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Title: Understanding Operating Systems Sixth Edition


1
Understanding Operating Systems Sixth Edition
  • Chapter 15Windows Operating Systems

2
Learning Objectives
  • After completing this chapter, you should be
    able to describe
  • The design goals for Windows operating systems
  • The role of MS-DOS in early Windows releases
  • The role of the Memory Manager and Virtual Memory
    Manager
  • The use of the Device, Processor, and Network
    Managers
  • System security challenges
  • The Windows user interface

3
Windows Development
  • First Windows product communication method
  • Graphical user interface (GUI)
  • Primary user communication method
  • Needed underlying operating system to translate
    users requests into system commands
  • Windows 1.0 (1985)
  • First Windows application
  • Ran on PC-compatible microcomputers
  • Not a true operating system
  • Ran on top of MS-DOS
  • Interface between MS-DOS and user

4
Early Windows Products
  • Advancements in Windows
  • Increasingly sophisticated GUI design
  • Increasingly powerful desktop computers
  • Windows 3.1
  • Standardized look and feel
  • Similar to Apples Macintosh computer
  • Entry level product
  • Single-user installations or small-business
    environments

5
Early Windows Products (cont'd.)
  • Windows for Workgroups
  • Accommodate network users needs (small business)
  • Programs and features for small LANs
  • Share directories, disks, printers
  • Personal intercommunication e-mail, chat programs

6
Operating Systems for Home and Professional Users
  • Disadvantages running Windows on MS-DOS
  • Little built-in security
  • No multitasking
  • No interprocess communication capability
  • Difficulty moving MS-DOS to other platforms
  • MS-DOS worked closely with hardware
  • Microsoft response
  • Developed and released succession of Windows
  • Not mere GUIs had home and office user appeal
  • Development of powerful networking products
  • Windows NT (New Technology)

7
Operating Systems for Home and Professional Users
(cont'd.)
8
Operating Systems for Networks
  • Windows NT Development (1993)
  • No reliance on MS-DOS support
  • Primary market requirements
  • Portability
  • Multiprocessing capabilities
  • Distributed computing support
  • Government procurement compliance requirements
  • Government security certification

9
Operating Systems for Networks (cont'd.)
10
Operating Systems for Networks (cont'd.)
  • Windows NT versions
  • Windows NT Workstation
  • Individuals
  • Desktop operating system
  • Windows NT Server
  • Small to medium-sized offices
  • Web servers and off-site locations
  • Windows NT Server Enterprise Edition
  • Larger and more complex networks

11
Operating Systems for Networks (cont'd.)
  • Windows NT name changed (1999)
  • Windows 2000 four packages
  • Windows 2000 Professional
  • Windows 2000 Server
  • Windows 2000 Advanced Server
  • Windows 2000 Datacenter Server
  • Windows Server 2003
  • Same four packages plus Web edition
  • Windows Server 2008 Release 2 (2009)

12
Design Goals
  • Fulfilling marketing requirements
  • Incorporate security features
  • Facilitate decision making (coding process)
  • Windows networking operating systems
  • Influenced by several operating system models
  • Use already-existing frameworks
  • Introduced new features
  • Object model
  • Manage and allocate resources
  • Symmetric multiprocessing (SMP)
  • Maximum multiprocessor performance

13
Design Goals (cont'd.)
  • Needs
  • Accommodate user needs
  • Optimize resources
  • Response
  • Five design goals
  • Extensibility
  • Portability
  • Reliability
  • Compatibility
  • Performance

14
Extensibility
  • Easily enhancing operating system
  • Ensuring code integrity separate functions
  • Privileged executive process
  • Kernel mode
  • Processors mode of operation
  • All machine instructions allowed
  • System memory accessible
  • Nonprivileged processes protected subsystems
  • User mode
  • Certain instructions not allowed
  • System memory not accessible

