E-LEARNING CONCEPT

 OBJECTIVE:-

Education is essential now a days and to do this we have to learn various things .We are learning through various site if the mode is ONLINE so the ONLINE learning is essential now a days .We are following various model in which we can deliver our learning session to the readers .The main objective of this unit to understand the details about models and and how this method is made effective and flexible.

What is E-Learning?

Basically what a trainer is delivered all this will come to reader or learner through electronic form.Any institution want to share its materials that is also in electronic form and all this are done in one platform that is web.Now if combined the above we should understand the exact definition i.e 

Any materials related to any field whether it is training material,any subject notes or any education related information which is delivered through web electronically is known as E-Learning.

ON-LINE course is one type of example of E-Learning which is very popular now a days Learners are not only get the subject related  materials but also access those materials in form of audio and video 

Why E-learning?

Today's competitive world learning is endless.Now take an example suppose an organization having thousands of employees ,technology is upgraded day by day and  for this an employee need to be upgraded regular interval. Each time organization is not able to conduct training where all the employee located different location need to come to attend a particular training center it makes it more costly.

E-Learning provide affordable training which is flexible and cost effective.An employee can get his training from his home though he may located so far no need to travel and within short period of time trainer can deliver his training session .It also able to generate reports as because various tools are available which generates the reports of student progress and can also tracks budget of the training.

ADVANTAGES

1.It is cost saving.The development cost ,maintenance cost is less.

2.It helps to give the update of any topic to any learner instantly over Internet or Intranet.

3. Through on line unlimited no of colorful graphics can be delivered.

4.Any learner can get instant answer if he face any subject related difficulties.

5.It also generates various reports. student or teacher or learner  easily understand how they are progressing and their feedback also.

FUNCTIONAL MODEL E-LEARNING

To understand functional model we have to understand two main important terms 

1.LCMS(Learning Content Management System)

2.LMS(Learning Management System)

LCMS(Learning Content Management System)

It is developer side ,a developer can create the learning content ,decide where to store ,how to reuse,how to manage,and how to deliver this content to multiple user.It is actually focused on course delivery .

Any learning course if you see you will find different tools are used in learning course like word,power point,video,audio LCMS combined all this tools into single system then arrange it in proper way and give the structure to crate and deliver courses to multi-user.Multiple developers or expert share their subject matter or learning content and all of this are controlled by LCMS.

Suppose a learner is searching a content LCMS provide the related content to the learner from content resources and managing all this in well formed manner.LCMS renders the respective content which a learner is looking for and also track learners progress ,bookmark,progress,test scores etc.

LMS(Learning Management System)

LMS manages the processes surrounding learning .It is helping an organization for running and LCMS gets the right content  to the right people at the right time both are helping each other though both are different in concept.

LMS makes the process of scheduling classes,it also helping to create catalogs and registering learners more efficient way. LMS manages user and communities like registration ,assignment etc.

To create Learner progress report some data is needed like learners test scores that data is collected from LCMS and forwarded to the LMS and LMS collect all the data and generate progress report.

E-LEARNING STANDARDS

E-Learning standards concept came into the technical field when we are thinking about multiple user accessing learning content from multiple platform .The ON-LINE courses structured like such that it can be operated by different platform so E-Learning standards is nothing but a system which follows a common rule that enable ON-LINE courses can be created  from multiple platforms and also courses can be delivered over multiple platforms .

An standard if approved by stamps from an accrediting body and its specification is signed by an accredited body like IEEE(Institute of Electrical and Electronics Engineers) it is known as de jure tandard.

Another standards known as de facto standard which is exist and adopted by mass people but officially approved .Like HTML accepted by web developers but not officially approved by an accredited body .However most of the E-learning standard fall under de facto standard.

The E-Learning standards are being adopted by four main organization

1.AICC(Aviation Industry CBT Committee)

2.IEEE(Institute of Electrical and Electronics Engineers)

3.IMS(Instructional Management Systems)

4.ADL(Advanced Distributed Learning)

The most widely accepted under ADL standard is SCORM(Shareable Content Object Reference Model.It enables web related learning and content management systems to find,reuse,share,import and export learning content in consistent manner 

OBJECTIVE OF SCORM

1.Accessibility:-It can be accessed from remote location also and can b delivered other locations

2.Adaptability:-Content manager can able to add new content easily.

