Chapter 10 - Chapter 10 - Management of Management of Network FunctionsNetwork Functions

Ivy Tech State College Northwest Region 01

CIS106 Microcomputer Operating Systems

Gina RueCIS Faculty

See Illustration p.225 2

Introduction - Introduction - Management of Network Management of Network FunctionsFunctions

• Organizations are expanding networks Organizations are expanding networks with more computing deviceswith more computing devices

• Two problems:Two problems:– demand placed on data communication demand placed on data communication

by many hardware interconnectionsby many hardware interconnections

– pressure for networks to operate with pressure for networks to operate with greater reliability and faster speedgreater reliability and faster speed

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History - History - Management of Network Management of Network FunctionsFunctions

• Early systems focused on sharing hardware Early systems focused on sharing hardware resourcesresources

• Physical network, coupled with a NOS, Physical network, coupled with a NOS, allowed increased availability of resources & allowed increased availability of resources & spread cost among usersspread cost among users

• Data and information sharing increasedData and information sharing increased

• NOS were enhanced for centralized NOS were enhanced for centralized information resourcesinformation resources

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History - History - Management of Network Management of Network FunctionsFunctions

• Applications collectively known as Applications collectively known as groupware, use a set of technologies groupware, use a set of technologies called distributed processingcalled distributed processing– Provide even greater access to Provide even greater access to

centralized informationcentralized information

– Assist users who need to work together Assist users who need to work together to complete tasksto complete tasks

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Comparison of Network &Comparison of Network &Distributed SystemsDistributed Systems• Network Operating System Network Operating System (NOS) developed (NOS) developed

from a need to providefrom a need to provide– global resource allocationglobal resource allocation

– global process managementglobal process management

– complete transparency of network access for users complete transparency of network access for users and their sites’ OS (known as local OS)and their sites’ OS (known as local OS)

• To a local OS, the NOS is the actual server To a local OS, the NOS is the actual server performing the task, when in reality it is the performing the task, when in reality it is the instrument for the actual taskinstrument for the actual task

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Comparison of Network Comparison of Network andandDistributed OSDistributed OS• NOS does not consider memory, process, NOS does not consider memory, process,

device, or file management from a global device, or file management from a global viewpointviewpoint

• NOS sees them as local functions that must NOS sees them as local functions that must interact with each other but do not direct each interact with each other but do not direct each otherother

• Global control of all assets is a need that led to Global control of all assets is a need that led to the development of a Distributed Operating the development of a Distributed Operating System (DOS - not to be confused with MS-DOS)System (DOS - not to be confused with MS-DOS)

See Fig. 10.1 & 10.2 p. 226-227, Table 10.1 p.228

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Comparison of Network Comparison of Network and and Distributed OSDistributed OS• Major difference between NOS and Major difference between NOS and

DOS is in how each views and DOS is in how each views and manages local and global resourcesmanages local and global resources– NOS build on capabilities provided by the NOS build on capabilities provided by the

local OS and extend it to satisfy new local OS and extend it to satisfy new needsneeds

– DOS views systems resources as globally DOS views systems resources as globally owned and manages them as suchowned and manages them as such

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Distributed Operating Distributed Operating System (DOS) System (DOS) DevelopmentDevelopment

– DOS manages the entire group of resources DOS manages the entire group of resources within a network in a global fashionwithin a network in a global fashion

– Viewed as a logical single system rather than a Viewed as a logical single system rather than a collection of independent cooperating systemscollection of independent cooperating systems

– Control & allocation of resources are negotiated Control & allocation of resources are negotiated & compromised among peers sites in the DOS& compromised among peers sites in the DOS

•Advantage is its ability to support file Advantage is its ability to support file copying, email, & remote printing with copying, email, & remote printing with installation of special driver softwareinstallation of special driver software

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DOS DevelopmentDOS Development– Memory ManagementMemory Management

•memory allocation and deallocation will depend memory allocation and deallocation will depend on the selected global scheduling and sharing on the selected global scheduling and sharing schemesschemes

