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Q. 2 Describe in brief the various phases of system development life cycle?

Ans: System development life cycle (SDLC) refers to a methodology for developing

systems. It provides a consistent framework of tasks and deliverables needed to develop

systems. The SDLC methodology may be condensed to include only those activities

appropriate for a particular project, whether the system is automated or manual, whether

it is a new system, or an enhancement to existing systems. The SDLC methodology

tracks a project from an idea developed by the user, through a feasibility study, systems

analysis and design, programming, pilot testing, implementation, and post-

implementation analysis. Documentation developed during the project development is

used in the future when the system is reassessed for its continuation, modification, or

deletion.

SDLC Phases

Phases in SDLC are Planning, Analysis, Design, Implementation, and

Maintenance/Sustainment/Staging

Project planning, feasibility study: Establishes a high-level view of the intended

project and determines its goals.

2005 by Prentice Hall2005 by Prentice Hall1-11

SDLC Planning Phase

Identify, analyze,

prioritize, andarrange IS needs

Systems analysis, requirements definition: Refines project goals into defined

functions and operation of the intended application. Analyzes end-user

information needs.

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2005 by Prentice Hall2005 by Prentice Hall1-12

SDLC Analysis Phase

Study and

structure system

requirements

Systems design: Describes desired features and operations in detail, including

screen layouts, business rules, process diagrams, pseudo code and other

documentation.

Convert

recommended

solution to system

specifications

Logical design:

functional features

described

independently of

computer platform

Physical design:

logicalspecifications

transformed to

technology-

specific details

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Implementation (Development): The real code is written here.

Integration and testing: Brings all the pieces together into a special testing

environment, then checks for errors, bugs and interoperability.

Acceptance, installation, deployment: The final stage of initial development,

where the software is put into production and runs actual business.

Maintenance: What happens during the rest of the software's life: changes,

correction, additions, moves to a different computing platform and more.

Code, test, install,

and support theinformation system

Systematically

repair and

improve the

information

system

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Q. 3 Write short note on Open and closed system.

Ans-The closed system is defined as the system which does not have any inputs and does

not send any signals outside. The open system is defined as the system which does have

inputs and does send signals outside. The earth is included under it in respect to energy.

The earth receives energy and sends to the atmosphere. The sun is the main source of

energy to earth. The ability of sun to produce energy is related to the process of nuclear

fusion. It occurs by the help of hydrogen atoms. The matter is transformed to energy. The

high energy radiations are removed. Out of the total energy only a few amount of energy

is picked by the auto trophs and the rest is dissipated as a heat. This amount of energy is

used to manufacture to their own food as well as food for the other organisms. The

trapped energy is also dissipated. So, the earth receives the energy and releases the infra

red waves as energy waves. The earth can also acts as a closed system with respect to the

materials. The meteors which come to the earth have a very little amount of material. So,

the earth neither gets the material from outside and nor it gives the material outside. The

earth forms the atmosphere and it neither receives the gases and nor it gives the gases to

outside environment.

Q. 4 What is prototyping? Explain in brief.

Ans: Prototyping is the process of quickly building and demonstrating a working system

only to help establish user requirements and nail down the "look and feel" for how the

system will work in the end (its design). This process is conducted in a mini cycle where

you create a product demo, let the user play with it, listen to the user's feedback to

problems, correct them and repeat.

Some advantages are that....

1) It quickly flushes out system requirements that the user may have not known or

forgot to tell you about before you create the whole thing.

2) Provides visual feedback to users and gives them something to tinker with and

find problems in design.

3) Nails down what should and should not be included before time is wasted

working on features that never were needed in the first place.

Disadvantages...

1) It can be time consuming if users continuously tweak demo after demo.

Prototyping iterations should be limited to 3 or 4 before saying that "you need to

move on"

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2) If you get a perfectionist on the team, the rough not fully completed demos will

drive them nuts and could slow down the process if designers invest too much

time in fixing little details in a demo that will eventually be thrown away.

3) Since the demo is not really a complete working model, it can't find all the

problems that will be in a full working version. They are often not tied to real

production data and thus some design problems may occur later. Use prototyping

in addition to other methodologies to help fully explore all different angles to a

project before investing time and money into something that grows too

complicated or bloated.

These advantages and disadvantages should be enough to get you started and nailing

down what prototyping is and how it can be used during the requirement gathering /

design phase of the system development lifecycle (SDLC). Combined with Rapid

Application Development (RAD) techniques, it can be very effective in creating relevant

and exhaustive system requirements.

Q. 5 What is structured analysis? Explain

Ans: The term structured analysis, within the domain of software development, describes

the set of techniques used in the design of computer applications. These techniques help

explain the required steps within a computer application in a more humanistic manner.

The results of a thorough structured analysis and design approach typically describe both

the physical and logical layers of the computer application.

