Operating SystemsSERVICES

BARNALI CHAKRABARTY

What is an Operating System ?

Features of Operating System

Multi user

Multiprocessing

Multitasking

Multithreading

Real time

Classification of Services[Chow07]Primitive Services –fundamental functions

that the kernel must provide

Services by System Servers- services that need not reside in the kernel but are still essential

Value Added Servers –services that are not essential in implementation but are useful in supporting distributed applications

Primitive Services

Communication- Exchange of Information between processes

Synchronization- Coordination of Events

Services by System ServersName Server - used to locate users, processes

or machines

Network Server –used to translate addresses and locations obtained from Name server

Time Server-synchronization of processes to maintain a total order of event occurrences

File Server- managing shared file system resources

Value Added ServicesWeb Server – accepts requests from the

clients , processes it and returns a response

Group Server –manages creation and termination of groups of interacting processes

Classification of Services [Galvin05]Services that are helpful to users

Services for efficient operation of system

Operating System Services that are helpful to usersUser InterfaceProgram ExecutionI/O OperationsFile System OperationsError Detection

User Interface

The means by which the user interacts with the system

Consists ofInputOutput

Program Execution

• Loading• Running • Execution

I/O Operations

The communications between the computer and the outside world

File System Manipulation

Programs need to read and write files and directories, create and delete them, search them, list file Information

Error Detection

OS needs to constantly monitor possible errors and

should take an appropriate action to rectify the error

Services for efficient operation of systemResource AllocationAccountingProtection and Security

Resource Allocation

Resource allocation must be properly done when multiple users or multiple jobs running concurrently.

Accounting

OS keeps track of what kind of resources used, how many users etc

Protection and Security

• Ensuring that all access to system resources is controlled

• Access to the system from outsiders requires user authentication

WebOS: A Framework of OS services for wide area Applications[A.Vahdat97]Global Naming

Wide-Area File System

Security and Authentication

Process Control

Privacy as an Operating System Service [S.Iosannidis06] Approach 1.Transparent, privacy-providing storage and

network

2. Privacy-enhanced system calls

3. Privacy Libraries

4. Privacy-policy Management

System Support for Many Task Computing[E.V.Hensbergen,08]

The paper deals with issues of scale by leveragingthe large number of nodes to spread operating systems

services and components across the machine, tightly coupling the operating system. The authors plan on provisioning nodes to provide workload execution, aggregation, and

system services, and dynamically re-provisioning nodes as necessary to accommodate changes, failure, and

redundancy.

Future Work

Implementation and Development of Liquid Operating system, which is spontaneous and adaptive to dynamically meet the changing requirements of the user.

References[1]http://www.webopedia.com/TERM/o/operating_system.html[2]Wikipedia[3]Distributed Operating Systems and Algorithm Analysis, Andy

Chow & Theodore Johnson,1997[4] Operating System Concepts , Silberschatz, Galvin and

Gagne ,2005 [5] WebOS: Operating System Services for Wide Area

Applications,Amin Vahdat et al,1997[6] Privacy as an operating system service ,Ioannidis ,S;

Sidiroglou ,S; D. Keromytis,A;Proceedings of the 1st USENIX Workshop on Hot Topics in Security,2006

[7] System support for many task computing, Van Hensberger, E.; Minnich, R.;Many-Task Computing on Grids and Supercomputers, 2008. MTAGS 2008. Workshop on 17-17 Nov. 2008 Page(s):1 - 8