client server technology

Client Server Technology

UNIT -1

Definition

Client requests to the server for data or

information

Server serves the data or information

Fulfils the requirements of the client & sends

the results back to the client

Client performs some logical operations

Definition

Client Server Computing (CSC) is that Server Operating

System (OS) accepts requests for data from Client OperatingSystem & returns the results(services) to the Client.

Client manipulates or calculates data and presents the results

to the user.

What is Networking?

Connecting computers so that they can share

files, printers, applications, and other computer

related resources.

Advantages:-

File server

Network printer

Application servers

Centralized servers

Different types of networks

Local Area Networks(LAN)

Wide Area Networks(WAN)

Metropolitan Area Network(MAN)

Internet

Different types of Networking

Peer-to-Peer Networking

Workgroup Networking

Server-based Networking

Terminal-based Networking

History

1969, the Department of Defence USA built

ARPANet(Advanced Research Project Agency).

For sharing of data research centres.

ARPANet started with just 4 computers on the network

University Of Los

Angeles

History

ARPANet converted into:

-MILNET – Military Network – which was only for the military

network.

New smaller ARPANet, which had the non military sites.

1971, 2 dozen sites attached to ARPANet.

1972, 40 different sites attached to ARPANet.

History

1980, another network called CSRNet – Computer Science

Research Network was linked to ARPANet.

CSRNet was created to connect several independent

networks.

This was the birth of internet and networking

1986, the NSF built own network National Science Foundation

(NSF)Net which was also linked to other main networks.

Powerful network in terms of speed

History

Networking Technology developed, new networks all linked

to the ARPANet, Computer Science Research Network

(CSRNet) and NSF Net.

Networks connected together is known as the ‘Internet’.

ARPANet was finally shut down in 1989

Evolution of Client

Server Concept

Evolution

Evolution [growth] of networking

Various reasons can be broadly categorized into following:

1. Hardware Trends

2. Software Trends.

3. Networking Trends.

Hardware Trends

Hardware Trends can further be divided into the

following:

-Power/Speed

-Chips [Micro Processor]

-Memory

-Storage Devices

-Power/ Speed 17

-Chips

Chips used were 386, 486 [in MHz].

Now a days chips are available in GHz such as 1.0,2.0,

1.2,1.4,1.7,2.0, Xeon etc..

-Chips

AMD’s powerful chips Athlon, Pthlon,

Sympthon etc.,

Processors are categorized:-

P1 -> 33Mhz ---166 Mhz.

P2 ->200Mhz ---450Mhz.

P3 ->500Mhz ---1.4Ghz.

P4 ->1.7Ghz --- 2.0,2.1,2.4,Xeon, AMD’s

[Athlon, Pathlon].

i3, i5, i7 -> 1.7Ghz --- 3.3Ghz

-Memory 20

Memory

Hard Disk Drive

(H.D.D)

RAM for different Processors

Extended

Data Output

Static

Dynamic (SD)

Dual Data

Rate(DDR)

Storage Devices

Storage devices categorized into two main types:

1. Fixed Storage Devices.

-H.D.D

-Floppy Disk Drive

-Compact disk (C.D) Drive

-Digital Versatile Disk (DVD) Drive

2. Removable Storage Devices

-Pen Drive

-Universal Serial Bus (USB) Hard Disk

Storage Unit

4 Bits = 1 nibble

8 Bit =1 byte

1024 byte = 1KB [ Kilo byte ]

1024 KB = 1MB [ Mega Byte ]

1024 MB = 1GB [Giga Byte ]

1024 GB = 1TB [ Tera Byte]

1024 TB = 1 PB [ Pera Byte ]

1024 PB = 1 Exabyte

1024 EB = 1Zettabyte

1024 ZB = 1 Yottabyte

1024 YB = 1 Brontobyte

1024 BB = 1 Geopbyte

Software Trends

1. Graphical User Interface (GUI) Concept.

2. RDBMS.

3. Multi Threading Processing.

1. GUI concept

GUI is Graphical User Interface.

WYSWYG [What You See is What You Get].

2. RDBMS

RDMBS is Relational DataBase Management System.

Manage & Maintains Large DataBase.

E.g. Oracle, FoxPro, SQL, MS Access.

Data is stored in Tabular format.

Development in C/S or networking, it is possible for various

users to access the same data at a time.

2.RDBMS 28

3. Multi-Thread Processing

A thread is the smallest unit of process or an execution

Multithreaded S/w such as Microsoft LAN manager Network

Operating S/w MS 2003 Server…etc.

Support multiple threads of execution the printer, one the

keyboard I/O and another executing application code.

Multithreading support allows the S/w to make more

efficient use of the H/w.

Networking Trends

Connects two or more computers for data or

device sharing is known as networking.

