Chapter Eleven Windows XP Professional Application Support

Chapter ElevenChapter Eleven

Windows XP Windows XP Professional Professional Application Application

SupportSupport

ObjectivesObjectives Understand the runtime environments and Understand the runtime environments and

applications support in Windows XP applications support in Windows XP ProfessionalProfessional

Deploy DOS, Win16, and Win32 applicationsDeploy DOS, Win16, and Win32 applications Fine-tune the application environment for Fine-tune the application environment for

DOS and Win16 executablesDOS and Win16 executables Understand how to assign and publish Understand how to assign and publish

applications using Group Policyapplications using Group Policy Address application compatibility issuesAddress application compatibility issues

Windows XP Professional Windows XP Professional System ArchitectureSystem Architecture

Fundamentally, the Windows XP Fundamentally, the Windows XP Professional operating system Professional operating system incorporates three primary incorporates three primary components:components: Environment subsystemsEnvironment subsystems Executive ServicesExecutive Services User applicationsUser applications


Environment Environment subsystemssubsystems offer runtime offer runtime support for a variety of different kinds of support for a variety of different kinds of applicationsapplications

Executive Services and the underlying Executive Services and the underlying Windows XP Windows XP kernelkernel define the define the kernel modekernel mode for this operating system and its runtime for this operating system and its runtime environmentenvironment

User applications provide the functionality and User applications provide the functionality and capabilities that rank Windows XP Professional capabilities that rank Windows XP Professional among the most powerful network operating among the most powerful network operating systems in use todaysystems in use today


Figure 11-1: Components of the Windows XP Professional architecture

Kernel Mode Versus User Kernel Mode Versus User ModeMode

The main difference between kernel mode The main difference between kernel mode and and user modeuser mode lies in how memory is lies in how memory is used by kernel-mode components and used by kernel-mode components and user-mode componentsuser-mode components

Processes running in user mode cannot Processes running in user mode cannot access hardware or communicate with access hardware or communicate with other processes directlyother processes directly

When code runs in the Windows XP kernel When code runs in the Windows XP kernel mode, it may access all hardware and mode, it may access all hardware and memory in the computermemory in the computer

Processes and ThreadsProcesses and Threads ProcessProcess

An environment in which the executable An environment in which the executable portion of a program runs, defining its portion of a program runs, defining its memory usage, which processor to use, memory usage, which processor to use, its object, and so forthits object, and so forth

ThreadThread Executable portion of a program, with a Executable portion of a program, with a

priority based on the priority of its priority based on the priority of its processprocess

Processes and ThreadsProcesses and Threads

Figure 11-2: The Process tab in Task

Manager displays all currently active Windows XP

Professional processes

Processes and ThreadsProcesses and Threads

Child processesChild processes Inherits operating characteristics from its Inherits operating characteristics from its

parent subsystemparent subsystem Parent processParent process

Windows XP environment subsystem that Windows XP environment subsystem that creates a runtime processcreates a runtime process

ContextContext Current collection of Registry values and Current collection of Registry values and

runtime environment variables in which runtime environment variables in which process or thread runsprocess or thread runs

Environment SubsystemsEnvironment Subsystems Windows XP Professional’s support for Windows XP Professional’s support for

multiple runtime environments, also multiple runtime environments, also known as environment subsystems, known as environment subsystems, confers numerous advantagesconfers numerous advantages

Local procedure call (LPC)Local procedure call (LPC) Technique to permit processes to Technique to permit processes to

exchange data in the Windows XP exchange data in the Windows XP runtime environmentruntime environment

Dynamic link library (DLL)Dynamic link library (DLL) Collection of virtual procedure callsCollection of virtual procedure calls

Environment SubsystemsEnvironment Subsystems Context switchContext switch

Act of unloading the context Act of unloading the context information for one process and information for one process and replacing it with the information for replacing it with the information for anotheranother

To permit the operating system to To permit the operating system to run more efficiently, Windows XP run more efficiently, Windows XP avoids making context switches avoids making context switches whenever possiblewhenever possible

The Win32 SubsystemThe Win32 Subsystem Win32 subsystemWin32 subsystem

Operating environment that supports Operating environment that supports 32-bit Windows applications32-bit Windows applications

Is required to run Windows XPIs required to run Windows XP Also the foundation upon which Also the foundation upon which virtual virtual