3.Affordability:It is reducing the time and cost also

4.Durability:-It is durable in the sense that regardless of change or up-gradation of new technology new content can be added without reconfiguration or without costly redesign.

5.Reusability:Content developers can access different modules from different course can combined them into new course.

CHECK YOUR PROGRESS

What is E-Learning?

Why we used E-learning?

What are the advantages of E-Learning?

What is functional Model of E-Learning?

What is LCMS(Learning Content Management System)?

What is LMS(Learning Management System)?

Difference between LCMS and LMS

What is SCORM ?

What are the advantages of SCORM ?

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COMPUTER HARDWARE AND INPUT OUTPUT DEVICES

 OBJECTIVE

In this topic we would learn various computer parts which are related to computer hardware  and we would also learn the details of computer hardware and their main function.We would learn various input and output devices    

HARDWARE

Computer hardware is very useful components which we can see and tangible means we can able to touch such components.Computer hardware having three categories:storage,input, and output.

CPU

Central processing unit  is the brain of computer.It stores large amount of data.It is main controller which control the operation of all parts of computer

Central processing unit consists of three units 

1.Memory or storage unit

2.Control unit 

3.ALU (Arithmetic Logic Unit)

                                                   

                                1. MEMORY

The data entered by users are stored in Memory or Storage unit.

The two main types of storage devices are  memory and disk drives .Computer memory also classified

into two category

                             1.Primary Memory

                             2.Secondary Memory

Primary Memory

Primary Memory or Main memory is computer memory which can be accessed by the CPU .It is more expensive.It holds the data or the instructions which the processor currently working on .Primary memory devices are semiconductor memories

Primary memory further classified on two parts

                                                                           1.RAM(Random Access Memory)

                                                                           2.ROM(Read only Memory)

1.RAM 

It stored the data short term basis as soon as power of the computer turned off it lost all the data so it is called volatile Memory.Data is temporary stored

It also further divided into mainly three parts

a)Static RAM (SRAM)

b)Dynamic RAM (DRAM)

c)Synchronous Dynamic RAM (SDRAM)

2.ROM

ROM is non-volatile memory because data is permanently stored which means when power of the computer turned off data is not lost so it is called Non volatile Memory

It also further divided into mainly Four parts

a)MROM (Masked ROM) 

b)PROM (Programmable Read Only Memory)

c)EPROM (Erasable and Programmable Read Only Memory)

d)EEPROM (Electrically Erasable and Programmable Read Only Memory

Secondary Memory

The Processor does not communicate with  secondary memory directly so data which are stored in secondary Memory  transferred to the primary memory which are then  accessed by the processor.Secondary memory devices are less expensive as compared to primary memory devices.Secondary memory is also known as External memory or Auxiliary memory.Secondary memory devices are magnetic and optical memories.

 Hard disk Drive : It  can store large amounts of information.The disks are of different sizes such as 1G, 10G, 40G, etc.Hard disks are flat, circular plates .It is an electro-mechanical data storage device .

Floppy Disk Drive: It stores less information than hard disk and access speed is also slow.

Now a days very few computer we are using it.

Compact Disk Drive:Compact Disk Drive is used  to access the compact disk (CD) but its having slow speed than hard disk in  terms of data accessing but can store more data than Hard Disk.In  a CD there is a hole at the center which is known as manual eject hole or it is also known as Emergency eject hole .There are three main types of CD this are

Standard manufactured CDs (CD-DA), 

CD-R recordable and 

CD-RW rewriteable

DVD:DVD stands for Digital Versatile Disk.The storage is much more CD .Compact disk can hold around 700MB data where as DVD can store 5GB data.In case of CD the metal layer or recording layer located top of the disk where as in  DVD the metal layer or recording layer located middle of the disk.

FLASH DRIVE :In the flash drive the memory is called flash memory which is nothing but a type of computer chip.It has more memory than floppy disk but can store less data than hard drive.It is very fast compared to CD and DVD.It is light in weight.It is using less power than hard disk drive.

MEMORY CARDS:Memory cards are electronic device which can tore electronic data like photos,movies, games,music, documents, programs and  many more.It works like flash drive but it having additional device known as card reader.It is durable and very effective than flash drive.

                                2.CONTROL UNIT

It i mainly responsible for controlling the data transfer and instructions among the other units.It communicate with input output devices.It does not process any data.It is mainly controlling all the other parts of computer.