•similar to local OS, but it must be extended to similar to local OS, but it must be extended to accept requests for memory from both local & accept requests for memory from both local & global resourcesglobal resources

•uses virtual memory, when an application tries uses virtual memory, when an application tries to access a page not in memory, a page fault to access a page not in memory, a page fault error will occur & the memory manager will error will occur & the memory manager will automatically bring that page into memoryautomatically bring that page into memory

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DOS DevelopmentDOS Development– Process ManagementProcess Management

•provides policies & mechanisms to manipulate provides policies & mechanisms to manipulate processes to provide real-time priority execution processes to provide real-time priority execution and the state of executionand the state of execution

•each CPU in the network is required to have its each CPU in the network is required to have its own kernel that manages low-level operation on a own kernel that manages low-level operation on a physical devicephysical device

•two ways of looking at the DOS:two ways of looking at the DOS:– process-based: large collection that includes all the process-based: large collection that includes all the

system processes & resourcessystem processes & resources– object-based: clumps types of hardware with its object-based: clumps types of hardware with its

necessary operational software into unitsnecessary operational software into units

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DOS DevelopmentDOS Development– Process-based DOS Process-based DOS

• provides for process management through client/server provides for process management through client/server processes synchronized & linked together through processes synchronized & linked together through messages & ports (also known as channels or pipes)messages & ports (also known as channels or pipes)

• high level of cooperation & sharing of actions and data high level of cooperation & sharing of actions and data maintained by the system sites maintained by the system sites

• synchronization is key by using primitives such as synchronization is key by using primitives such as “send and receive”“send and receive”

• interrupts, which cause a processor to be assigned to interrupts, which cause a processor to be assigned to another process, are represented as messages that are another process, are represented as messages that are sent to the proper process for servicesent to the proper process for service

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DOS DevelopmentDOS Development– Object-based DOSObject-based DOS

• instead of being made up of resources & processes, instead of being made up of resources & processes, the system is viewed as a collection of objects (all pc the system is viewed as a collection of objects (all pc components)components)

• process management becomes object managementprocess management becomes object management

• capability lists for objects capability lists for objects

• synchronization & communication support are part synchronization & communication support are part of the kernel portion of a DOS of the kernel portion of a DOS

• uses different communications primitives which are uses different communications primitives which are either synchronous or asynchronouseither synchronous or asynchronous

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DOS DevelopmentDOS Development

– Object-based and process-based Object-based and process-based differencedifference• objects contain all of their state objects contain all of their state

informationinformation

• information is not stored separately in information is not stored separately in another part of the systemanother part of the system

• information does not need to be stored in information does not need to be stored in a process control block or other data a process control block or other data structure separate from the objectstructure separate from the object

See Fig. 10.4 p. 235 14

DOS DevelopmentDOS Development

– Device ManagementDevice Management• devices must be opened, closed, read devices must be opened, closed, read

from, and written tofrom, and written to

• status bit must be set or cleared & status bit must be set or cleared & parameters must be initializedparameters must be initialized

• can be done on a global, cluster, or can be done on a global, cluster, or localized basislocalized basis

• allocation is successfully completed after allocation is successfully completed after examination of the device’s status examination of the device’s status

See Fig. 10.5 p.236 15

DOS DevelopmentDOS Development

– Device ManagementDevice Management•process-based DOSprocess-based DOS

– all resources are controlled by all resources are controlled by servers that accept requests for servers that accept requests for service by othersservice by others

•object-based DOSobject-based DOS– physical device viewed as an object physical device viewed as an object

manipulated by a set of operations to manipulated by a set of operations to designate device functionsdesignate device functions

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DOS DevelopmentDOS Development– File ManagementFile Management

• goal of distributed file management is to give goal of distributed file management is to give users the illusion of a single local file systemusers the illusion of a single local file system