15
Extensibility (cont'd.)
  • Four more features
  • Modular structure
  • New components added to executive process
  • Objects
  • Abstract data types manipulated by special
    services
  • System resources managed uniformly
  • Drivers
  • New file systems, devices, and networks added to
    system at any time
  • Remote procedure call
  • Application calls remote services
  • Regardless of location on network

16
Portability
  • Operate on different machines
  • Different processors or configurations
  • Minimum amount of recoding
  • System guidelines to achieve goal
  • Written in a standardized, high-level language
  • Available in all machines
  • Accommodated ported hardware
  • Minimized direct code interaction with hardware
  • Reduced incompatibility errors
  • Hardware-dependent code isolated into modules
  • Easily modifiable when ported

17
Portability (cont'd.)
  • Windows NT and successors features
  • Modular code
  • Written in C (most of code)
  • Hardware abstraction layer (HAL)
  • Dynamic-link library
  • Provides isolation from vendors hardware
    dependencies

18
Reliability
  • Robustness of system
  • Ability to protect itself and users
  • Accidental or deliberate user programs damage
  • Features strengthening system
  • Structured exception handling
  • Modular design
  • NTFS file system (NT file system)
  • Can recover from all error types
  • Advanced security architecture
  • Virtual memory strategy

19
Compatibility
  • Execute programs written for other operating
    systems (or earlier system versions)
  • Use protected subsystems
  • Provide application execution different from
    primary programming interface
  • Provides source-level POSIX application
    compatibility
  • Recent Windows versions
  • Support existing file systems
  • FAT, CDFS, NTFS
  • Built-in verification
  • Important hardware and software

20
Performance
  • Achieve good performance levels
  • Windows features
  • Testing and optimization system calls, page
    faults, crucial processes
  • Incorporate local procedure call (LPC) guarantee
    fast communication among protected subsystems
  • Maximize speed of frequently used system services
  • Critical Windows networking software elements
    built into operating system privileged portion

21
IQ TEST 1
  • 1. Which of the following Microsoft Windows
    networking operating systems includes a Web
    edition?
  • A. Window NT 4.0
  • B. Windows 2000
  • C. Windows Server 2003
  • D. All of the above
  • Answer C
  •  
  • 2. Which of the following is a design goal of the
    Windows operating systems? (Choose all that
    apply.)
  • A. Extensibility
  • B. Profitability
  • C. Compatibility
  • D. Performance
  • Answer A, C, and D
  • 3. Which of the following file systems is
    supported by recent versions of Windows operating
    systems? (Choose all that apply.)
  • A. POSIX
  • B. CDFS
  • C. NTSC
  • D. NTFS

22
Memory Management
  • Every operating system
  • Has own physical memory view
  • Makes application programs access memory in
    specified ways
  • Full physical memory
  • Virtual Memory Manager pages some memory contents
    to disk
  • Challenge for all Windows operating systems
  • Run application programs (Windows, POSIX)
  • Without programs crashing into each others memory

23
Memory Management (cont'd.)
  • Memory layout (recent Windows versions)
  • Operating system high virtual memory
  • User code and data low virtual memory
  • User process
  • Cannot read or write system memory directly
  • Memory paged to disk
  • User-accessible memory
  • System memory segment labeled paged pool
  • Memory never paged to disk
  • System memory segment labeled nonpaged pool

24
Memory Management (cont'd.)
25
User-Mode Features
  • VM Manager (virtual machine manager)
  • User-mode subsystems share memory efficiently
  • Provides process services to manage virtual
    memory
  • Allocate memory in two stages
  • Read and/or write protection for virtual memory
  • Lock virtual pages in physical memory
  • Retrieve information about virtual pages
  • Protect virtual pages
  • Rewrite virtual pages to disk

26
Virtual Memory Implementation
  • VM manager reliance
  • Address space management
  • Paging techniques
  • Address space management
  • Upper half of virtual address space
  • Accessible only to kernel-mode processes
  • Code in lower part (kernel code and data)
  • Never paged out of memory