                                   3.ALU

Arithmetic Logic Unit(ALU) having two section

1.Arithmetic section which is responsible for arithmetic operation like      addition,subtraction,multiplication,division.

2.Logic section :This section perform logical operation like comparing,selecting,matching etc.

INPUT DEVICES

1.KEYBOARD:-It is the input device through which we can type text .It is having around 104 keys.NUMBER KEYS(0-9),LETTER KEYS(A-Z),SPECIAL KEY (SPACE BAR KEY,ENTER KEY,CAPS LOCK KEY,DELETE KEY etc

2.MOUSE :-It is known as pointing devices.It helps to point different things on the computer ,draw and color and play games.It has two buttons and one wheel in center.

3.JOYSTICK:It is used to play computer games.

4.SCANNER:It copies the pictures and text from paper onto the paper.we are commonly used desktop flatbed scanner

5.LIGHT PEN:A light pen is light sensitive input device which can be used as a locator,as stroke input devices .

6.MICROPHONE:-Microphone is an input device which converts sound into signal which is stored into the computer and played back by computer

OUTPUT DEVICES

1.MONITOR : -It is the main part of computer output device looks like television also know as Visual Display Unit (VDU).Its having different sizes.Mainly three types of computer monitor are 

1.Cathode Ray Tube(CRT)

2.Liquid Crystal Display(LCD)

3.LED(Light Emitting Diode)

2.PRINTER: A printer is used to print information that you see on the monitor on to the paper.The printed paper is known a hard copy or printout which can be touchable .The information on the computer is called soft copy which is not touchable.

3.PLOTTER:-A Plotters are  automated pen,pencil or marker which is used in specialized fields such as drawing, architecture and engineering. It also  can create designs such as diagrams, blueprints etc.There are two main types of plotters drum(roller) and flatbed plotters.

BUS

 Bus is communication path between two components it can be memory to input output devices ,it can be processor to input output devices.It is same like one passenger moving from one place to another the mode of communication is vehicle this may be BUS(Vehicle) same concept in computer system also.If i want to transfer data from one component to another component i can made it through bus. 

If you see the diagram you can see in the center M denotes Memory Connecting with various component diagram it is denotes as C and all this connection is made through communication Bus called BUS

Bus can be classified as 

1.Address Bus

2.Data Bus

3.Control Bus

ADDRESS BUS

It carries memory addresses from the processor to other components such as input /output devices,primary storage. etc.

Address Bus is unidirectional means data is flow only one direction.Microprocessor to memory or from memory to input output devices.It is unidirectional because outside device not able to write into microprocessor

DATA BUS

It carries data between the processor and other components.It is bidirectional because data can flow both direction from Memory to  input /output devices and from input /output devices to Memory .

CONTROL BUS

Control Bus carries signal from the processor to other components.Control bus carries signal where data need to be transferred at sending time it carries the signal and giving alert to the components i am sending data are you ready?  After receiving  the data by the component it will sen signal to the memory an conforming yes i am received the data so signal is transmitting both ways it is  bidirectional .

So remember that only Address Bus is unidirectional and Data Bus and Control Bus is bidirectional.

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NETWORKING SYSTEM (DATA COMMUNICATION SYSTEM)

 OBJECTIVE

The objective of this topic to understand networks of  Local and wide area communication.This topic will help to understand network connectivity issue of any organization.Various types of data communication and how this will work this is covered in this topic.

DATA COMMUNICATION 

Data may be sent for short distances or for long distances also .In case of short distances digital data can be sent direct over direct wire digital link it may be through simple copper conductors.In case of long distances we used digitally modulated analog carrier signals.

ELECTRONIC MAIL

In such communication we can transfer data in form of text from one place to another .Each user having a mail box in which the message are stored which are sent by sender and from mail box we can access the messages.

An email data communication system consists of 

1.Source computer and destination computer                                                                                               

2.Modems which is data communication devices\

3.Cable which works like a communication channel

4.Data communication Software

DIAL-UP LINES

In this data communication two computer systems use dial up lines connected by modems and using telephone network.It is the simple method .we can connect two remote computer easily.In case of  Dial-up lines the charges or cost depend on distance between two user and time spent or how long connection is made.It is the cheapest transfer medium.

LEASED LINE

It is dedicated data communication where dedicated link established between the source user and destination user.It is high performance data communication because leased line is permanently allocated by telephone network.In leased line cost is fixed i.e same rate is charged whether you used communication facility or not.