Software engineering is a complex process that requires intricate detail on the

specifics about how the software application will function. The early pioneers of softwareengineering realized that this complexity required a method of formality that would not

only document the system, but also explain the process in terms that could be understood

by the general public. Structured analysis is the process that is used for documenting this

complexity.

Structured analysis and design are broken into four primary domains within

application architecture. These are the data flows, data models, structure charts, and state

models. All of these domains are typically represented in a manner starting from a

summary level and progressing into a detail level of interpretation.

One of the key tools used in structured analysis for this visualization approach are

data flow diagrams. Data flow diagrams were first introduced into as a method of

capturing the flow of data within an application, explaining how that data moves from

process to process. Each process is connected using a line with an arrow, representing the

flow of data between the processes. Data models represent the relationships between data

within an application in a logical manner. These models further clarify the data needed to

complete the processes defined in the data flow diagrams. There are many tools and

techniques used for the creation of data models, but the primary goal is to define the

usage of data and the relationships between one data element and another.

Structure charts are used to define the summary structure flow from one processto another. These charts are used as a blueprint on how an application will communicate

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between processes or modules. Structure charts follow afunctional

decompositionapproach, staring at a high-level design and breaking down into a detail

design.

The final component necessary in structured analysis is state models. They define

the state or behavior of an application. These models are joined with data flow models to

define the events of an application.

These four primary domains make up the necessary techniques to define a system

with structured analysis and design. While there are other methods that can be used for

software development interpretation, structured analysis remains a viable option for

defining the complex inner working of a software application.

Q. 7 Explain DFD and Decision tree.

Ans: DFD:- Data flow diagrams represent the logical flow of data within the system.

DFD do not explain how the processes convert the input data into output. They do not

explain how the processing takesplace.DFD uses few symbols like circles and rectanglesconnected by arrows to represent data flows. DFD can easily illustrate relationships

among data, flows, external entities stores.DFD can also be drawn in increasing levels of

detail, starting with a summary high level view and proceeding o more detailed lower

level views. Rounded rectangles represent processes that transform flow of data or work

to be done. Rectangle represents external agents- the boundary of the system. It is source

or destination of data.The open-ended boxes represent data stores, sometimes called files

or databases. These data stores correspond to all instances of a single entity in a data

model. Arrow represents data flows, inputs and outputs to end from the processes. A

number of guideline should be used in DFD

Choose meaningful names for the symbols on the diagram.

Number the processes consistently. The numbers do not imply thesequence.

Avoid over complex DFD.

Make sure the diagrams are balanced

A decision tree is a decision support tool that uses a tree-like graph or model ofdecisions and their possible consequences, including chance event outcomes, resource

costs, and utility. It is one way to display an algorithm.Decision trees are commonly used

in operations research, specifically in decision analysis, to help identify a strategy most

likely to reach a goal.

In decision analysis a decision tree and the closely related influence diagram is

used as a visual and analytical decision support tool, where the expected values (or

expected utility) of competing alternatives are calculated.

A decision tree consists of 3 types of nodes:

Decision nodes - commonly represented by squares

Chance nodes - represented by circles

End nodes - represented by triangles

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Decision trees are commonly used in operations research, specifically in decision

analysis, to help identify a strategy most likely to reach a goal. If in practice decisions

have to be taken online with no recall under incomplete knowledge, a decision tree

should be paralleled by a probability model as a best choice model or online selection

model algorithm. Another use of decision trees is as a descriptive means for calculating

conditional probabilities.

Decision trees, influence diagrams, utility functions, and other decision analysis

tools and methods are taught to undergraduate students in schools of business, health

economics, and public health, and are examples of operations research or management

science methods.

Q. 9 Write short note on Data Dictionary.

Ans: Data Dictionary-The data dictionary is used to create and store definitions of data,

location, format for storage and other characteristics. The data dictionary can be used to

retrieve the definition of data that has already been used in an application. The datadictionary also stores some of the description of data structures, such as entities,

attributes and relationships. It can also have software to update itself and to produce

reports on its contents and to answer some of the queries. Determining the Information

Requirement The sole purpose of the MIS is to produce such information which will

reduce uncertainty risk in a given situation.

The difficulty to determine a correct and complete set of information is on

account of the factors given below:

1) The capability constraint of the human being as an information processor, aproblem solver and a decision-maker.

2) The nature and the variety of information in precise terms.3) Reluctance of decision-makers to spell out the information for the political and

the behavioural reasons.

4) The ability of the decision-makers to specify the information. In spite of thesedifficulties,methods are evolved based on the uncertainty scale, starting from the

low to the high level of uncertainty. If the uncertainty is low, seeking information

requirement or needs is easy as against a very high level of uncertainty.

There are four methods of determining the information requirements. They are:

Asking or interviewing

Determining from the existing system

Analysing the critical success factors

Experimentation and modelling.