27
Virtual Memory Implementation (cont'd.)
  • Paging (VM manager is pager)
  • Transfers pages
  • Between memory page frames and disk storage
  • Complex combination
  • Software policies when to bring a page into
    memory and where to put it
  • Hardware mechanisms exact manner VM Manager
    translates virtual addresses into physical
    addresses
  • Pager not portable
  • Windows small code and well isolated

28
Virtual Memory Implementation (cont'd.)
  • Paging policies
  • Dictate how and when paging done
  • Composition
  • Fetch policy determines when pager copies a page
    from disk to memory
  • Placement policy determines where virtual page
    is loaded in memory
  • Replacement policy determines which virtual page
    is removed from memory to make room for a new
    page

29
Processor Management
  • Windows
  • Preemptive-multitasking, multithreaded operating
    system
  • Windows NT process
  • Requires at least one thread
  • Default
  • Process contains one thread

30
Processor Management (cont'd.)
  • Thread composition
  • A unique identifier
  • Contents of volatile set of registers indicating
    processors state
  • Two stacks used during threads execution
  • Private storage area used by subsystems and
    dynamic-link libraries

31
Processor Management (cont'd.)
  • Threads
  • Thread components called threads context
  • Actual data forming context varies from one
    processor to another
  • Kernel
  • Schedules threads for execution on a processor
  • Thread actually executes code
  • Overhead incurred by thread is minimal
  • Unitasking
  • Process with single thread

32
Processor Management (cont'd.)
33
Processor Management (cont'd.)
  • Multithreading using multitasking
  • Systems with multiple processors
  • Process has as many threads as CPUs available
  • All threads belonging to one process share
    global variables, heap, environment strings
  • Versions of Windows since NT
  • Include some synchronization mechanisms
  • Avoid problems with multiple threads

34
Processor Management (cont'd.)
35
Device Management
  • Windows NT I/O system and networking descendents
    provide
  • Multiple installable file systems (FAT, CDFS,
    NTFS)
  • Services making device-driver development easy
  • Workable on multiprocessor systems
  • Adding drivers to the system (system
    administrators)
  • Remove them dynamically
  • Fast I/O processing
  • Drivers written in high-level language
  • Mapped file I/O capabilities
  • Image activation, file caching, application use

36
Device Management (cont'd.)
  • I/O system
  • Packet driven
  • I/O request represented by I/O request packet
    (IRP)
  • IRP
  • Data structure controlling how I/O operation
    processed at each step
  • I/O manager IRP creation
  • Creates an IRP representing each I/O operation
  • Passes IRP to appropriate driver
  • Disposes of packet when operation complete

37
Device Management (cont'd.)
  • Driver IRP receipt
  • Performs specified operation
  • Passes it back to I/O manager or
  • Passes it through I/O manager to another driver
    for further processing

38
Device Management (cont'd.)
  • I/O manager tasks
  • Supplies code, common to different drivers
  • Manages buffers for I/O requests
  • Provides time-out support for drivers
  • Records installable file systems loaded into
    operating system
  • Provides flexible I/O facilities
  • Subsystems (POSIX) implement their respective I/O
    application programming interfaces
  • Allows dynamic loading of device drivers and file
    systems
  • Based on users needs

39
Device Management (cont'd.)
  • Windows I/O services
  • Device-independent model
  • Multilayered device driver concept
  • Device driver made up of standard set of routines
  • Initialization routine, dispatch routine, start
    I/O routine, completion routine, unload routine,
    error logging routine

40
Device Management (cont'd.)
  • I/O manager
  • Determine driver called to process request
  • Using file objects name
  • Driver object
  • Represents individual driver in system
  • I/O manager creates
  • Created when driver loaded into system
  • May have multiple device objects connected to it
  • Device object
  • Physical, logical, or virtual device on the
    system
  • Describes device characteristics

41
Device Management (cont'd.)
42
Device Management (cont'd.)
43
Device Management (cont'd.)
  • Device objects list
  • Represents physical, logical, virtual devices
  • Controlled by the driver
  • Advantages of using different objects
  • Portability
  • Frees I/O manager from knowing details about
    drivers
  • Follows pointer to locate driver
  • Easy loading of new drivers
  • Easy assigning drivers to control additional or
    different devices
  • If system configuration changes