INTERNET CONNECTIVITY

The connection can be either wired or wireless.The wired connections use PSTN(Public switched telephone network) /PSDN(Public switched data network.The wireless connection in wide concept using satellite communication.Many internet service provider provides internet servers like GIAS(Gateway Internet Access Service) of TATA Communication,NICNET(National Informatics Centre Network) .The user get connected with internet through Internet Server

There are mainly two ways of connection methods

a) On-Line Connectivity

b)Off-Line connectivity

INTRANET

Intranet and Internet are two different things.Intranet is nothing but an application of the internet technology to a closed network where every user is not allowed to connect with Intranet.Intranet uses Internet-derived communication protocols(TCP/IP),IP network and a user interface like Web browser .Protocol is nothing but set of rules which helps electronic devices to communicate with each other.

It i used for corporate application.

LAN

In LAN(Local area network) more than one computers connected together typically a single building,office,home and communicate with each other and also share computing devices like file servers,printers,scanners etc.This are called node and this nodes are connected with LAN through Interface Hardware called adapter

The network consists of shared transmission medium having data rate 100Mbps or 10Gbps.

Many different types of media are used for LAN

1.Guided Media

  In this media the transmitting signal follow a narrow path and will behave predictably.The three most commonly used media are Twisted-Pair wiring ,coaxial cable and optical fiber cable.

2.Unguided Media

It can be used as physical paths to carry electrical signals.The atmosphere and outer space are example of unguided  media which can carry microwave infrared light waves and radio waves.

HUB

It acts as a central point for LAN cable.Repeater is the example of hub which simply connect cables together and regenerate data thereby passing  data from one device to another.There are also hub which connect network segments and routers ,which connect different types of both local and wide area networks.This types of hubs are specialized and related to the network they are used in.They are typically installed in very large and complex networks.

BRIDGE

In a network if more devices are connected  more collision will happen and therefore the avg throughput will go down so as a solution if we divide the network into separate networks or segments and within each segment device will continue to communicate with each other then throughput remain same and to do this a device  called bridge is often installed that connects to these network.

SOFTWARE

Software is required by the network to operate which is Known as NOS(Network Operating System).NOS support peer to peer architecture and also support Client/Server architecture.Device drivers program is required for adapters installed in LAN.

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DATABASE MANAGEMENT SYSTEMS (DBMS) CONCEPT

 

Definition:-A database management system (DBMS) consists of collection of  data which are interrelated with each other and a set of programs used to access those data.

It is collection of data about one particular enterprise and it is designed to mange large information and creating an environment where we can retrieve and store database information.Data which is stored in database should be safe .This safety is managed by data base system.

Earlier one concept was there known as file processing.Its having various disadvantage which is solved in database management systems

DISADVANTAGE OF FILE PROCESSING:-

1.DATA REDUNDANCY AND INCONSISTENCY

In file processing same data is stored in different locations which leads data redundancy for this large storage area is required which increase the cost.Data redundancy means duplicate data stored in different location. 

Now suppose you want to modify any data in case of file processing modification is very difficult  because data may not modified at all the places in same time so this create huge problem which is known  as inconsistency.

2.SECURITY PROBLEM

In file processing security is the main problem as data can be accessed by all users and modified by all users.In case of database system all the users are not applicable to access or modify the data. In case of database system users are classified based upon the different  accessibility of  different  users .Higher level user or administrator accessibility is different from lower level user or normal user.

3.DIFFICULT TO ACCESS DATA

In File processing needed data is not retrieved in convenient and efficient manner which is not in the case  of database system.

4.DATA ISOLATION

In case of file processing data is stored in different location and different formats so it is difficult to develop any program to access the stored data  from different location ,in one words data is not isolated and in case of database data is isolated properly.

5.INTEGRITY PROBLEM

In case of file processing same data is stored in different location so to integrate the data developers are facing problem which is not in the case of database management system.

6. ATOMICITY PROBLEM  

In any transaction suppose in case of ATM transaction a customer want to withdraw money  here two conditions are there either customer gets money means successful transaction or not get the money due to system failure called unsuccessful transaction.A transaction is set of commands should be completely applied or not applied at all .This is called atomic.It is the main criteria for money exchange.It is difficult to ensure this property in file processing .

