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Introduction to Information

System Development

Unit 1

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System Analysis and Design In business, System Analysis and Design refers to the

process of examining a business situation with the intent ofimproving it through better procedures and methods.

System development having two major components:

System analysis System design.

System design is the process of planning a new businesssystem or one to replace or complement an existing system.

System analysis is the process of gathering and interpreting

facts, diagnosing problems, and using the information torecommend improvements to the system.

Example of Stockroom operation of clothing store.

Analysis specifies what the system should do. Design states

how to accomplish the objective.

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What System analysis is not

It is not: studying a business to see which existingprocess should be handled by computer and which

should be done by noncomputerized methods.

It is not: Determining what changes should be made.

It is not: Determining how best to solve an information

system problem.

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Systems Analysts' work Role of System Analyst differs from organization to

organization. Most common responsibilities of SystemAnalyst are following System analysis only (Information analyst): It includes

system's study in order to get facts about business activity. It is

about getting information and determining requirements. Herethe responsibility includes only requirement determination, notthe design of the system.

System analysis and design (System Designers,applications developer): Here apart from the analysis work,

Analyst is also responsible for the designing of the newsystem/application.

Systems analysis, design, and programming (Programmeranalyst): Here Analyst is also required to perform as aprogrammer, where he actually writes the code to implement the

design of the proposed application.

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Who are the users of system

(System End Users)?

Hands-on users: They actually interact with the system. They are the people who

feed in the input data and get output data. Like person at thebooking counter of a gas authority. This person actually seesthe records and registers requests from various customers for

gas cylinders. Indirect end users:

Indirect end users who do not interact with the systemshardware and software. However, these users benefit from theresults of these systems. These types of users can be

managers of organization using that system.

User Manager: They have management responsibilities for application systems.

These oversee investment in the development or use of thesystem.

Senior managers:

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Business system concepts What is a System?

A system is simply a set of components that interact toaccomplish some purpose.

Nervous system of human body

Components can be brain, spinal cord, nerves, sensitive cellsunder your skin.

A business is also a system.

Define components

Every business system depends on Information system.

This system is the means by which data flow from oneperson or department to another via email, telephone links tocomputer system that generates periodic reports for varioususers.

Information system serve all the systems of a business,linking the different components in such a way that they

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Cont

Environment It is very important for a system to adapt itself to its

environment. Also, for a system to exist it should change

according to the changing environment.

Boundaries and Interfaces

Every system has defined boundaries within which it

operates. Beyond these limits the system has to interact

with the other systems.

Interfaces are another important element through whichthe system interacts with the outside world. System

interacts with other systems through its interfaces. Users

of the systems also interact with it through interfaces.

Therefore, these should be customized to the user needs.These should be as user friendl as ossible.

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Cont

System interact with their environments, which are anyentities outside the boundaries of the system.

An open system is a system which continuously interactswith its environment.

Close system are the type of system that do not interact withthe environment. Closed systems are closed off from the

outside environment, and all interaction and knowledge is

transmitted within the closed system only.

All ongoing systems are open, close system exists as a

concept.

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Categories of Information System Information systems differ in their business needs.

Also depending upon different levels in organization

information systems differ. There are three major information

systems:

Transaction Processing Systems (TPS): TPS are aimed at improving the routine business activities on

which all organizations depends.

A transaction is any event or activity that affects the

organization. For example, placing orders, billing customers, hiring

employees, deposit checks etc are all transactions. Any query

made to it is a transaction.

All firms process transactions as a major part of their daily

business activity.

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Cont Management Information Systems(MIS):

TPS are operation-oriented and MIS assist managers indecision making and problem solving.

They use the results of transaction processing and some otherinformation also.

It is a set of information processing functions.

MIS helps in taking structured decision, it means managersknow what factor to consider in making the decision.

Inventory reportingProduction scheduling

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Cont Decision Support Systems (DIS):

Not all decisions are of a recurring nature. Some occurs onlyonce or infrequently.

DSS assist higher management to make long term decisions ornot highly structured or semi structured decisions.

A decision is considered unstructured if there are no clearprocedures for making the decision and if not all the factors tobe considered in the decision can be readily identified inadvance.

These are not of recurring nature. In this case it is impossible to design predefine system reports

or formats and contents. A DSS therefore must have greaterflexibility..