Network is an Inter Process Communication (IPC)system in which data or message transferred b/w

process and threads

Network Architecture has rules and protocols for

how transfer occurs within the architecture

Networking Trends

Different H/w and S/w can communicate as long

as they use the same protocols and data

formats.

The earliest micro LAN’s were easy to install.

Provides Security and Authentication of Data

Access.

Categories are LAN, WAN, MAN or Virtual Private

Network (VPN)

Advantages of

CST computing/

need & motivation

for C/S Approach

Advantages

Networking plays a very important role.

It is life line of today’s modern offices.

LAN to intranet to internet.

Advantages

Connectivity.

Sharing Devices.

Flexibility and Scalability.

Centralized Control.

Faster Delivery of Systems.

Resource Utilization.

Reduction in Network Traffic.

Advantages -Connectivity

Connectivity is to connect other computers or resources.

Provides the interactivity share our data or information among

multiple computers.

We can also share our files on the network.

Advantages -

Connectivity

‘File Sharing’

‘Resource Sharing’

‘Remote Accessing’.

Advantages -Connectivity

Accessing a Remote Computer through Network

All these facilities are provided by the ‘Network

OS’ or the ‘Server OS’.

Advantages -Sharing

Devices In CST we share various devices

Sharing of resources is done through networking

Advantages -Flexibility

and Scalability Segmenting the application task, an organization can easily

add a new technologies.

Enhance existing technologies without interruption

Add a new computer or node on a network also removed.

Advantages -Flexibility

and Scalability

Add or remove Computers

Data access through networking is easy

Advantages -Centralized

Control

Centralized facility is the one in which data is

transmitted through channel.

In past centralized facility was difficult toimplement and maintain.

Client Server Technology (CST) allows facilities to

combine Centralized and Decentralized

Architectures.

Control Decentralized portion of the system consists of the

processing done on the client and is the

responsibility of the business and user.

Centralized portion of the system consists of the

processing performed on the server and is the

responsibility of Internet Securities professional as

are the link to the server.

Control Server maintains an Intelligent Database with rules and

security

E.g.: Backup and Recovery procedures are centralized

Advantages -Faster Delivery of

Systems Workstation environment, powerful multitasking CPU

availability, single user database and integrated testing tools.

All combine to provide the developer with considerable

productivity improvements in a lower cost environment.

Server application functionality, database, and network

services is transparent and almost automatic.

Network components & communication channel or media

are helpful to perform faster delivery on networks.

Advantages -Reduction in Network

Traffic Excessive network traffic is one of the most common causes

of poor system performance

Designers take special care to create to a avoid such

situation

Reduction in Network

Traffic

In client server model, it is possible to reduce the

network traffic and

Provide frequent transmission of data between computers through a routers and fiber optic

cable.

Client Server

Environments

The Environments

Client Server is a network architecture.

Components: The Client and The Server.

Client runs an application using Graphical

Interface (G.I)

Through this application can request the Server.

The Environments

Server accepts the request and responds.

Servers are classified as Web Servers, File Servers, Terminal

Servers, Mail Servers etc.

Servers may have different size, OS or different purpose

Basic architecture remain same

The Environments

Example of CS Technology is the internet

Internet are stored on a Server machine

User requests for the application to the Server

Server searches

Characterization

of Client/Server

Computing

COMPONENTS OF CLIENT SERVER TECHNOLOGY

/ COMPUTING

Components

There are mainly three components.

1. The Client

2. The Server

3. The Network

The Client

Client is the desktop machine

Micro or Workstation computer

Network s/w sends the request to the server

Accepts result form Server and passes result back to Client

Client may perform some application logics

The Server

Server machine is designed for server

functionality

Comparison to desktop machine

Increased Memory capabilities

Increased Storage capabilities

The Server

Increased processing power [ through multi

processor technology].

Improved Reliability with built in reliability featuressuch as:

-Uninterruptible Power Supply

-Fault Tolerance

-Disk Mirroring

The Server

Evaluating server h/w:-

1. Reliability

2. Availability

3. Flexibility

1. Reliability

Server Machine is considered as brain of

networking

Directly or Indirectly controls whole network

Responsible for speed and performance of

network

Server machine has to be very reliable

1. Reliability

The reliability is checked by the fact that how

often does it fail?

What is the mean time between failures?

Does it perform automated regular data

backups?

Does it has any strategy to deal with power cuts?

All these questions and many important features

of server make it a reliable machine.

2. Availability

Availability refers?

