3191932525 Distributed Software Programming Lecture 1 Week 1

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31919/32525 Distributed Software
ProgrammingLecture 1 (Week 1)

• 1. Introduction to Networks
• 2. UNIX Programming (Part 1)

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1. Introduction to Networks

• Networking Medium
• Network Topology
• Access Method
• Networks Switching Style
• Networks Service
• Networking Models
• Transparency, Client-Server and OSI

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Networking Medium

• Networking is the interconnection of
  workstations, peripherals terminals and other
  devices.
• Medium forms the communication path
• Networking media include twisted pair, coaxial,
  and fiber-optic cable.
• costs, distance, how much data and how fast the
  data can travel determine the type of networking
  media to use
• Signal can be transmitted over networking media
  using either digital or analog techniques.

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Network Topology

• It is the physical structure of a network
• Bus
• Ring
• Star
• Extended star

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Access Method

• Rules to determine who may transmit on the path
  or channel
• Three common methods
• centralized polling one node acts as a master
• decentralized polling
• contention used with broadcast networks

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Network Switching Style

• Circuit-switched network
• a dedicated path between sending and receiving
  nodes
• Message-switched network
• may not have direct path between sender and
  receiver
• Packet-switched network
• message is segmented into smaller units

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Network Services

• Modes of services
• connection-oriented provides reliable, sequenced
  delivery of data
• connectionless provides simple data-transfer
  facility. No guarantee data units will arrive at
  the destination

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Transparency Model

• Hide the presence of the network.
• Remote file systems (RFSs) make files on remote
  machines appear as if the files were stored on
  the local machine
• Distributed application is a special case of a
  networked application

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Client-Server Model

• Server machines provide services to client
  machines
• Clients make requests
• Servers perform the services

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OSI Model

• Divides a network into seven layers
• application, presentation, session, transport,
  network, data link and physical layers
• The lower layer provides services to the upper
  layer.
• The only physical communication is at physical
  layer.

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OSI Model (contd)

• Data link layer is divided into two sublayers
  LLC and MAC
• MAC mediates access to the medium
• LLC provides connected-oriented and
  connectionless interfaces for network layer
• Network layer is divided into SNICP, SNDCP and
  SNAcP

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2. UNIX Programming (part 1)

• Overview of UNIX programming environment
• Fundamental Concepts
• Programming Conventions

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Overview

• Kernel operating system core. It controls the
  computers resources.
• Drivers Control peripheral devices
• Library routines provides enhanced versions of
  system calls, or facilities not found in system
  calls
• Shell command interpreter for users

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Fundamental Concepts

• Files provide storage for data and access to
  devices and special services.
• file type defines service and usage
• file has filename and namespace
• Processes provide the framework in which
  programs execute.
• process consists of state info., scheduling
  handle, stack, and text and data

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Conventions

• Programming interface
• main(int argc, char argv)
• File descriptors
• 0standard input, 1standard output, 2 standard
  error
• Exit values
• 0success,non-zero errors
• Header files
• by default /usr/include

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Readings

• Rago, UNIX System V Network Programming,
• Chapter 1
• Chapter 2 2.1-2.3