• main function of a DOS file manager is to provide main function of a DOS file manager is to provide transparent mechanisms to find, open, read, transparent mechanisms to find, open, read, write, close, create, & delete files in the networkwrite, close, create, & delete files in the network

• similar environment to distributed databasesimilar environment to distributed database– controls to provide efficiency, consistency, and controls to provide efficiency, consistency, and

reliabilityreliability– Detection & correction, prevention, & Detection & correction, prevention, &

avoidance are used to deal with deadlockavoidance are used to deal with deadlock

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DOS DevelopmentDOS Development– Communication ManagementCommunication Management• unique to networked systems, stand-alone has no unique to networked systems, stand-alone has no

need for communication managerneed for communication manager

• provides policies & mechanisms to achieve intrasite provides policies & mechanisms to achieve intrasite & intersite communication among concurring & intersite communication among concurring processesprocesses

• process is registered or logged in the networkprocess is registered or logged in the network

• ports are usually associated with physical buffers & ports are usually associated with physical buffers & I/O channels, & represent assets that must be used I/O channels, & represent assets that must be used wiselywisely

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DOS DevelopmentDOS Development– Communication ManagementCommunication Management• process-based DOSprocess-based DOS

• interprocess communication is transparent to the userinterprocess communication is transparent to the user

• network manager has functions of controlling network manager has functions of controlling allocation of ports to processes, etc.allocation of ports to processes, etc.

• object-based DOSobject-based DOS• makes both intermode & intramode communications makes both intermode & intramode communications

among cooperative objects easyamong cooperative objects easy

• knowing the location of the receiver is not necessary, knowing the location of the receiver is not necessary, network managers: send, receive, reply, requestnetwork managers: send, receive, reply, request

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NOS DevelopmentNOS Development

– True operating systemTrue operating system•memory, processing, file, & device memory, processing, file, & device

managementmanagement

•NOS typically run on servers and NOS typically run on servers and perform services for network nodes or perform services for network nodes or workstations called clientsworkstations called clients

•NOS focuses on user interactionNOS focuses on user interaction– NOS examples are: Novell Netware, Microsoft LAN NOS examples are: Novell Netware, Microsoft LAN

manager, IBM’s LAN Server, Windows NTmanager, IBM’s LAN Server, Windows NT

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NOS DevelopmentNOS Development Important Features in a NOSImportant Features in a NOS– 16-bit or 32-bit software to take advantage of modern 16-bit or 32-bit software to take advantage of modern

processorsprocessors

– LAN standards: Ethernet, token ring, Localtalk, and Arcnet LAN standards: Ethernet, token ring, Localtalk, and Arcnet

– heterogeneous: they support workstations with different heterogeneous: they support workstations with different OSOS

– use a variety of third-party hardware devices and software use a variety of third-party hardware devices and software applicationsapplications

– must be efficient and secure with core components to must be efficient and secure with core components to enable multiple clients quick access & resources, & enable multiple clients quick access & resources, & securitysecurity

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NOS DevelopmentNOS Development Major Functions of NOSMajor Functions of NOS– allow users to access resources at a allow users to access resources at a

remote site; Internet Telnetremote site; Internet Telnet

– security, access to resources with user security, access to resources with user id & passwordid & password

– procedure to transfer files from one procedure to transfer files from one computer to another; Internet FTP (file computer to another; Internet FTP (file transfer protocol)transfer protocol)

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SummarySummary

• Network operating systems (NOS) Network operating systems (NOS) were developed to link free standing were developed to link free standing independent systemsindependent systems

• Distributed Operating Systems Distributed Operating Systems (DOS) were developed to take full (DOS) were developed to take full advantage of global resources advantage of global resources available to all connected sitesavailable to all connected sites

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SummarySummary

• NOS & DOS requirements:NOS & DOS requirements:– security from unauthorized users yet accessible security from unauthorized users yet accessible

to authorized users to authorized users

– communication linkscommunication links

– monitoring system resources:monitoring system resources:• memorymemory

• processorprocessor

• devicesdevices

• filesfiles