Distributed System Services Prepared By:- Monika Patel.

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 kernel Communication. 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 Systems By Dr. Mads Haahr,Trinity College, Dublin. [5]Operating System concept by Silberschatz,Galvin,Gange,ch -3 operating System structure.

Thank You