7.CONCURRENCY PROBLEM 

In any application multiple user access the data and updates the same data simultaneously.There is a chance of inconsistent data updation so to overcome it some mechanism introduced in database system called concurrency control which mechanism not present in case of file processing.

Database management system overcome all the drawbacks of file processing system.

DATA  INDEPENDENCE              

 Why we need database system ? 

A major purpose is to abstract the view of data for end user means data are hides from the end users and how the data are stored and how the data maintained all this are hided in case of database management system.

In database system data  which are stored should be maintained such that it should be retrieved efficiently ,design may be complex for this but user are not aware of it that is the user is unknown about the background of database system  which is nothing but mechanism,complexity ,stored procedure,and maintenance all this is totally hidden for end user this is data abstraction.

In Database system three levels are followed 

1.Physical Level

It is the lowest level of data abstraction

It describe how data are actually stored .

Database administrators only aware of the certain details of the data.

2.Logical Level                                                                                      

It is the next higher level after physical level.

It abstract what data are stored.

It also abstract the relationship among those data.

3.View level

It is the highest level of data abstraction .

It describes only part of entire database.

In a large application data are extracted from  more than one file but user is unknown about this information .

DATA MODELS

Data model is nothing but collection of tool which describe data ,data relationship,data semantics and consistency.

Entity relationship model

An entity is nothing but collection of  objects and entity relationship means relationships among these objects.Entities are set of attributes which are described form.A relationship is an association among different entities.

Relational model 

It is collection of tables to represent both data and the relationship among those data.Each tables having multiple columns and all the columns having unique name

 

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PROGRAM ,TYPES OF PROGRAMMING LANGUAGE,SOFTWARE

 A program is nothing but some set of instructions which is executed by computer .It is perform specific task which runs through computer operating system.All the instructions are ordered form.All the instructions are run one by one.Computers are useless without program.

Suppose you want to cook something for this you need some spices ,oil,salt etc but to prepare it you need to follow the rules that means when you have to add to oil when you have to add the salt,when you need to add various spices one by one otherwise your food will be not prepared properly.Some instructions you need to follow and should be executed accordingly. Program is just like recipe which is executed by computer sequentially.

The program is stored in a place called storage area also known as memory.

The program give the instructions to the computer and one who write the program is called programmer.

The programmer giving the instructions are called program.Now the question is that in what language the programmer can write so that computer can understand the instruction and will give the output for this a language is needed that can be understand by computer it is called programming language

TYPES OF PROGRAMMING LANGUAGE

 Machine Language

Computer can only understand binary form (0,1) Machine language is direct binary form a combination of 0 and 1 which computer can understand easily but to write this program you need to know the architecture of computer properly which is very difficult and all the computer not following same architecture.Machine language is very difficult .It is machine readable.It is very difficult to learn for this you need to know details about computer processor ,architecture and you need to know every thing for this which is really difficult .If any error is occurred in this language then it is also difficult to find out.For each and every architecture of a computer  you need to write different language.No symbolic code or numeric code is used in this language

Assembly Language

Assembly program is readable by machine as well as human also.It is much easier than machine level language in which numeric and symbolic code can be used .

ADD 2 ,ADD 6, is used for ADDITION 

SUB 3 is used for SUBTRACTION 

So  it is little easy for programmer to write the program.Now the problem is that how this program can be executed through computer because the computer only knows binary so i need to convert it to binary form .An assembler convert this source code and transfer it to in binary form helping computer to understand and for execution.It is easy with compare to machine level language but its having difficulty in the sense that the length of the program is large and if any error is occur in between finding out the error and rectify it is main drawback of this language.

Assembly and machine language basically low level languages. 

Abstraction means hiding the complexity from the end user .Low level language having less abstraction.It is relatively non portable.

HIGHER LEVEL LANGUAGE

Higher level language is much more easier to learn and write .Program length is not so long and easily rectified if error is occurred.It is human readable but again this is not readable by computer because computer understand binary language so this high level language need to be convert to machine level language.

Compiler and Interpreter doing this function which convert high level language to the binary language .

Compiler:-It scans the whole program and translates into machine code so error is not checked line by line .It is taking much more time to analyze but taking less time for execution.

Interpreter:It checks line by line ,execute line by line .It is taking less time to analyze but taking more time for execution. 

High level languages having high abstractions. All the functionalities  is hided from the end user.It is portable.

