Software Design Lesson 2-4

Question 1

contains a description of what the system will do without
describing how it will do it.

Answer 1

Requirements

Question 2

Without _______
– Developers do not know what to build
– Customers do not know what to expect
– What to validate

Answer 2

well-written document

Question 3

Crucial Process Steps of requirement engineering

Answer 3

• Problem Statement
• Requirements Elicitation
• Requirements Analysis
• Requirements Documentation
• Requirements Review
• SRS

Question 4

the disciplined application of
proven principles, methods, tools, and notations to describe a
proposed system’s intended behavior and its associated
constraints.

Answer 4

Requirement Engineering

Question 5

It may act as a contract between developer and customer.

Answer 5

SRS

Question 6

Types of Requirements

Answer 6

• Known Requirements
• Unknown Requirements
• Undreamed Requirements

Question 7

Anyone who should have some direct or indirect
influence on the system requirements.

Answer 7

Stakeholder

Question 8

It describes what the software has to
do. They are often called product features.

Answer 8

Functional requirements

Question 9

These are mostly quality requirements. That stipulates how well the software does,
what it has to do.

Answer 9

Non-Functional requirements

Question 10

These are written for the users and include a functional and non-functional requirement

Answer 10

User requirements

Question 11

Derived from User requirements

Answer 11

System Requirement

Question 12

The user system requirements are the parts of what document?

Answer 12

software requirement and specification (SRS) document

Question 13

TYPES OF INTERFACES

Answer 13

• Procedural interfaces (also called Application Programming Interfaces (APIs)).
• Data structures
• Representation of data.

Question 14

“evaluation or analysis of the potential impact of a
proposed project or program.”

Answer 14

Purpose of feasibility study

Question 15

They introduced Use Case approach for elicitation & modeling

Answer 15

Ivar Jacobson & others

Question 16

It is a structured outline or template for the description of user requirements modeled in a structured language like English.

Answer 16

Use Cases

Question 17

These are unstructured descriptions of user requirements.

Answer 17

Use case Scenarios

Question 18

It lies outside the system model, but interacts with it in some way

Answer 18

An actor or external agent

Question 19

He is the one having a goal requiring the assistance of the system.

Answer 19

Primary Actor

Question 20

He is the one from which System needs assistance.

Answer 20

Secondary Actor

Question 21

It describes the sequence of interactions between actors and the system necessary to deliver the services that satisfies the goal.

Answer 21

Use Case

Question 22

Use Case captures who (_____) does what (______) with the system, for what purpose (_____), without dealing with system internals.

Answer 22

1. actor
2. interaction
3. goal

Question 23

conditions that need to be satisfied for the use
case to perform

Answer 23

Pre conditions

Question 24

Define the different states in which we expect the system to be in, after the use case executes.

Answer 24

Post Conditions

Question 25

List the primary events that will occur when this use case is executed.

Answer 25

Basic Flow

Question 26

Any Subsidiary events that can occur in the use case should be separately listed.

Answer 26

Alternative Flows

Question 27

Requirements Analysis Steps

Answer 27

- Draw the context Diagram - Develop prototype (optional) - Model the Requirements - Finalize the Requirements

Question 28

It show the flow of data through the system.

Answer 28

Data Flow Diagrams

Question 29

A source of system inputs or sink of system outputs

Answer 29

Source or sink

Question 30

A repository of data, the arrowhead indicate net input and net outputs to store

Answer 30

Data Store

Question 31

It called fundamental system model or context model represents entire software element as a single bubble with input and output data indicating by incoming & outgoing arrows.

Answer 31

Level 0 DFD

Question 32

These are simply repositories to store information about all data items defined in DFD.

Answer 32

Data Dictionaries

Question 33

x= a+b

Answer 33

x consists of data element a & b

Question 34

x={a/b}

Answer 34

x consists of either a or b

Question 35

x=(a)

Answer 35

x consists of an optional data element a

Question 36

x= y{a}

Answer 36

x consists of y or more occurrences

Question 37

x={a}z

Answer 37

x consists of z or fewer occurrences of a

Question 38

x=y{a}z

Answer 38

x consists of between y & z occurrences of a{

Question 39

It is a detailed logical representation of data for an organization and uses three main constructs.

Answer 39

Entity-Relationship Diagrams

Question 40

basic modeling notation contains three main constructs

Answer 40

- data entities - relationships - attributes

Question 41

the description of all entities to which a common definition and common relationships and attributes apply

Answer 41

Entity Type

Question 42

These are represented by diamond notation in a ER diagram.

Answer 42

Relationships

Question 43

Degree of relationships

Answer 43

- Unary - Binary - Ternary

Question 44

an attribute or combination of attributes that uniquely identifies each instance of an entity type.

Answer 44

candidate key

Question 45

What is SRD?

Answer 45

Structured requirements definition

Question 46

Characteristics of a good SRS

Answer 46

✓ Correct ✓ Unambiguous ✓ Complete ✓ Consistent ✓ Ranked for important and/or stability ✓ Verifiable ✓ Modifiable ✓ Traceable

Question 47

An SRS is correct if and only if every

Answer 47

every requirement stated therein is one that the software shall meet.

Question 48

An SRS is unambiguous if and only if

Answer 48

every requirement stated therein has only one interpretation.

Question 49

An SRS is complete if and only if

Answer 49

it includes the following elements (i) All significant requirements, whether related to functionality, performance, design constraints, attributes or external interfaces. (ii) Responses to both valid & invalid inputs. (iii)Full Label and references to all figures, tables and diagrams in the SRS and definition of all terms and units of measure.