DOS machines (VDMs)DOS machines (VDMs) rest rest

Win32 ApplicationsWin32 Applications Environment subsystemEnvironment subsystem

The Win32 subsystem is the main The Win32 subsystem is the main environment subsystem under Windows environment subsystem under Windows XP, and the only one required for XP, and the only one required for operationoperation

MultithreadingMultithreading When a program’s process contains When a program’s process contains

more than one thread, it is said to be a more than one thread, it is said to be a multithreaded processesmultithreaded processes

Win32 ApplicationsWin32 Applications

Memory spaceMemory space Section of code that modifies data Section of code that modifies data

structures used by several threads is structures used by several threads is called a called a critical sectioncritical section

It is very important that a critical section It is very important that a critical section never be overwritten by more than one never be overwritten by more than one thread at oncethread at once

Application use Windows XP Application use Windows XP synchronization objectssynchronization objects to prevent this to prevent this from happeningfrom happening

Win32 ApplicationsWin32 Applications Input message queuesInput message queues

Queue for each process that contains Queue for each process that contains the messages sent to the process from the messages sent to the process from the userthe user

Base prioritiesBase priorities Lowest priority that a thread may be Lowest priority that a thread may be

assignedassigned

Win32 ApplicationsWin32 Applications

Figure 11-3: The Task

Manager’s Process tab with priority

options on display

DOS and the Virtual DOS DOS and the Virtual DOS MachineMachine

It is reasonable to describe two It is reasonable to describe two separate operating environments that separate operating environments that can run within a VDM:can run within a VDM: One supports straightforward DOS One supports straightforward DOS

emulation and may be called the emulation and may be called the DOS DOS operating environmentoperating environment

The other supports operation of Win16 The other supports operation of Win16 applications within a VDM, and may be applications within a VDM, and may be called the Win16 operating environmentcalled the Win16 operating environment

DOS and the Virtual DOS DOS and the Virtual DOS MachineMachine

Figure 11-4: The Task Manager’s Process tab shows ntvdm.exe running when a 16-bit DOS

application is loaded

VDM ComponentsVDM Components The VDM runs using the following The VDM runs using the following

files:files: Ntio.sysNtio.sys Ntdos.sysNtdos.sys Ntvdm.exeNtvdm.exe Ntvdm.dllNtvdm.dll Redir.exeRedir.exe

Virtual Device Drivers Virtual Device Drivers (VDDs)(VDDs)

DOS applications do not DOS applications do not communicate directly with Windows communicate directly with Windows XP driversXP drivers Instead, a layer of Instead, a layer of VDDsVDDs underlies underlies

these applications, and they these applications, and they communicate with Windows XP 32-bit communicate with Windows XP 32-bit driversdrivers VDDs are device drivers used by VDMsVDDs are device drivers used by VDMs

AUTOEXEC.BAT and AUTOEXEC.BAT and CONFIG.SYSCONFIG.SYS

Figure 11-5: AUTOEXEC.NT as it appears in Notepad


Figure 11-6: CONFIG.NT as it appears in Notepad


Figure 11-7: The Registry Editor shows the variables defined within the …\Environment subkey

Custom DOS Custom DOS EnvironmentsEnvironments

Figure 11-8: MASTERMIND.EXE

Properties, Programs tab

Custom DOS Custom DOS EnvironmentsEnvironments

Figure 11-9: MASTERMIND.EXE

Properties Misc tab

Win16 Concepts and Win16 Concepts and ApplicationsApplications

Like DOS applications, Win16 Like DOS applications, Win16 applications also run in a VDMapplications also run in a VDM

Unlike DOS applications, all Win16 Unlike DOS applications, all Win16 applications run in same VDM unless applications run in same VDM unless you specify otherwiseyou specify otherwise This lets them act like Win32 applicationsThis lets them act like Win32 applications This also lets multiple Win16 applications This also lets multiple Win16 applications

interact with one another within a single interact with one another within a single VDMVDM


MultitaskingMultitasking Sharing processor time between Sharing processor time between

threadsthreads Win16-on-Win32 (WOW)Win16-on-Win32 (WOW)

Name for collection of components, Name for collection of components, interfaces, and capabilities that permits interfaces, and capabilities that permits Win32 subsystems to provide native Win32 subsystems to provide native support for well-behaved 16-bit support for well-behaved 16-bit Windows applicationsWindows applications