Systems have self healing routines

Fault tolerant alarms

Specific configuration rebooted from a remote

Flexibility & Scalability

The application tasks, an organization can easily

migrate to new technologies or enhance existing

technologies with or no interruption

Application does not have to be redesigned to

use a new interface s/w or be moved to new

platform

We can always add a new computer or remove

a node from the network

Data access through networking is also very easy

through a GUI

3. The Network

Network connecting devices

Managed and maintained by network

Managed I/O processes

2. Distributed Working

Distributed computing is a method of computer

processing

The Role of

ClientUNIT II

The Client

Request to Server

Network Operating System(NOS) Software who

helps in making the request and forwarding therequest to the server

NOS software translates or adds the specifics

required

IPC (Inter Process Communication).

The Client

Processes might be on the same computer

Service provided by the NOS is redirection.

Service intercepts client workstation Operating

System(OS) calls redirects them to the Server OS

The Client

Request for files, printers, serial devices,

application programs

Redirected to the correct server location.

Possible for some services to provided by the

client workstation.

The Client

Local disk drivers may be labelled A: or C: and the

remote drives by label Z:, D: or anything else.

How does redirection works ?

Requests for drive A: or C: is passed through to the

local file system by the redirection software.

The Client

Requests for other drives are passed to the server

operating system.

Printers are accessed through virtual serial ports

NOS requester software constructs the Remote

Procedure Call.

Application programming interface (API) calls to

the NOS server.

The Client

NOS server then processes the request as it is were

executed locally and response back to the

application.

Novell commercialized this redirector concept for

the INTEL and MS DOS platforms and it has been

then adopted by all NOS.

Dynamic Data Exchange

Provides automatic information exchange

It provides the linking

Windows alternatives to DDE

DDEML stands for Dynamic Data Exchange Management

Library

Provides better interface then DDE

Mediator b/w called and calling app

Calls for services are made to DDEML

Passes data b/w application from different

vendors

Example- Chart from excel can be linked to a

database to provide the latest data whenever

the chart is referenced.

Dynamic Link Library(DLL)

File containing executable routines that can be

loaded on demand by an application.

Providing standard services for many different calling applications

DLL are loaded into RAM only when needed by

the calling application

DLL are files that have the extension .dll

Object Linking &

Embedding

Technique or Concept which you can link or

embed the object with one another

Allows user to build compound document

Document is treated as a Collection of objects

rather than file

Double clicking on an object starts up the original

application software and allows the user to

modify the object.

Object Linking &

Embedding

Create and edit documents by using different

applications

For example you can embed bitmap images, sound clips, spread sheet files and other objects in

Microsoft Word documents.

Basically this feature provides us with ‘Linking’ and

‘Embedding’

Object Linking &

Embedding

Linking:-

A link is added in a document

Link points to the source data stored somewhere

Linked objects are stored in the document as a

path to the original linked data

Changes in the data will be reflected in the

original data also.

Object Linking &

Embedding

Embedding:-

Embedding adds one document directly into

other document

Embedded objects are stored with the document

that contains them

Change in the data in embedded file is not

reflected in the original data

‘CORBA’ stands for Common Object Request

Broker Architecture

Component architecture developed by the Object Management Group and its member

companies.

Technology for creating, distributing and

managing component programming

Designed to provide interoperability b/w

applications in heterogeneous distributed

environments.

CORBA is not supported by Microsoft

Instead has developed its own distributed object

management architecture

The architecture developed by MS is called

COM(Component Object Mode) or

DCOM(Distributed COM)

HOW CORBA works?

Requests service through an Object Request

Broker (ORB)

ORB allows components of distributed applications

Applications communicate without knowing

where the application is located in network

HOW CORBA works?

ORB’s are in fact the middleware s/w that enables

client and server programs to establish session

with each other.

Independent of their location in the network or

their programming interface

Client issues a call which is intercepted by the

HOW CORBA works?

ORB takes call and is responsible for locating a

server machine that is able to process the request

Once it has located the server, it invokes the object’s methods and passes any parameters

submitted by the client

The requests are then processed and the result is

sent back to the client

HOW CORBA works?

ORB’s communicate among themselves using

GIOP(General Inter ORB Protocol)

They also Communicate through the IIOP(Internet Inter ORB Protocol).

So ORB’s can fulfill the request of any client

CORBA vs OLE

CORBA is specification of Object Management

Group(OMG)

OLE (Object Linking Embedding) focuses on data sharing b/w applications on a single desktop

CORBA addresses cross platform data transfer

and moving object over networks

CORBA vs OLE

CORBA support enables windows and UNIX clients

to share objects.

A word processor operating on Windows platform can include graphics generated from UNIX

workstation.

RPC(Remote Procedure

Message passing programming technology

developed by Sun Microsystems and extended by

the Open Software Foundation (OSF)

Applications to execute procedures and interact

with services on a remote computer on network

CST on MS windows server 2000 and window NT

platforms is enabled using RPC’s

How it works?

