prohibits instruc)ons that would access devices –  Only privileged OS kernel can access devices •  Kernel supplies well- defined...
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This note was uploaded on 01/27/2014 for the course COSC 4377 taught by Professor Staff during the Spring '08 term at University of Houston.

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