Slide 1:70-270: MCSE Guide to Microsoft Windows XP Professional Second Edition, EnhancedChapter 11: Windows XP Professional Application Support

Slide 2:Objectives

Understand the Windows XP Professional system architecture Deploy Win32 applications Fine-tune the application environment for DOS and the virtual DOS machine Fine-tune the application environment for Win16 Work with Windows application management facilities

Slide 3:Windows XP Professional System Architecture

Components: Environment subsystem Executive Services Subsystem: Operating environment Emulates another operating system Kernel mode components Permitted to access system objects and resources directly

Slide 4:Kernel Mode vs. User Mode

Main difference: Memory usage User mode: Each process perceives entire 4 GB of virtual memory as its exclusive property Upper 2 GB reserved for operating system use Address space entirely virtual Processes may share memory areas with other processes

Slide 5:Kernel Mode Versus User Mode (continued)

User mode: One user mode process cannot crash another Processes cannot access hardware or communicate with other processes directly Kernel mode: May access all hardware and memory in computer All operations share the same memory space One kernel mode function can corrupt another’s data Can cause the operating system to crash

Slide 6:Processes and Threads

Process: Defines operating environment in which application or any major operating system component runs Includes: Own private memory space Set of security descriptors Priority level for execution Processor-affinity data List of threads

Slide 7:Processes and Threads (continued)

Thread: Basic executable unit in Windows XP Every process includes at least one thread Consists of: Placeholder information associated with single use of any program that can handle multiple concurrent users or activities Associated with processes Do not exist independently

Slide 8:Processes and Threads (continued)

Applications must be explicitly designed to take advantage of threading Processes can create other processes Called child processes Child processes can inherit some of the characteristics and parameters of their parent process

Slide 9:Processes and Threads (continued)

Context Current collection of Registry values and runtime environment variables in which a process or thread runs

Slide 10:Environment Subsystems

Windows XP Professional Offers support for various application platforms Includes limited support and backward compatibility for: 16-bit Windows applications DOS applications. Known as environment subsystems

Slide 11:Environment Subsystems (continued)

Benefits of Environment subsystems: Permits users to run more than one type of application concurrently Makes maintaining the operating system easier Easy to add to or enhance Windows XP Each subsystem runs as separate user-mode process Except for Win32 subsystem

Slide 12:Environment Subsystems (continued)

Local procedure call (LPC) Dynamic link library (DLL) Context switch: All the information for the calling process must be unloaded and replaced with the information for the called process

Slide 13:The Win32 Subsystem

Only subsystem required for the functioning of the operating system Handles all major interface capabilities Foundation upon which virtual DOS machines (VDMs) rest

Slide 14:Win32 Applications

Applications run under that operating system

Slide 15:The Environment Subsystem

Win32 subsystem: Main environment subsystem under Windows XP Only one required for operation

Slide 16:Multithreading

Multithreaded process: Contains more than one thread of execution Multithreading advantages: Provides multiple threads of execution within single memory space Does not require that messages be passed between processes Threads don’t require as much context information as processes

Slide 17:Memory Space

Synchronization objects Critical section: Section of code that modifies data structures used by several threads

Slide 18:Input Message Queues

Organize user input Takes user messages from general input queue Distributes them to input message queue

Slide 19:Base Priorities

Priority class: Helps determine the priority at which threads in process must run Scale from 0 (lowest) to 31 (highest) Each thread may have its own priority Always relative to priority assigned to underlying process Known as base priority

Slide 20:DOS and the Virtual DOS Machine

DOS and Win16 applications Run within a virtual DOS machine (VDM) VDM: Special environment process that simulates DOS environment DOS operating environment Supports straightforward DOS emulation Win16 operating environment Supports operation of Win16 applications

Slide 21:DOS and the Virtual DOS Machine

Occurs within a Win32 process named ntvdm.exe

Slide 22:VDM Components

Ntio.sys Ntdos.sys Ntvdm.exe Ntvdm.dll Redir.exe

Slide 23:Virtual Device Drivers

Underlies DOS applications Communicate with Windows XP 32-bit drivers Windows XP supplies VDDs for: Mouse Keyboard Printers Communication ports File system