The user should be able to produce customized reports bygiving particular data and format specific to particular situations.

The data needed may originate from different files or databases.

DSS plays vital role in decision making but does not replacemanager judgment.

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Cont

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Categories of Information System Characteristics

Transaction Processing System Substitutes computer-based processing for

manual procedures.

Deals with well-structured processes.

Includes record keeping applications.

Management information system Provides input to be used in the managerial

decision process. Deals with supportingwell structured decision situations. Typical

information requirements can be

anticipated.

Decision support system Provides information to managers who mustmake judgments about particular situations.

Supports decision-makers in situations that

are not well structured.

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Information System Components A system is a set of components working together to

achieve some goal. The basic elements of the system may

be listed as:

Resources:

Every system requires certain resources for the system to

exist. Resources can be hardware, software or liveware. Hardware resources may include the computer, its peripherals,

stationery etc.

Software resources would include the programs running on

these computers and the liveware would include the human beings required to

operate the system and make it functional.

For instance, a Banking system cannot function without the

required stationery like cheque books, pass books etc. such

systems also need computers to maintain their data and

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Procedures: Every system functions under a set of rules that govern the

system to accomplish the defined goal of the system. This set ofrules defines the procedures for the system.

For instance, the Banking systems have their predefined rules

for providing interest at different rates for different types ofaccounts.

Data/Information: Every system has some predefined goal. For achieving the goal

the system requires certain inputs, which are converted into therequired output. The main objective of the System is to producesome useful output. Output is the outcome of processing.Output can be of any nature e.g. goods, services or information.

However, the Output must conform to the customer'sexpectations. Inputs are the elements that enter the system and

produce Output. Input can be of various kinds, like material,

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Intermediate Data: Various processes process system's Inputs. Before it is

transformed into Output, it goes through manyintermediary transformations.

Therefore, it is very important to identify the IntermediateData.

For example, in a college when students register for anew semester, the initial form submitted by student goesthrough many departments. Each department adds their

validity checks on it. Finally the form gets transformed and the student gets a

slip that states whether the student has been registeredfor the requested subjects or not.

It helps in building the System in a better way.

Intermediate forms of data occur when there is a lot of

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System Development

Methodology

A software development methodology orsystemdevelopment methodology in software engineering isa framework that is used to structure, plan, and control

the process of developing an information system.

System development methodologies are promoted as ameans of improving the management and control of the

software development process, structuring and

simplifying the process, and standardizing the

development process and product by specifyingactivities to be done and techniques to be used.

It is often assumed that the use of a system

development methodology will improve system

development productivity and quality.

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System Development Life Cycle System development process starts when management

or sometimes a system development personnel realizethat a particular business system needs improvement.

The SDLC method is classically thought of as the set of

activities that analysts, designers and users carry out todevelop and implement an information system.

There are six activities that make up the SDLC.

All activities are closely related and inseparable, and

even the order of activities may be difficult to analyze.Analysts disagree on exactly how many phases there

are in the SDLC, but they generally laud its organizedapproach.

Different parts of project can be in various phases at thesame time.

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Activities of SDLC: Preliminary investigation

Determination of system requirement

Design of system

Development of software

System testing

Implementation and Evaluation

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Cont Feasibility study:

An important outcome of this phase is the determination thatthe system requested is feasible.

There are three aspects of feasibility study.

1. Technical feasibility:

Can the work for project be done with current equipment, existingsoftware technology, and available personnel?

If new technology is required, what is the likelihood that it can bedeveloped?

2. Economic feasibility:

Are there sufficient benefits in creating the system to make the costsacceptable?

Or, are the costs of not creating the system so great that the projectmust be undertaken?

3. Operational feasibility:

Will the system be used if it is developed and implemented?

Will there be resistance from users that will undermine the possiblea lication benefits?

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2. Determination of System Requirement: Detailed understanding of all important facts of the

business area under investigation is a main activity of

system analysis.

Analysts, working closely with employees and managers,must study the business process to answer these key

questions:

What is being done?

How it is being done? How frequently does it occur?

How great is the volume of transactions or decisions?

How well is the task being performed?

Does a problem exists?

If a problem exists, how serious it is?

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Cont To answer to these questions analyst talk to variety of

persons to gather details about the business process and

their opinions of why things happen as they do and their

ideas about changing the process.