Figure 11-10: The Task Manager

Processes tab showing the wowexec environment

Win16-on-Win32 Win16-on-Win32 ComponentsComponents

Wowexec.exeWowexec.exe Wow32.dllWow32.dll Mmtask.tskMmtask.tsk Ntvdm.exe, ntvdm.dll, ntio.sys, and Ntvdm.exe, ntvdm.dll, ntio.sys, and

redir.exeredir.exe

Win16-on-Win32 Win16-on-Win32 ComponentsComponents

Vdmredir.dllVdmredir.dll Krnl386.exeKrnl386.exe Gdi.exeGdi.exe User.exeUser.exe

Memory SpaceMemory Space Separate and shared memorySeparate and shared memory

The “lose one, lose them all” effect of a single The “lose one, lose them all” effect of a single shared VDM explains why you might choose shared VDM explains why you might choose to run Win16 applications in separate VDMsto run Win16 applications in separate VDMs

Disadvantages of running Win16 applications Disadvantages of running Win16 applications in separate memory spaces hinge on memory in separate memory spaces hinge on memory usage and interprocess communicationsusage and interprocess communications

Message queuesMessage queues All Win16 applications running in a single All Win16 applications running in a single

process share a message queueprocess share a message queue

Memory SpaceMemory Space ThreadsThreads

All application threads within a WOW All application threads within a WOW VDM are cooperatively multitaskedVDM are cooperatively multitasked

Using only well-behaved DOS and Using only well-behaved DOS and Win16 applicationsWin16 applications In Windows XP terminology, any In Windows XP terminology, any

application that attempts direct access application that attempts direct access to hardware is called “ill-behaved”to hardware is called “ill-behaved” Such applications will not run in a VDMSuch applications will not run in a VDM

Program Compatibility Program Compatibility WizardWizard

Figure 11-11: The Program Compatibility Wizard starts with a welcome screen, then guides you through automated compatibility checks


Figure 11-12: Compatibility mode settings are selected from a specific list of available options


Figure 11-13: The Compatibility tab in the Properties window for

any executable file provides direct access to the same controls offered

through the Program Compatibility Wizard

Assigning and Publishing Assigning and Publishing Applications on Windows Applications on Windows

XP ProfessionalXP Professional PackagePackage File that contains instructions for the File that contains instructions for the

Windows InstallerWindows Installer TransformTransform

Specific type of Microsoft Installer file Specific type of Microsoft Installer file that usually ends in .mstthat usually ends in .mst

Resolving DLL Conflicts Resolving DLL Conflicts in Windows XPin Windows XP

Windows XP includes a remarkable new Windows XP includes a remarkable new technology called Windows Side by Side technology called Windows Side by Side (WinSxS) isolation support(WinSxS) isolation support

By default, Windows checks DLLs and By default, Windows checks DLLs and other common code components before other common code components before installing them on a computerinstalling them on a computer If it finds potential conflicts, it automatically If it finds potential conflicts, it automatically

makes the Registry modifications necessary to makes the Registry modifications necessary to point to alternate versions of DLLs and other point to alternate versions of DLLs and other shared objects in a special directory named shared objects in a special directory named %systemroot%\WINDOWS\WinSxS%systemroot%\WINDOWS\WinSxS

Chapter SummaryChapter Summary Windows XP Professional is divided into three Windows XP Professional is divided into three

main parts:main parts: Environment subsystemsEnvironment subsystems Executive ServicesExecutive Services User applicationsUser applications

In addition to the basic Win32 Subsystem, In addition to the basic Win32 Subsystem, two special-purpose operating environments two special-purpose operating environments (VDM and WOW) also run within that (VDM and WOW) also run within that subsystem to provide backward compatibility subsystem to provide backward compatibility for DOS and Win16 applicationsfor DOS and Win16 applications

Chapter SummaryChapter Summary Of these subsystems, only Win32 is Of these subsystems, only Win32 is

crucial to the functioning of crucial to the functioning of Windows XP as a wholeWindows XP as a whole

The other subsystems start up only The other subsystems start up only as they are neededas they are needed

Windows XP includes some Windows XP includes some interesting additional application interesting additional application management facilitiesmanagement facilities

Documents

Chapter Eleven Windows XP Professional Application Support