SOFTWARE

Software means nothing but a set of programs ,procedures,documentation which executed by computer and perform productive task for user.It is used to operate system computer hardware and used to perform specific task.

Computer software can be divided into three categories

1.SYSTEM SOFTWARE

When we installed any operating system one software automatic loaded in the system which helps to run the computer hardware which is nothing but system software.

It is working inside the system and communicating with system hardware so no user interaction is occurred and running independently in the background. It is very fast and secure and is used for general purpose.

Low level languages are used in system software.It is not interactive  and difficult to design.

When you switch on the computer system the system software starts and stops when you shut down the computer system. 

It actually manages the resources like memory

Examples:-Operating system software ,communication software etc.

2.APPLICATION SOFTWARE

It is depend on user requirements.Users are interacting with application software.It is dependent on system software without system software application software will not able to run .It is used to perform productive task for the user.High level language is used in application software.It is very easy to design and very interactive for user.It is specific purpose software .How long it will run totally depend on user .Starts and stops are in users hand.

Example:Business software,education software,web browser,medical software etc.

3.PROGRAMMING SOFTWARE

Programmer are one who writes the program and to write the program some tools are required .Programming software provide such tools (text editors,compilers,interpreters)to support the programmer  to write program using different languages.

IDE(Integrated Development Environment)-It merges essential tools into a software package and with the help of this programmer need not to type many commands for debugging ,tracing,compiling,interpreter etc because IDE has an advanced graphical user interface(GUI).

Example:-Notepad++(editor for windows),Coda(programming language editor for MAC)

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CLUSTER COMPUTING

CLUSTER COMPUTING 

Cluster computing means a group of computers,node or data points are interconnected and appears as single system.It is applicable for server also where group of servers are connected and working together which Is known as server clustering. 

In Cluster Computing Complex and larger task is divided into small tasks. 

Clusters has been used for 1980s Sun micro systems,Microsoft and many leading software and hardware companies offering clustering packages which offers scalability as well as availability. 

CHARACTERISTICS 

         1.All the nodes having the same operating system and same hardware so it is                            basically homogeneous network. 

        2.All the nodes need to be located in a single location .

        3.All the devices are connected through local area network (LAN) 

       4.One manager manages all the thing called centralized manager 

           which manages the resources. 

       

       5.It follows distributed and parallel processing where more than one 

          processors execute multiple task simultaneously so It is multitasking. 

 

       6.It is high availability and load balancing. 

       7.All the nodes doing the same job or task or operation no other task is allowed. 

       8.All the nodes are tightly coupled. 

       

       9.The quality of cluster is measured through its performance and how it find out the                   hidden pattern

       10.High availability which means if one node gets failed the other nodes will be proxy

            for the failed node 

       11.The software used in cluster computing is called Clustering middleware.

   

       12.It is followed Message Passing Interface and flexible PVM(Parallel Virtual                             Machine) message passing system for mode of communication.

       13.It is deployed in Cloud computing environment also.  

Types of Clustering

 

Clustering divided into different categories based upon various criteria 

               Hard Clustering: A given data point or node belongs to one cluster. 

               Soft Clustering:-A given data point or node belongs to more than one cluster.  

           Hierarchical:-Which follow top down or bottom up approach.

               Flat Clustering: No hierarchy is present and it is very simple. 

               Model based Clustering : Here data is modeled using a standard statistical                                                                       model. 

              Open Clustering :-Here all the computers or data point having IP address which                                                 are accessed by Internet .

              

              Closed Clustering:-The data points or node are behind the gateway which is                                                         highly protected.

APPLICTION

 It is basically used for load balancing.It is applicable for those website where traffics are more.

Manager server is managed all the process.When end user searching for a particular webpage this request is directly sent to manager server then the manager server sent this request to similar kind of servers to fetch the data and sent it to end user.

Cluster computing also used in very low cost form of parallel processing for scientific purpose also.It is mainly used for computational purpose.

It is used for many web application such as web server,search engine,email and proxy server. 

It is used for image processing also.

