Windows NT A Distributed ArchitectureAgendaFeaturesDesign goals of Windows NTWindows NT ArchitecturePowerPoint PresentationExecutive LayerObject ManagerSecurity Reference MonitorProcess ManagerVirtual Memory Manager(VMM)VMM - cont’dI/O ManagerI/O Manager - cont’dKernel LayerHardware Abstraction LayerEnvironment subsystemWin32 SubsystemWin32 Subsystem - cont’dOS/2 SubsystemMS-DOS EnvironmentMS-DOS Environment - Cont’dWindows 16-Bit EnvironmentWin 16-Bit Environment – cont’dSlide 25BibliographyAny Questions1 Windows NT Windows NT A Distributed ArchitectureA Distributed Architecture Professor: Mohamed Khalil CSE 8343 GROUP-A5 Dhaval Sanghvi Amit Sharma Ali Abbas (Video-Tape)2AgendaAgendaFeaturesDesign goals of Windows NTArchitecture•Three LayersUpper Layer - ExecutiveMiddle Layer - KernelLower Layer - Hardware Abstraction LayerEnvironment SubsystemSummaryBiblography3Features Features Preemptive MultitaskingSupport for Symmetric MultiprocessingIntegrated Networking servicesClient/Server ArchitectureSupport for several file systemsVirtual Memory ManagementSupport for 2 GB linear space for application and also 2GB for OS4Design goals of Windows NTDesign goals of Windows NTExtensibility PortabilityReliability CompatibilitySecurityPerformanceScalability Localization5Windows NT ArchitectureWindows NT ArchitectureWindows NT is a modular operating system composed of simple modules : kernel mode and user mode.Kernel Mode composed of mainly 3 layers:Upper layer - Executive layerMiddle layer - The kernelLower layer - Hardware Abstraction Layer(HAL)User Mode is composed of environment subsystems.6Architecture - cont’d7Executive LayerExecutive LayerEach component of NT Executive provides a set of API’sSome API’s are designed to be invoked by user-mode processes.Some API’s are visible only in the kernel mode inside the ExecutiveNT’s API’s are flexible enough to implement a wide range of operating system environments.NT’s Executive has six subsystems - Object Manager, Process Manager, Virtual Memory Manager, Security Reference Monitor, Local Procedure Call Facility, I/O subsystem8Object ManagerObject ManagerAn object is a representation of a conceptual or physical entity in the system.Examples of Objects:–Files–Directories–Processes–Threads–Synchronization Objects (semaphores, mutexes, events, timers)–Virtual Memory objectsMostly everything passed around and processed within NT is represented as an object.9Security Reference MonitorSecurity Reference MonitorChecks for proper authorization before granting access to objectsObject Manager is a customer of a SRM: it asks SRM if a process has the proper rights to execute a certain type of action on an object.Implements auditing functions to keep track of attempts to access an objectImplements high level security:–Resource owners must be able to control who has access to it.–Unique user name and password identification–Audit trail of successful and unsuccessful attempts–Protection from unauthorized tampering of files10Process ManagerProcess ManagerCreates,deletes and modifies processes and threadsDoes not dispatch or schedules any work. This is done by the kernelA process is represented within NT by a process objectProcess Object = (process’ virtual address space, resources visible to the process, process threads)NT does not maintain parent-child information between related processes.11 Virtual Memory Manager(VMM)Virtual Memory Manager(VMM)Implements a fetch policy(when the pager brings a page from disk to memory). Uses a demand paging algorithm with the locality of reference(“clustering”)Implements shared memory segments(used by LPC to transfer large messages)Certain parts of the VMM are processor dependent (e.g. page table entries,page size,virtual address translation) Manages file system drivers,device drivers and network drivers12VMM - cont’dVMM - cont’dDrivers can be dynamically loaded, unloaded, started and stopped without rebooting the systemMultiple installable file systems including MS-DOS FAT ( File Allocation Table), High Performance File System(HPFS), the CD-ROM file system and the NT File System(NTFS)13I/O ManagerI/O ManagerMapped file I/O capabilities for image activation, file caching and application usePacket driven I/O system. Every I/O request is represented by an IRP (I/O Request Packet) that moves from one I/O system component to the otherManages buffers for I/O requestsProvides time-out support for driversRecords which installable components are loaded in the system14I/O Manager - cont’dI/O Manager - cont’dNTFS extends MS-DOS FAT with HPFS with:–Quick recovery of disk data after system failure–Ability to handle very large files (17 billion GB)–Security features (e.g. execute only files)–Support for POSIX OS environments–Features for future extensibility(e.g. transaction-based operations to enhance fault tolerance,user-controlled file version numbers, flexible options for file naming and file attributes)15Kernel LayerKernel LayerSchedules threads to run.Handles hardware interrupts and dispatches them to appropriate drivers and threads.Handles software and hardware generated exceptions (e.g. writing to non-existing memory position, memory parity errors)Graceful system shutdown and restoration after power failureProvides an API to the executive to kernel-managed objects (e.g. events, mutexes, semaphores and timers)16Hardware Abstraction LayerHardware Abstraction LayerIsolates the kernel from hardware variationsExports an API to upper layers to handle hardware dependent issues such as:–Processor initialization( support for SMP computers)–Instruction cache and data cache–Device driver support(e.g. bus addressing, interrupt control, DMA functions)–Timing and interrupt functions–Firmware interface functions–Low level error handling17Environment subsystemEnvironment subsystemUser mode process that provides services to applicationsThese services emulate the behavior of a specific OSConverts requests made by an application to requests that NT’s kernel mode component understandImplemented using Client/Server model:–Application Client–Environment subsystem Server18Win32