RPC is to pass messages b/w components of a

distributed application that are located on

different computers on a network.

Local Procedure Calls(LPC’s) provide a

mechanism for enabling different parts of an

application located on a single computer to

communicate with each other.

How it works?

RPC’s provide a mechanism through which

computers on different networks can

communicate with each other

In fact RPC’s use a wide variety of IPC

mechanisms such as NetBIOS (Network Basic Input

Output System), windows sockets, mail slots to

establish connections between the RPC client

and the RPC server

How it works?

The Remote Procedure Call service (RPC service)

is a component of the Windows NT executive

running in kernel mode

It is responsible for message passing b/w the client

and the server components of a distributed

application

Message is passed b/w client server application

such as MS outlook express and MS exchange

server

How it works?

On a windows NT based network the server first

registers itself with the RPC Locator service

The client part of the application which is on the local computer can then query the RPC locator

service to determine the location of the required

server part.

The RPC server located server is a part of the

operating system located on the client machine.

How it works?

A process called the remote procedure stub then

packages the clients function call into a suitable

RPC message and sends it to the remote computer using RPC run time process

At the remote machine a process called the

application stub receives the RPC message

How it works?

It unpackaged the message into a function call

and executes it, returning any resulting values to

the client part in a similar fashion.

From the view point of the client part of the

application, the server part appears to be on the

same computer.

CST Application

CST Applications

Applications that run on a network, technically

different from application running on a local

machine.

Applications which are specially designed to run

on network are known as ‘Distributed

applications’.

The technology of creating and running an

application in parts is also called ‘application

partitioning’.

CST Applications

A distributed application consists of a server

portion where most of the processing and storage

is performed.

This server portion is always executed and stored

on the server

This is also known as the ‘Back-End’.

CST Applications

The part of the application that runs on the client

and which provides the interface to the client is

known as the ‘front-end’

The front-end through its interface provides many

functionalities to the client.

The client can performs many important tasks

using this interface.

CST Applications

In the CST model, an application is split into a

front- end client component and a back-end

server component.

The front-end part of the application runs on a

workstation and receives data that is input by the

The client’s front-end prepares the data for the

server by preprocessing it in some fashion.

CST Applications

This processed information is then sent to the

server.

The data is sent to the server in form of some request.

The back-end server component receives the

client’s request and processes it and returns

information to the client.

The client receives the information and presents it

to the user

CST Applications

A good example of CST application is a web

application that is designed for Internet

Information Services(IIS).

Such applications are prepared by using

ASP(Active server pages) programming and client

side scripting.

The ASP program runs on the server and the client

side scripting runs on the client.

CST Applications

Basically a CST application has three main

components:

The front-end application

The back-end application

Network operating system

The Front-End & Back-End

In its general meaning, the term ‘Front-End’ refers

to the initial and the end stages of process flow.

These terms acquire more special meanings in particular areas

The general idea is that the front-end is

responsible for collecting input from user.

The input can be in a variety of formats but is

processed in such a way that it conforms to a

specification that the back-end can use.

The connection of the front-end to the back-end

is through the interface

In a s/w design, the front-end is the part of s/w

system that interacts directly with the user.

Front-End

Back-End

The back-end is the part which contains

components that processes the output for the

front- end.

The separation of the ‘front-end’ and ‘back-end’

is a kind of abstraction.

Abstraction helps to keep different parts of the

system separated

There are many example of front-end and the

back-end which are used in computer field.

Front-end is the part or the interface that helps a

user to interact with the machine.

For example:- Windows explorer can by defined as the front-end to the computer file system.

Similarly the GUI interface on the machines can

be defined as the front-end of the machine.

Most of the s/w packages have a front-end with

which user interacts and operates the s/w.

In complies the front-end translates a computer

programming source language into an

intermediate representation

And the back-end works with the internal

representation to produce code in a computer

language

The back-end usually produces machine

language code that runs faster

Similarly when we create s/w using dot net, dot

net works as the front-end.

Whereas the database where the data is stored Example:- SQL or Oracle is called the back-end.

Network Software

In order to define ‘Network s/w’ one must define

the individual terms ‘Network’ and ‘s/w’

A network is made up of two or more computers that are linked together.

Networks can be used for a variety of purposes

Generally networks are used to send information

from one computer to another computer.

Network Software

They are also used to play games or talk to a

friend or to combine computing power.

S/w can be defined as a program or a set of programs written to perform specific tasks.

So, using the definitions of network and software

we can define network s/w as follows:

Network Software

Network s/w makes it possible for computers to

communicate or connect to one another.

It can also be defined as the s/w which helps to send information from one computer to another.

The network s/w contains information about how

data is to be sent in packets to another

computer.