Question 50

An SRS is consistent if and only if

Answer 50

no subset of individual requirements described in it conflict.

Question 51

An SRS is verifiable, if and only if

Answer 51

every requirement stated therein is verifiable.

Question 52

An SRS is modifiable, if and only if,

Answer 52

its structure and style are such that any changes to the requirements can be made easily, completely, and consistently while retaining structure and style.

Question 53

An SRS is traceable, if

Answer 53

the origin of each of the requirements is clear and if it facilitates the referencing of each requirement in future development or enhancementdocumentation.

Question 54

Process of understanding and controlling changes to system requirements.

Answer 54

Prototyping

Question 55

They are core requirements & are related to main activity of the organization

Answer 55

Enduring requirements

Question 56

likely to change during the software development lifer cycle or after delivery of the product

Answer 56

Volatile requirements

Question 57

- Product is constructed without specifications or any attempt at design - Adhoc approach and not well defined - Simple two phase model

Answer 57

Build & Fix Model

Question 58

Suitable for small programming exercises of 100 or 200 lines

Answer 58

Build & Fix Model

Question 59

This model is easy to understand and reinforces the notion of “define before design” and “design before code”.

Answer 59

Waterfall Model

Question 60

The model expects complete & accurate requirements early in the process, which is unrealistic

Answer 60

Waterfall Model

Question 61

After every cycle a useable product is given to the customer.

Answer 61

Incremental Process Models

Question 62

This model has the same phases as the waterfall model, but with fewer restrictions. Generally the phases occur in the same order as in the waterfall model, but they may be conducted in several cycles. Useable product is released at the end of the each cycle, with each release providing additional functionality.

Answer 62

Iterative Enhancement Model

Question 63

- Developed by IBM in 1980 - User participation is essential - Build a rapid prototype - Give it to user for evaluation & obtain feedback - Prototype is refined

Answer 63

The Rapid Application Development (RAD) Model

Question 64

This model differs from iterative enhancement model in the sense that this does not require a useable product at the end of each cycle. In evolutionary development, requirements are implemented by category rather than by priority.

Answer 64

Evolutionary Process Models

Question 65

This model is useful for projects using new technology that is not well understood. This is also used for complex projects where all functionality must be delivered at one time, but the requirements are unstable or not well understood at the beginning.

Answer 65

Evolutionary Process Models

Question 66

* Linear model * “Rapid”

Answer 66

Prototyping Model

Question 67

Barry Boehm recognized this and tired to incorporate the “project risk” factor into a life cycle model

Answer 67

Spiral Model

Question 68

The radial dimension of the model represents the cumulative costs. Each path around the spiral is indicative of increased costs.

Answer 68

Spiral Model

Question 69

each phase is completed with a review by the people concerned with the project (designers and programmers)

Answer 69

Spiral Model

Question 70

* Developed by I.Jacobson, G.Booch and J.Rumbaugh. * Software engineering process with the goal of producing good quality maintainable software within specified time and budget.

Answer 70

The Unified Process

Question 71

The Unified Process Model was developed through a series of fixed length mini projects called what?

Answer 71

iterations

Question 72

defines scope of the project.

Answer 72

Inception

Question 73

the objectives are translated in design & architecture documents.

Answer 73

Construction

Question 74

involves many activities like delivering, training, supporting, and maintaining the product.

Answer 74

Transition

Question 75

2 TYPES OF DATA DICTIONARY

Answer 75

1. Yourdon 2. Warnier-Orr

Question 76

a group of smaller structures and elements

Answer 76

Data structures

Question 77

used to represent the data structure.

Answer 77

algebraic notation

Question 78

defined with descriptive information, length and type of data information, validation criteria, and default values

Answer 78

Data elements

Question 79

This is an optional entry that allows the analyst to build automated data dictionary entries

Answer 79

Element ID

Question 80

A graphic picture of a logical system from the viewpoint of its data

Answer 80

DATA FLOW DIAGRAM

Question 81

a group of interrelated procedures used for a business function, with an identifiable boundary, working together for some purpose

Answer 81

System

Question 82

separation of a whole into its component parts

Answer 82

Analysis

Question 83

to create, fashion, execute, or construct according to plan

Answer 83

Design

Question 84

show how the current system flows

Answer 84

PHYSICAL DATA FLOW DIAGRAMS

Question 85

show the data flow, structure, and requirements of a new system

Answer 85

LOGICAL DATA FLOW DIAGRAMS

Question 86

2 TYPES OF DATA FLOW DIAGRAM

Answer 86

- DeMarco & Yourdon - Gane & Sarson

Question 87

Either a) receive info from system, b) trigger system into motion, or c) provide new information to system

Answer 87

Entity

Question 88

are the activities (manual and automated) that transform the inputs, transport data from process to process, stores the data, and produce the outputs of a system.

Answer 88

Process

Question 89

is the resting place of the data in a system.

Answer 89

Data Store

Question 90

processes transform the data in data store

Answer 90

store, add, delete, update

Question 91

Is the data in motion. Data can move from the outside (source) into a process.

Answer 91

Data Flow

Question 92

7 steps in CREATING DFD

Answer 92

1. Create a preliminary Context Diagram 2. Identify Use Cases, i.e. the ways in which users most commonly use the system 3. Create DFD fragments for each use case 4. Create a Level 0 diagram from fragments 5. Decompose to Level 1,2,… 6. Go to step 1 and revise as necessary 7. Validate DFDs with users.