Distributed System Services

Prepared By:-Monika Patel.mpatel56@student.gsu.edu

Overview What is operating system? Layers of O.S. Basic Services provided by O.S. Fundamental Services. Primitive Services. Services by System Servers. Value Added Services.

What is an operating system? (ch-10,OS,Nell dale, john lewis)

An operating system Is a service provider. Manages computer resources, such

as memory and input/output devices.[1]

Provides an interface through which a human can interact with the computer.[1]

Continued Allows an application program

to interact with other system resources[1].

Layers of Computer systems (ch-2,2.1,OS Overview)

Basic Services Provided By O.S (Ch-3,3.12,OS structure, Silberschatz ,Galvin,Gange) Program development

Editors and debuggers. Access to I/O devices. Controlled access to files System access Program execution

Continued (Ch-3,3.12,OS structure, Silberschatz ,Galvin,Gange) Error detection and response

Internal and external hardware errors

Memory error. Device failure.

Software errors Arithmetic overflow.

Continued (Ch-3,3.12,OS structure, Silberschatz ,Galvin,Gange) Accounting

Collect usage statistics. Monitor performance. Used to anticipate future

enhancements. Used for billing purposes.

Fundamental Services (ch-2,2.3,Distributed OS& Algorithms,Randy chow,Theodore johnson.) Three fundamental services are

there . System Primitives.

Services By system servers.

Value Added Services.

What is kernel? (ch-2,2.1,OS Overview) Portion of operating system that is always in main memory Contains most-frequently used

functions Also called the nucleus Good performance of the kernel is

very important

Fundamental function of kernelCommunication.

Synchronization.

Processor multiplexing.

Primitive Services (ch-2,2.3,Distributed OS& Algorithms,Randy chow,Theodore johnson.) Primitive services are those that

must be implemented on kernel of each node in the system.

In Distributed system when communicationis done through message passing set of primitives for send and receive must be defined and implemented.

Continued Synchronous Communication Send And receive primitives

can be synchronous or asynchronous.

Synchronization Servers

What is Process Server? It manages creation, deletion and tracking of processes by allocating

the resources like memory,processing time etc.

Services by System Servers ch-2,2.3,Distributed OS& Algorithms,Randy chow,Theodore johnson.) What is System Services? The services which can be

implemented anywhere in the system and performs the functions which is basic to the operation of a distributed system.

Continued What is System Server? The service provider of the

system is called system server.

Continued To achieve transparency in

Distributed System System server mappes physical objects with logical system names.

Name server Used to locate users ,processes

and machines.

Continued Directory Server It is used in conjuction with files

and communication ports.Network server

Name server translation, selection of paths ,actual routing of information is done by network server.

Continued Time Server It is used for synchronizing and

scheduling of hardware and software activities.Physical Clocks.Logical Clocks.

Servers involved in managing shared system resources. File servers. Print servers. Authentication server. In Short System Server

provide services for managing processes,files and process communication.

Value Added Services ch-2,2.3,Distributed OS& Algorithms,Randy chow,Theodore johnson.) Services that are not needed in the

implementation of a Distributed System But useful in supporting Distributed Application.

Used To increase the computational performace and enhacement of fault tolerance or by need for cooperative activities.

Continued Group Server It manages the creation and

termination of group activities. Responsible for Group

addressing ,communication ,contain information about membership, member privileges and admission policies..

Continued. Web server is also the good

example of a value added server.

Refrences:-[1]Computer science illuminated ,second

edition,By Nell dale,John lewis.[2]Distributed operating systems &

Algorithms,By Randy chow,Theodore johnson.

[3]Operating System Overview ,Chapter 2.

Continued[4]Two-Hour Introduction to Operating

SystemsBy Dr. Mads Haahr,Trinity College,

Dublin.[5]Operating System concept by

Silberschatz ,Galvin,Gange,ch -3 operating System structure.

Thank You