Network Software

Packet information includes the ‘header’ and the

‘trailer’

The header and the trailer contains information for the computer to which the information is being

This information includes address of the computer

to which the packet is sent, and how the

information is coded etc.

Network Software

Information is transferred b/w computers as either

electrical signals in wires, as light signal in fiber

optical cable or as electromagnetic waves.

Thus network s/w is the s/w which helps computers

in a network to communicate with each other.

They are also responsible for sending/exchanging

information b/w two computers

Some network s/w are Windows Server2003, Linux,

Window Server 2000, Novell Network etc.

Role of serverUNIT III

On the basis of Usage

1. FILE SERVER

2. COMPUTER SERVER

3. DATA SERVER

4. COMMUNICATION SERVER

5. APPLICATION SERVER

Manages workgroups applications & Data Files

Shared by the group and among the groups

File Servers are I/O oriented

Large amount of data Storage and data transfer

Space for storage is allocated and free space is managed by

the file server

Whenever data from a file is requested, a file server transmits

all records of a file and the entire index to the client

Requires many slots for network connection

It also needs a large storage capacity and fast

hard disk sub-system.

The main work of file server is to manage,

maintain and serve the file whenever a file is

requested.

2. Compute Server

Compute Server is used in a 3 Tier Architecture

Processing Server

CS passes client requests to a data server

Forwards the result

Processing on the client request.

Processing authenticity for security.

3. The Data Server

Data storage and management.

Conjunction of one or more computer servers

3. The Data Server

Processing is done by rule based procedures

Data validation, requires data management

function.

Multiple searches of data and frequent updates

of massive tables.

3. The Data Server

Task require fast processors

Large amount of memory and substantial hard

disk capacity.

Servers send relatively small amount of data

across the network.

4. The Communication

Server Communication Servers provide gateways to LAN’s, Network

System requirements with perhaps the greatest demands

being those for multiple slots and fast processors.

Powerful h/w to translate networking protocols.

5. Application Server

Application server is a machine that Server as a

Applications are downsized from a host, oneoption is to install the application on a smaller

machine that runs the same s/w & to hook all the

users to the new box

Process Requires no modifications to the based

app s/w

Host is server to GUI based clients

On the basics of SizeMICRO SERVER

SUPER SERVER

Micro Server :-

Performs all the functions which a Server needs

Micro Servers used the Intel 486 Chips to run at 33Mhz or

higher with 16 MB RAM.

Micro Server

Multiprocessing provided by certain O.S do not

provide multiprocessing

Example:- Novell’s Netware does not provide multitasking

Micro Servers use Intel 3.06GHz or Xeon or higher

processing speed chips with 1 to 4 GB RAM

OS support Symmetric multiprocessing

Micro Server

Latest Servers use Dual Core Technology having

64 Bit processing capabilities

Tremendous processing and executing powers

2. Super Server

Super Server is specifically designed for the CST

Provides certain hardware features

Multiple processors, large amounts of memory

High speed disk arrays

Specialized applications are used

Super Server

Higher configuration h/w & s/w

Advantage over a Micro Server

Increased Processing Power : multiple processors

Increased I/O capabilities :

Increased disk capacity :

Improved Memory Management :

Improved reliability :

Super Server

Improved maintainability :

Eg : Param (Pune, India)

ANURAG (India)

CLAY 1, CLAY 2 and CLAY 3, CRAY.

Features of Server

Server plays a very important role in the network

Speed and the Performance of a network

Server machine is a powerful machine

The general features possessed by a server are as follows :

Multi Processing

Multi Threading

Features

Disk Arrays

Disk Mirroring

Disk Duplexing

Parity Checking

RAID Components

1. Multi Processing

Multiple processors to increase processing speed

Workload is shared by the processors

Multiple processing can be further classified

1. Symmetric Multiprocessing

Dynamically assigned to any processor

Processing speed and resources are maximized

Capability supported by the Network Operating System(NOS) or

Server Operating System (SOS)

Application s/w should also support multiprocessing

Network

Services

File Systems

Engine

Disk I/O

Processo

r Processor

Processo

Processor

Symmetric

Multiprocessing

1. Multi Processing

2. Functional Multi Processing

Assigns a set of tasks to a processor

Multi processing also supports multi threading

Concurrent execution of multiple tasks

Network

Services

SystemPrint Disk I/O

Network

Services

Processo

Systems

Processor

Process

Disk I/O

Processo

Functional Multiprocessing

2. Multi Threading

Thread is smallest unit of execution

System can schedule it to run

A path of execution through a process

Thread consists of stack, an instruction pointer, a

priority, the CPU state and an entry in the system’s

scheduler list.

Thread may be blocked, scheduled to execute or

running.