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CENTRALIZED AND DISTRIBUTED DATA PROCESSING

  Centralized data processing means the various tasks or jobs coming from different dump terminal are collected and processed by single computer which is located at the center.The central processor having high power speed because the data need to be collected from dump  terminal should be responded within short period of time.It means waiting time should be less and for this speed need to be high.Dump terminal is the terminal through which the user giving input and gets the output immediately 

The user give input to the dump terminal then it is sent to the central processor, the central processor process the data and sent back to the terminal and user get the immediate response so terminals are many but it is processed by one centralized processor only.Inputs are  coming from many terminal  to one server and when data is processed it is sent to many terminals so output flow is one  server to many terminal.Centralized processor having huge workload for this and to do so each job is allocated by  time slice so time need to be shared between the jobs this is called time sharing and such kind of system is known as time sharing system.Now it's having one problem that if central processor is failed anyway then the terminal will not get the response. All the jobs immediately suspended and user also will not get the response that is the biggest disadvantage of such systems.

DISTRIBUTED DATA PROCESSING:-To understand this we need to know the concept of decentralization.In centralized processing work load is not distributed central processor or server is handling the workload alone if main server failed somehow the total system is failed, to overcome this the workload is need to be shared  and in decentralization the work load is shared by more than one server.In centralization processing one single authority controlling the data but in decentralization processing many authority having the power to control the data and process the data.The decentralization was actually followed by a concept called distributed processing here computers are connected together by  communication network so in this technique each computer can able to handle its own work load  and take its own decision.

Now from the diagram we can see that  three no of server named A,B,C are connected with each other  and each server connected with so many computer here it is shown as rounded dot circle .Work load is shared by three server and suppose one server is failed say C it will not create problem for other two A,B so whole systems will not fail at all.A distributed data processing system having the advantages of both centralized and decentralized system.A computer of one location can exchange data to the computer located at remote area and also processing the jobs to other computers at distant locations.

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ON LINE PROCESSING

 

ON-LINE PROCESSING

The word on-line processing means we get immediate response from the system as soon as input is given to the system or we can say waiting period is less to get the output.

It is different from batch processing where master file is not updated immediately like interest calculation of bank accounts where the response from the server is not required immediately it can be done once at the end of the day .

Now think about another application i.e. Railway  booking as soon as ticket reserved by anyone  then and then server need to be updated because if it is not done we get wrong information from the system. suppose booking a particular train ,100 tickets are available if 5 ticket is booked by a person now available ticket is 100-5=95 right now think for this particular application whether batch processing is perfect or we should apply on-line processing of course we should go for on-line processing as because we need to update the server immediately as soon as ticket booked by a person.

The system through which on-line transaction is processed is called on-line transaction processing (OLTP) systems.

Now suppose  5 persons from 5 different places trying to book the ticket of the same train at same time then what happened master file need to be updated at the same time but  if this occurred  we get wrong data or record from the server here we can apply the concept of record locking.

In this process the record need to be locked when the record which is currently used  so that no one can able to update it at the same time.

Out of 5 user when the 1^st user use the the data ,record updation is locked for other 4 user as soon as 1^st user finishes his job other 4 users which is on queue the record is freed or unlocked for them so record locking is the main feature of on-line processing.

Now suppose the system is fail somehow now how we can know which transaction is successful and which are not here another concept is coming i.e Checkpointing which keep track of master file each and every time before and after updation.

Checkpointing helps user to restore its original position before updation or it can re-apply updation to an earlier copy.

Now if I want to track which transactions were actually applied or successful it can be done through a process named Logging which actually tracking the transactions.

· In On-Line processing each item having transaction code.

· In batch processing data is sorted but in on-line processing without sorting the transaction data it is directly fed in the secondary storage device under CPU control

·  All the data is valid or not that is checked through validation process.

· All validate data is stored on secondary storage device.

· All validated data then processed through and updated immediately in master file.

 

ON-Line Enquiries

If the user having any enquiry and need immediate information then on-line systems are used.

Some special enquiry program is used in such systems where transactions need not to be upated only enquiry is needed.

Lets take an example if I want to enquire my PNR STATUS or Bank account balance no need to update the master file as because this is enquiry only.Each enquiry having some enquiry code if user makes any enquiry the system runs the respective program based on the enquiry code .The information will be shown on the display screen or the information also coming printed form.

 Like in ATM if account holder want to know the balance then the output means balance coming on the ATM screen as well as we get balance in printed form.

Such systems use a special written programs called macros which is use to perform repetitive tasks .

It was used before but now we are using upgraded technique SQL(STRUCTURED QUERY LANGUAGE) which is more flexible than macros.

Remember On-line enquiry system does not do online transaction processing.

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