44
Device Management (cont'd.)
45
Device Management (cont'd.)
  • I/O manager knows nothing about file system
  • Overhead
  • I/O manager passes information requests back and
    forth
  • Uses single-layer device driver approach
  • Simple devices (serial and parallel printer
    ports)
  • Uses multilayered approach
  • More complicated devices (hard drives)
  • I/O operations asynchronous
  • Almost all low-level operations

46
File Management
  • Windows current versions
  • Designed to be independent of file system on
    which they operate
  • Support multiple file systems for hard disks
    including
  • MS-DOSs FAT file system
  • 32-bit FAT file system
  • NTFS

47
File Management (cont'd.)
  • Virtual file
  • Primary file handling concept (current windows)
  • Programs perform I/O on virtual files
  • File handles manipulate them
  • Executive file object representing all sources
    and destinations of I/O
  • Processes call native file object services to
    read from or write to file
  • I/O manager directs virtual file requests
  • Real files, file directories, physical devices

48
File Management (cont'd.)
  • File objects
  • Hierarchical names
  • Protected by object-based security
  • Support synchronization
  • Handled by object services
  • Opening file
  • Process supplies files name and type of access
    required

49
File Management (cont'd.)
  • File objects bridge gap
  • Between physical devices characteristics and
    directory structures, file system structures,
    data formats
  • Provides memory-based representation of shareable
    physical resources
  • Created with new set of handle-specific
    attributes
  • Each time process opens a handle

50
File Management (cont'd.)
51
File Management (cont'd.)
52
File Management (cont'd.)
  • Mapped file I/O
  • Important feature of I/O system
  • Achieved by cooperation with I/O system and VM
    Manager
  • Memory-mapped files exploit VM capabilities
  • Cache manager uses mapped I/O
  • Manages its memory-based cache
  • File management system supports long filenames
  • Include spaces and special characters
  • Automatically shortens filenames when required

53
Network Management
  • Networking
  • Integral to Windows NT-based operating systems
  • Provides services
  • User accounts, resource security
  • Communication between computers
  • Named pipes
  • Provide high-level interface for passing data
    between two processes (regardless of locations)
  • Mailslots
  • Provide one-to-many and many-to-one communication
    mechanisms

54
Network Management (contd.)
  • Microsoft Networks (MS-NET)
  • Released in 1984
  • Model for NT Network Manager
  • Three components
  • Redirector
  • Server message block (SMB) protocol
  • Network server
  • MS-NET components
  • Extensively refurbished and incorporated into
    Windows NT and later versions

55
Network Management (cont'd.)
  • Redirector
  • Coded in C programming language
  • Implemented as loadable file system driver
  • Not dependent on systems hardware architecture
  • Function
  • Direct I/O request from user or application to
    remote server that has appropriate file or
    resource
  • Network can incorporate multiple redirectors

56
Network Management (cont'd.)
  • SMB Protocol
  • High-level specification
  • Formatting messages sent across network
  • OSI model correlation
  • Application layer (layer 7)
  • Presentation layer (layer 6)
  • API called NETBIOS interface
  • Used to pass I/O requests structured in SMB
    format to remote computer
  • SMB protocols and NETBIOS API
  • Adopted in several networking products before
    appearing in Windows

57
Network Management (cont'd.)
  • Windows Server operating systems
  • Written in C
  • Complete compatibility with existing MS-NET and
    LAN manager SMB protocols
  • Implemented as loadable file system drivers
  • No dependency on hardware architecture
  • Where operating system running

58
Directory Services
  • Active Directory
  • Database storing all information types
  • General-purpose directory service for
    heterogeneous network
  • Built entirely around DNS and LDAP
  • Groups machines into administrative units called
    domains
  • Each domain gets a DNS domain name (e.g.,
    pitt.edu)
  • Each domain must have at least one domain
    controller
  • Domain can have more than one domain controller
  • Active Directory clients use standard DNS and
    LDAP protocols to locate objects on the network