2. Multi Threading

Thread communicate by sending messages to

each other and they compete for ownership of

various semaphores

The allocation of computing resources between

the individual threads

Thread asks the system for an instruction to carry

2. Multi Threading

If no instruction is ready, the thread is suspended

until it has something to do

If the instruction is ready, the thread performs the task and makes another request to the system for

3. Disk Array

Fault tolerant disk arrays, Redundant Array of

Inexpensive Disks(RAID)

Such Disks are standard on super servers

Disk Array’s usually include a file server and

software that controls access to the individual

drives.

RAID Redundant Array of Inexpensive Disks

Multiple drivers are treated as a single logical

drive by the server operating system

Transparently recover from the failure

The data is actually broken into chunks and

simultaneously written to multiple disks

If a disk fails, the data can be reconstructed by

reviewing the places of data

RAID currently has five levels of data protectionand error correction

1. Disk Mirroring

Disk Mirroring is the process of creating a mirror

duplicate of a disk

Such facilities are usually provided by the SOS

In this system two disks are attached to the same

disk controller

2. Disk Duplexing

Creating duplicate disk.

Individual controllers are provided for each disk

One of the disk is duplicated

3. Parity Checking

An extra bit is added to ensure that the

information is transmitted accurately

The extra added bit is called the ‘Parity Bit’

4. Redundant

Components

Redundant Server Components such as disk

driver. Power supplier an automatic supplier and

automatic recovery features are option on serversand standard on super servers.

Some super servers offer mirrored processors and

include remote alarms that immediately warn of

network trouble.

Network Operating

SystemNOVELL NETWARE

LAN MANAGER

Network Operating

System

Server Operating System is NOS

Operating system which is aware of a network

Additional features than a normal operating

system

Network Operating

System

These features include:

File and Printer Sharing

Data Security and Authentication

Distributed Applications

Messaging

Centralized Administration

Network Operating

System

Its main task is to receive and respond to user

requests for services

A NOS manages the services of a server

Various Network management tools

Run many other software

Generally an operating system manages the

resources of the server

Network Operating

System

Software to communicate with other computer

via a network

Manages multiple requests concurrently

Self contained operating system

Network Operating

System

For example:- Windows NT, UNIX

Remote drives on the server can be accessed

The server to handle requests from the client to

share file and applications as well as network

devices

Network Operating

System LAN’s which can either be peer to peer networks or CST

based.

Example:- NOS include Windows NT, Novell Netware and

Banyan VINES.

Cisco’s Internet Work Operating System (IOS) can be used as

OS on router

Network Operating

System

Peer-to-peer network, the NOS allows each

station to be Client & Server

Non peer to peer network, dedicated servers areused

File and print services a network OS include

directory services.

Messaging service as well as network

management and multi protocol routing

capabilities.

Network Operating System

NOS can be used for a variety of purposes.

The basic functions of a NOS are:

Authenticate user access

Share files and printers and exchange messages.

Network Operating

System

Centralizing administration of multiple computers

from a single management console.

Distributed applications that share processing onmultiple computers.

Network Operating

System

Some of the popular NOS are:

Microsoft Windows 2000/2003/2008/2012.

Novell NetWare

Various flavours of UNIX

Mac OS etc..

1. Novell NetWare

Novell that support DOS, Windows, OS/2 and

Macintosh clients

Network Operating System

Supports file and printer sharing, email, remote

access, inter LAN communication via a bridge or

a gateway

1. Novell NetWare

Controlling system resources and their uses.

Different versions

Version depends on type of services

Novell NetWare

The different versions of Novell Netware are :

Novell NetWare Lite

Novell NetWare 2.2

Novell NetWare 3.11

Novell NetWare 4.0

With each new version of Novell NetWare some

new additional features were added to it.

Novell NetWare

Some of the features include:

Increased number of clients can be connected

the server.

Better memory management.

Support for latest processor.

Support for increased RAM.

Support for Multiple protocols.

Novell NetWare

Better security options (Example:- Disk Mirroring,

disk duplexing or redundant components)

NetWare is used by organization, large and small

Provides common services

LAN Manager

Developed by IBM

LAN manager is NOS for networking

Different network OS according to characteristics

Requires that the server run OS/2

Clients use Macintosh or any OS

Works across multiple protocol

LAN Manager

Basic Features provided are:

Concept of Domain Name System.

Support for Multiprocessing.

Remote access service

Latest features a Server needs

Server Operating System

Introduction

Supports a large number of hardware

Provides multiuser multitasking OSE(Operating

System Environment)

Freely used on WS(Web Server), DNS(Domain

Name System), File Server(FS) etc…

Server side Application:

Apache Web Server

Samba Server

Samba enable a Linux Server to provide file and

print services to other platforms such as Windows

and Apple Macintosh.