Slide 24:AUTOEXEC.BAT and CONFIG.SYS

AUTOEXEC.NT Replaces AUTOEXEC.BAT CONFIG.NT Replaces CONFIG.SYS

Slide 25:AUTOEXEC.NT

Slide 26:CONFIG.NT

Slide 27:Custom DOS Environments

Use Properties dialog box to customize Tabs: General Program Font Memory Screen Misc Compatibility Security Summary

Slide 28:Custom DOS Environments (continued)

Slide 29:Win16 Concepts and Applications

Run in a VDM All Win16 applications run in the same VDM by default Can run in separate VDMs Win16-on-Win32 (WOW)VDM: Runs as a multithreaded application Each Win16 application occupies a single thread

Slide 30:Win16 Concepts and Applications (continued)

Slide 31:Win16-on-Win32 Components

Wowexec.exe Wow32.dll Mmtask.tsk Ntvdm.exe ntvdm.dll ntio.sys

Slide 32:Win16-on-Win32 Components (continued)

redir.exe Vdmredir.dll Krnl386.exe Gdi.exe User.exe Calls made to 16-bit drivers Transferred (“thunked”) to appropriate 32-bit driver without the application having to call driver directly

Slide 33:Win16-on-Win32 Components (continued)

XP sustains WOW environment until System is restarted Manually terminate the Wowexec.exe task

Slide 34:Memory Space

Multiple threads running in single process can affect the performance of each application Can make tracking applications more difficult If one of application goes astray and causes the VDM to freeze or crash, all applications in that VDM will be affected

Slide 35:Separate and Shared Memory

Separate VDMs advantages: Increase reliability of applications as a whole One errant application won’t take down all the other Win16 applications if it crashes Preemptive multitasking is possible

Slide 36:Separate and Shared Memory (continued)

Disadvantages: Requires 2 MB of space in the paging file and 1 MB of additional working set size Increased time to switch from one application to another To choose: Try both ways and compare performance

Slide 37:Message Queues

Win16 applications running in a single process share message queue If one application becomes unable to accept input Blocks all other Win16 applications in VDM from accepting further input

Slide 38:Threads

Win16 threads that run in a VDM do not multitask like threads running in the Win32 subsystem Cooperatively multitasked Any one thread can hog CPU

Slide 39:Using Only Well-behaved DOS and Win16 Applications

“Ill behaved” Access system hardware directly Bypass any access APIs or drivers Do not run in a VDM “Well behaved” Uses standard DOS or Windows 3.x APIs

Slide 40:Other Windows Application Management Facilities

Additional methods for managing or accessing applications Program Compatibility Wizard Publish applications using Group Policy Objects Resolve problems related to programs that use different versions of DLLs with same name

Slide 41:Program Compatibility Wizard

Support the installation of older Windows applications

Slide 42:Program Compatibility Wizard (continued)

Slide 43:Assigning and Publishing Applications on Windows XP Professional

Use group policies Assign or publish programs to users or computers In: Domain Site Organizational unit

Slide 44:Assigning and Publishing Applications on Windows XP Professional (continued)

Assign Windows Installer package to some group or user Windows Installer package: Complete set of software installation and configuration instructions .msi file Use Active Directory Users and Computers MMC snap-in

Slide 45:Resolving DLL Conflicts in Windows XP

Windows Side by Side (WinSxS) isolation support New feature Checks DLLs and other common code components before installing them on computer Finds potential conflicts Automatically makes Registry modifications necessary to point to alternate versions of DLLs

Slide 46:Summary

Main parts: Environment subsystems Executive Services User applications Win32 subsystem Crucial to the functioning of Windows XP VDM Support DOS and Win16 programs

Slide 47:Summary (continued)

Program Compatibility Wizard Group Policy Objects to assign and publish Windows applications Recognize and resolve potential conflicts with DLLs