59
Directory Services (cont'd.)
60
Security Management
  • Windows network operating systems
  • Provide object-based security model
  • Security object
  • Represent any resource in system (file, device,
    process, program, or user)
  • Allows administrators to give precise security
    access
  • To specific objects in system allowing them to
    monitor and record how objects used
  • Windows biggest concern
  • Aggressive patch management needed
  • Combat many viruses and worms

61
Security Basics
  • U.S. Department of Defense
  • Identified and categorized operating system
    features
  • Seven levels of security
  • Compliance with Class C2 level security
  • Features in Windows
  • A secure logon facility
  • Discretionary access control
  • Auditing ability
  • Memory protection

62
Security Basics (cont'd.)
  • Multilayered security system
  • Strives to prevent access by unauthorized users
  • Password management first security layer
  • NTFS second security layer
  • File access security
  • Distinguishes between owners and groups
  • Users decide operation types person is allowed to
    perform on a file
  • Gives user auditing capabilities
  • Automatically keeps track of who uses files and
    how

63
Security Terminology
  • Built-in security
  • Necessary element for managers of Web servers and
    networks
  • Requires authentication mechanism allowing client
    to prove identity to server
  • Client supplies authorization information
  • Server uses information to determine specific
    access rights given to client
  • Provides data integrity using various methods
  • Windows uses Kerberos security

64
Security Terminology (cont'd.)
  • Kerberos Security
  • Authentication, data integrity, data privacy,
    mutual authentication
  • Each domain has own Kerberos server
  • Microsoft implemented standard Kerberos protocol
  • Microsoft separated users of distributed security
    services from their providers
  • Allows support for many options without unusable
    complexity

65
Security Terminology (cont'd.)
66
User Interface
  • Start an application
  • Double-click application icon
  • Select it from Start menu
  • Quit application
  • Select Exit from File menu
  • Click x in top-right corner of window

67
User Interface (cont'd.)
  • Start Menu
  • Divides functions into logical groups
  • Users access common functions
  • All Programs
  • Documents, Pictures, Music, and Computer
  • Control Panel
  • Help and Support
  • Search

68
User Interface (cont'd.)
69
User Interface (cont'd.)
  • Windows Task Manager
  • Open
  • Pressing and holding the CTRL, ALT, delete keys
  • User view running applications and processes
  • Set priorities of each
  • User views information
  • Performance, networking, users logged into system
  • Windows Explorer (standard utility program)
  • Contains director, file display tools,
    file-finding tool
  • Series of pull-down menus
  • File, Edit, View, Tools, Help, etc.

70
User Interface (cont'd.)
71
User Interface (cont'd.)
72
User Interface (cont'd.)
  • Networked systems
  • Identify and access network resources
  • Folders, printers, connections to other nodes
  • Command interface
  • Resembles MS-DOS
  • Available from most Windows desktops
  • Keyboard shortcuts (CTRLC for copy)
  • Built-in input methods and fonts for languages
  • Windows offers an on-screen keyboard
  • Resource monitor

73
User Interface (cont'd.)
74
User Interface (cont'd.)
75
User Interface (cont'd.)
76
User Interface (cont'd.)
77
User Interface (cont'd.)
78
IQ TEST 2
1. The VM Manager uses a(n) ____________________
replacement policy. A. LRU B. MRU C. FCFS D.
FIFO Answer D   2. A(n) ____________________ is
a data structure that controls how the I/O
operation is processed at each step. Answer I/O
request packet (IRP)   3. The segment of system
memory labeled ____________________ is never
paged to disk because its used to store critical
NT objects. Answer nonpaged pool
79
Summary
  • Current Windows operating systems
  • Ease-of-use with technical power
  • Operate network across several platforms
  • Significant security controls
  • Allowed inroads to organizations requiring
    consistent protection
  • Authentication models support new user interfaces
  • Implementation of different security
    architectures
  • Require aggressive patch management
  • Target of viruses and worms
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