OS/2 server platform, intel’s product

Provided by IBM in SAA(System Application

Architecture) model

Multitasking services

Network Operating System directly supported with

OS/2 are LAN Manager and LAN Server.

Combination of Novell with OS/2 DataBase And

Applications Server.

System Application

Architecture

SAA is IBM’s distributed environment

SAA define standards for CUA(Common User

Access), CPI(Common Programming Interfaces), Common Communication Link.

SAA framework is AD/Cycle

AD/Cycle designed to use third party tools

client server

ArchitectureUNIT IV

Concept & Components

of C/S

C/S architecture is based on framework

Consists of many PC’s, workstations & small

mainframe machines

Connected with communication media or

channel.

Tiered Architecture

Generally there are two types of nodes in a network.

One is Client and another is Server.

Two Tiered Architecture “the Client and the Server”.

Directly sends a response to the CS.

Direct communication between CS.

Main types of DBMS architecture:

1. Two tier Architecture

2. Three tier Architecture

Two Tiered Architecture

In a two tiered architecture there is no third party [machine ]

involved.

The server

2 Tiered Architecture

Client

Advantages of 2 Tier

Architecture

Easy to update data

Easy to upgrade and maintain such networks

Disadvantages of 2 tier

Architecture

Traffic jams in networking

Large number of clients sends requests and this

causes troubles for the server

More Clients more trouble

Server goes down and the Clients requests

cannot be fulfilled

Three Tiered Architecture

Networks consists of three different kinds of nodes:

Client : which requests data

Server : which processes data

Database Server : which stores data.

Such an architecture is called ‘ Three Tiered

Architecture’.

Google

Server

Facebook

Server

3 Tiered Architecture

Architecture

3-tier architecture one Server free to only

processing.

Server stores all the data only and does no needto do any processing.

Load/Burden is reduced on the Server.

Servers perform much better

Architecture

Better security control on data.

A Hacker has to pass through the processing

server to reach to the database

Disadvantages of 3 Tier

Architecture

Load on the network

Difficult to run or test a software

Communication Between

Client requests to the server for data or

information

Server is the machine which serves the data orinformation.

ORB are the middleware that enable Client &

Server programs to establish session with each

Client & Server can communicate, independent

of their location on the network or programming

interface

Process of Client invoking or call to an Application

Programming Interface(API)

Client issues the call, which is intercepted by the ORB

ORB takes call & is responsible for locating a server object

that is able to implement the request

ORB communicate among themselves using the General

Inter-ORB Protocol (GIOP) or Internet Inter-ORB Protocol(IIOP)

Any ORB can fulfil any Client request on the network

Use of API

Application Programming Interface let C and Assembly

language interact with services and programming tools

Window OS provides API to access standard operating system

and networking services and functions

Window OS provide predefined sets of API for various

purposes:-

(Telephony)TAPI for accessing voice, data of fax

(Messaging)MAPI for messaging functions

API call to the computer browser service

Middleware technology in

Three tier architecture

Intermediate layer between the client and

database server

Open System

Interconnection(OSI)

Intro:

OSI was developed by ISO(International

Organization for Standardization)

Model for universally accepted networking

protocols

Model describes how information moves

Conceptual model composed of 7 layers

Layer of

software

of OSI

Layer of

hardware

OSI Reference Model: 7 Layers

OSI Model19

1. Physical Layer

First layer of OSI model

‘Nut & Bolts’ layer

Physical interface b/w devices

Physical and electrical connection

Transmission media

Different protocols

2. Data Link Layer

2nd layer of the OSI model

Converts frames of data

Responsible:

Framing, Flow control, Error free Communication

Bridges and NIC work on this layer

Ensures that the data is transferred reliably

Responsible for addressing, Frame sequencing, error

detection and recovery

Data Link Layer

Layer deals with getting data packets on and off

the wire

Error Detection, Correction and Retransmission

Layer is divided into two layers

LLC – Logical Link Control

MAC – Media Access Control

PacketData

Trailer

Header

CRC(Cyclic Redundancy

Check)

Source MAC Address

Destination MAC

Address

A cyclic redundancy check (CRC) is an error-detecting

code commonly used in digital networks and storage devices to

detect accidental changes to raw data.