Questionnaires are used to collect the information fromthe large group of people.

Detail investigation is also require to study of manuals

and reports, actual observation of work activity, collection

of sample forms and documents to understand thesystem.

After gathering all the details, the analysts study the

requirements data to identify features the new system

should have.

It should include the information the system should

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Cont

3. Design of System: This phase produces the details that state how a system

will meet the requirements identified during systemsanalysis.

This is also referred as logical design, where asdevelopment is referred as physical design.

System analyst begin the design process by identifyingreports and other outputs the system will produce.

Designers sketch the form or display as they expect it to

appear when the system is complete. This may be done on paper or on computer display, using

one of the automated system design tools.

The System design also specify data to input, calculatedand stored.

Designers select file structure and storage devices, the

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Cont The output of this phase contain document which can

contain Charts,

Tables,

Special symbols and

outline of forms. Designers provide complete and clearly outlined

software specification to programmers.

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4. Development of Software: Once the design is complete, most of the major decisions

about the system have been made.

The goal of the coding phase is to translate the design ofthe system into code in a given programming language.

A well written code reduces the testing and maintenanceeffort.

Since the testing and maintenance cost of software aremuch higher than the coding cost, the goal of coding

should be to reduce the testing and maintenance effort. Programmers are also responsible for documenting the

program, providing explanation of how and why certainprocedure are coded in specific ways.

Documentation is essential to test the program and carryon maintenance.

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5. System Testing: Testing is the major quality control measure employed

during software development. Its basic function is to

detect errors in the software.

After the coding phase, computer programs are availablethat can be executed for testing phases.

This implies that testing not only has to uncover errors

introduced during coding, but also errors introduced

during the previous phases. Thus, the goal of testing is to uncover requirement, design

or coding errors in the programs.

Different levels of testing are employed.

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The starting point of testing is unit testing. In this a moduleis tested separately and is often performed by the coderhimself simultaneously with the coding of the module. Thepurpose is to execute the different parts of the module codeto detect coding errors.

After this the modules are gradually integrated intosubsystem, which are then integrated themselveseventually form the entire system. During integration ofmodules, integration testing is performed. The goal of thistesting is to detect design errors, while focusing on testingthe interconnection between modules.

After the system is put together, system testing isperformed. Here the system is tested against tech systemrequirements to see if all the requirements are met and the

system performs as specified by the requirements. Finally,acce tance testin is erformed to demonstrate to the

http://www.freetutes.com/systemanalysis/sa9-unit-testing.htmlhttp://www.freetutes.com/systemanalysis/sa9-integration-testing.htmlhttp://www.freetutes.com/systemanalysis/sa9-integration-testing.htmlhttp://www.freetutes.com/systemanalysis/sa9-unit-testing.html

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During testing, the system is used experimentally toensure that software does not fail.

It will run according to its specifications and in the way

users expect.

Special test data are input for the processing and resultexamined.

In many organizations, testing is performed by persons

other than those who wrote it to ensure unbiased testing

and more reliable software.

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6. Implementation and Evaluation: Implementation is the process of having

System personal check out and put new equipment to use,

Train users,

Install the new application,

Construct any files of data needed to use it.

Pilot test can be done depending on size of organization and

risk to software.

As time goes, application have to be maintained, changes and

modification will be made to software, files or procedures tomeet emerging user requirements.

Implementation is an ongoing process.

Evaluation of the system is performed to identify its strengths

and weaknesses.

Actual evaluation can be done with followin dimensions:

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Operational Evaluation: Assessment of the manner in which the system functions, including

Ease of use,

Response time,

Suitability of information formats,

Overall reliability and

Level of utilization.

Organizational impact: Identification and measurement of benefits to the organization as

financial concerns

Operational efficiency,

Competitive impact. User management assessment:

Evaluation of the attitude of senior and user managers within organization, aswell as end user.

Development Performance: Check with overall development time and effort,

Conformance to budget and standards and other project management criteria.

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Structured Analysis Development

Method

What is structured Analysis? Structured Analysis focuses on specifying what the system or

application Required to do .

It does not state how the requirements should beaccomplished or how the application should be implemented.

ELEMENTS OF STRUCTURED ANALYSIS:1) Graphic Description2) Data Flow Diagram3) Data Dictionary

Graphic Description: To prepare a narrative outlining its features, identifying the

function it serves, describing how it interact with otherelements, etc.