3. Network Layer

Addressing and routing of packets

Establishing and releasing connections

Transferring data, Generating and confirming

receipts and resetting connections

Packets sent from one device to another

Routing and flow control are formed here

Packets

SegmentNetwork

Header

Source IP Address

Destination IP Address

4. Transport Layer

The Heart of the OSI model

Responsible for providing reliable transport services to Upper

Flow control

Multiplexing for combining data from several sources

Layer uses TCP/IP protocol

Port is a Logical Communication Channel

Segment

DataTransport

Header

Source Port No

Destination Port

Protocol No

Sequence No

It provides data

delivery

mechanism b/w

the application in

the network

sequencing

5. Session Layer

Responsible for:

Establishing and Terminating a session in a network

Synchronizing data exchange b/w 2 computers

NetBIOS protocol works at this layer

Sessions ID’s

Examples:

RPC – Remote Procedural Call

SQL – Structured Query Language

ASP – AppleTalk Session Protocol

6. Presentation Layer

Presentation layer is responsible for

1 Data Translation

2 Data Compression

3 Data Encryption.

Interpretation of graphics

commands

E.g.: ASCII, MIDI, WAV, MP3 etc.

6.1. Data Translation

Application layer will need to convert data

Receiving format understood and accepted

OSI model to ensure smooth file transfer

Data formats include postscript, American Standard Code for

Information Interchange (ASCII), or BINARY such as Extended Binary Coded Decimal Interchange Code (EBCDIC)

6.2. Data Compress

The goal of data compression is to represent an

information source (a data file, an image) as

accurately as possible using the fewest number of bits

For example, 25.888888888

This string can be compressed as:

25.[9]8

Interpreted as, "twenty five point 9 eights", the

original string is perfectly recreated, just written in

a smaller form

6.3. Data Encryption.

Process of transforming information (plaintext)

Using an algorithm (called cipher) to make it

unreadable to anyone except those possessing special knowledge

Usually referred to as a key.

Result of the process is encrypted information

(referred to as cipher text).

7. Application layer

Window b/w user and other

networking services

Runs the s/w with which the user

interacts

FTP and HTTP protocols are used

Layer acts as an interface b/w user

and network

7. Application layer Protocols

HTTP – Hyper Text Transfer Protocol

FTP – File Transfer Protocol

POP – Post Office Protocol

SMTP – Simple Mail Transfer Protocol

SSL – Secure Socket Layer

Telnet – for remote computer access

IPC (Inter Process

Communication)

Allows one process to communicate with another

process

Processes run on same computer or on different computers which are connected through a

network

IPC techniques are divided into methods

Message passing, Synchronization, shared

memory and Remote Procedure Calls(RPC)

Client Server Computing written by Munesh Trivedi

Or Mamta Rani

The Essential Client/Server survival Guide written

by Robert Orfali , Dan Harkey Or Jeri Edwards

Unit V

C/s system

development

Network Management

Network means connecting two or more

computers in such a way that they are able to

share data & h/w

Networks can by very small or very large

Every type of network faces problems regularly

Problems need to be solved regularly for easy &

good performance of the network

Network Management

Network can face the following problems:-

1. No connection

2. Wrong or no user accounts

3. Faulty or loose wires

4. Domain name problems

5. Server down

6. H/w problems (switch, router)

Network Management

7. No services available

8. Wrong or invalid permissions

9. Server OS problems

Network has to be managed regularly

“Network Administrator”

Five key OSI management areas

Fault management

Performance management

Inventory management

Accounting management

Configuration management

Security management

Remote System

Administrator

Able to create very large network

C/S machine very far form each other

Access files or folders

Install or uninstall any s/w, format, restart

Save time & money

Facility provided by the OS

Remote System

Administrator

Remote administrator can also be very

dangerous

Unauthorized user can easily Access

Hacking

Difficult to catch such user

LAN Management

Limited area

in a campus

Regular problems

Management is also compulsory

Same Network management

The responsibility of network administrator or LAN

administrator that the entire network will not be

crashed or failed.

The data or information will never be lost on any

LAN network management there are certain issues or services

Network Maintenance

Network Integration

Capacity Planning

Equipment Maintenance

Security Administration

Network Cabling & Installation

Network Application & Administration

Server & PC Data Backup

1. Network Maintenance

The computer are connected with each other

The structure & layers what type of connections

are used for better network

We can use routers at some places, hubs,

switches

Facilities of disk mirroring, disk duplexing

There is less possibility of network failures

We can maintain the network & make it work

efficiently & effectively

2. Network Integration

Network Integrity mean that all the systems should

work & function Homogenously

System should have a contact with the Server

Developing Application

On RDBMS

S/w used to store large amount of data

Processes data & provide information to user

Technical users use SQL & RDBMS

Developing Application

On RDBMS

Designed in s/w like VB6 or VB.net

Screen fully graphical, friendly & easy to use

Screens acts as “FRONT-END”

RDBMS acts as “BACK-END”

Used in Banks, Railways, govt. offices etc…

GUI Design Concepts

Gives controls to work in GUI

Help to work easily & fast

Controls include textbox, radio button etc…

Important role in designing graphical screens

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