Instead of words, it uses symbols or icons to create a graphical

modem of a system.

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Show details of the system without introducing manual orcomputer process, tape or disc file or any procedures.

Data Flow Diagram: It is known as System model.

Set of DFD consist of full description of a system. Follows top-down process.

Each process can be broken down into more detail DFD.

Shows processes and flow of data in and out of theseprocesses.

Does not show control structures (loops, etc.)

Uses layers to decompose complex systems

Data Dictionary: Definitions of elements in the system- data flows,

processes and data stores are described in detail in Data

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What is Structured Design? The goal of structured design is to create program

consisting of functionally independent module that

perform relatively independent of each other.

It is a program design technique, not a design method. Does not specify file, or database design, input and

output layout, processing sequence or hardware.

Lead to the specification of program modules that are

functionally independent. Fundamental tool is structure chart.

Describe interaction between independent modules and

data passing between modules that interact with each

other.

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System Prototype Method

What is a Prototype?A prototype is a working system that is developed to test ideas

and assumption about the new system.

It can accept inputs, perform calculations, produce information.

Design and information is evaluated by users.

Can be done effectively if data is real and the situation is live.

Reasons for System Prototyping Requirement are not always well defined. User may know only

that certain business areas need improvement or proceduresmust be changed. They dont know what they need.

Unique situations, about which developers have neitherinformation nor experience, high cost and high risk situation.

Ex. Sales data from mobile.

It is pilot or test model.

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In following conditions prototype model is useful: No system with the characteristic of one proposed has yet been

constructed by developers.

Essential features of the system are only partially known

Experience in using the system will significantly add to the list of

requirements the system should meet.

The system users will participate in development process.

Underlying principal is: Users can point to features theylike or dislike and so indicate shortcoming in an existing

and working system more easily then they can describethem in a theoretical or proposed system. Experience and

use produce more meaningful comments then analysis of

charts and narrative proposal.

It is an interactive process.

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Steps in Prototyping: Identify the users known requirements and features needed in

the system.

Develop a working system.

Use the prototype, noting needed enhancements andchanges. These expand the list of known system requirement.

Revise the prototype based on information gained through

user experience.

Repeat these steps as needed to achieve a satisfactory

system.

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When user and analyst decide that sufficientinformation has been gained from prototype, one of the

following alternative is selected:

The prototype is redeveloped. This alternative mean

complete reprogramming from scratch. The prototype is implemented as the complete system.

Performance efficiency and methods for user interaction

may be sufficient to allow the system to use as it is.

The project is abandoned. Gained enough information toshow that a system can not be developed to meet desired

objective.

Another prototype series is begun. Information gained

may suggest an entirely different approach or contrastingfeatures.

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Methods for prototype development: Speed of development is more important than efficiency.

Created quickly, within few days or weeks.

Relatively inexpensive to build, not so efficient.

Features and final touches like heading, title, page number onreports may be missing.

File organization may be temporary.

Documentation is avoided.

Emphasis is on trying ideas and providing assumption about

requirement.

Segments of programs may be taken from other systems or

from libraries of reusable program code.

There are certain application generators that generate other

programs, to support prototyping efforts.

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Tools for System Development

A tool is any device that when used properly, improve theperformance of a task.

Tools are grouped into the categories of system analysis,

design and development.

1) Analysis Tools: Assist systems specialists in documenting an existing

system, whether manual or automated, determining the

requirements for new application.a)Data Collection Tools: Captures details describingcurrent system and procedures. Document the activities.

Assist in requirement identification.

b)Charting Tools:Create graphic representations ofsystems and activities. Drawing and revising DFDs and icons

with structured analysis.c Dictionar Tools:Record and maintain descri tion of

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Cont

2) Design Tools:Assist in formulating the features of thesystem that will meet the requirements outlined during theanalysisa) Specification Tools: stating the features that shouldbe included in an application, such as input, output,

processing and control specification. Help in creating dataspecification.b) Layout Tools: Used to describe position of data,message and heading on display screen, reports andother input and output media.

3) Development Tools: Helps while translating designs intofunctioning application.a) Software Engineering Tools:Assist in formulatingsoftware designs.b) Code Generators: Produce source code and working