Software Requirements - Case Study

Question 1

What is the software requirements document?

Answer 1

The software requirements document states what is required of the system developers.

Question 2

What it’s included in the software requirements document?

Answer 2

It should include:

• Should include user requirements and specification of the system requirements.
• It’s NOT a design document, it should state WHAT the developers should do, but not HOW they should do it.

Question 3

Who uses the software requirements document?

Answer 3

It’s used by:

• System customers
• Managers
• System engineers
• System test engineers
• System maintenance engineers

Question 4

How the software requirements document is used by the “System customers”?

Answer 4

They specify the requirements on the document, which should meet their needs. Customers specify changes to the requirements.

Question 5

How the software requirements document is used by the “Managers”?

Answer 5

They plan the bid of the project and the development process.

Question 6

How the software requirements document is used by the “System engineers”?

Answer 6

They use the requirements document to understand what the system does.

Question 7

How the software requirements document is used by the “System test engineers”?

Answer 7

They use the requirements document to develop validation tests of the system.

Question 8

How the software requirements document is used by the “System maintenance engineers”?

Answer 8

They use the requirements document to understand the system and it’s parts.

Question 9

The amount of information in the requirements document depends on..?

Answer 9

The type of system and the approach to development used.

Question 10

The requirements document of a system developed incrementally will..?

Answer 10

Have less detail, because there will be several iterations each involving interviews with the client an other stakeholders.

Question 11

What is a IEEE standard?

Answer 11

It’s a requirements document standard that is mostly applicable to the requirements for large systems engineering projects.

Question 12

What IEEE standard will be used in class?

Answer 12

IEEE/ANSI 830-1998

Question 13

What are the parts of a requirements document IEEE

Answer 13

They are 10 secctions;

• Preface
• Introduction
• Glossary
• User requirements definition
• System architecture
• System requirements specification
• System models
• System evolution
• Appendices
• Index

Question 14

Requirement document: Preface

Answer 14

This should define the version history, and the changes made on each version.

Question 15

Requirement document: Introduction

Answer 15

This should describe the need for the system, why it’s important to the organization. It also should include all the functions of the system and how it relates with other systems.

Question 16

Requirement document: Glossary

Answer 16

This should define the technical terms used in the document.

Question 17

Requirement document: User requirements

Answer 17

Here is defined all the services provided by the user. Also all the nonfunctional requirements should be in this section.

Question 18

Requirement document: System architecture

Answer 18

This section should present a high-level overview of the anticipated system architecture, showing its functions across the system modules.

Question 19

Requirement document: System requirements specification

Answer 19

This should describe the functional and nonfunctional requirements.

Question 20

Requirement document: System models

Answer 20

This might include graphical system models that show all the relationships between the system components and the system environment.

Question 21

Requirement document: System evolution

Answer 21

This should include assumptions on which the system based and any changes due to hardware evolution, change in user needs and so on.

Question 22

Requirement document: Appendices

Answer 22

These should provide information about specific information that is related with the application of the system.

Question 23

Requirement document: Index

Answer 23

Indexes of the document.

Question 24

What is the difference between “User requirements” and “System requirements” when writing them down?

Answer 24

User requirements are written in a understandable language, that do not have technical background. System requirements are more detailed requirements that may have technical information.

Question 25

Different ways of writing specifications: Natural Language

Answer 25

Use of numbered sentences in natural language. Each number express one requirement.

Question 26

Different ways of writing specifications: Structured natural Language

Answer 26

The requirements are written on a standard form or template. Each field provides information about an aspect of the requirement.

Question 27

Different ways of writing specifications: Design description language

Answer 27

This approach uses a language like programming language, but with more abstract features to specify the requirements.

Question 28

What are functional requirements?

Answer 28

They are the "how" the system responds and what it does.

Question 29

What are nonfunctional requirements?

Answer 29

All the limitations of the services provided by the system.

Question 30

What is the differences between requirements and design?

Answer 30

The requirements state what the system SHOULD DO and the design should describe HOW IT DOES THIS.

Question 31

Different ways of writing specifications: Graphical notations

Answer 31

UML, graphic models supplemented with text annotations.

Question 32

Different ways of writing specifications: Mathematical specifications

Answer 32

These notations are based on mathematical concepts such as finite-state machines or sets.

Question 33

Which are the activities of the requirements engineering process?

Answer 33

- Requirements elicitation - Requirements analysis - Requirements validation - Requirements management

Question 34

Explain the requirements elicitation

Answer 34

It's focused on having interviews with all the stakeholders.

Question 35

Mention two types of interview.

Answer 35

- Closed: interviews based on predetermined list of questions. - Open: interviews where various issues are explored with stakeholders.

Question 36

Parts of an effective interviewing

Answer 36

- Be open minded, avoid preconceived ideas about the requirements. - Some really good ideas come out when the interview is focused on the stakeholders. - Work with the interviewee using springboard questions or a prototype system.

Question 37

Explain the requirements analysis

Answer 37

The analysis of requirements check that all the information obtained from the elicitation is correct. - Different stakeholders may have conflicting requirements. - Organizational and political factors may influence the system requirements. - New stakeholders may emerge and the business environment may change.

Question 38

What are scenarios? What should include?

Answer 38

Scenarios are real life examples of how a system can be used. Scenarios should include: -A description of the starting situation. -A description of the normal flow of events. -A description of what can go wrong. -Information about other concurrent activities. -A description of the state when the scenario finishes.

Question 39

Each scenario is described from the point of view of an..?

Answer 39

Actor. | A person or a device that interacts with the software

Question 40

Explain the requirements validation

Answer 40

Validation is concerned with demonstrating that the requirements define the system that the customer really wants.

Question 41

State five verifications that should be performed in the validation phase.

Answer 41

- Validity: Are the functions provided by the system supporting the customer's needs? - Consistency: Are there any conflicts in the requirements? - Completeness: Are all functions/features required by the customer included? If not, is there any cost/benefit analysis? - Realism: Can the requirements be implemented given available budget and technology? - Verifiability: Can the requirements be checked?

Question 42

Explain the requirements management

Answer 42

Is the process of managing changing requirements during the requirements engineering process and system development.

Question 43

Why requirements change?

Answer 43

a) New hardware may be introduced, it may be necessary to interface the system with others systems, business priorities may change and new legislation and regulations may be introduced. b) The people who pay for a system and the users of that system are rarely the same people.

Question 44

What is planning? (Requirements management) Mention some decisions of planning.

Answer 44

Planning establish the level of requirements management detail that is required. Some of the decisions: - Identification: Each requirement must be uniquely identified so that it can be cross-referenced with other requirements. - Change management process: Set of activities that assess the impact and cost changes. - Tractability policies: These policies define the relationships between each requirement and between the requirements and the system design that should be recorded. - Tool support: Tools that may be used.

Question 45

Explain the phases of "change management"

Answer 45

1) Problem analysis and change specification: Analyze if the change is valid, if not request more information, the request may change, may be more specific, or may be dropped. 2) Change analysis and costing: The effect of the change is assessed by tracing how the change will affect the rest of the system. A cost is assigned and a decision is made. 3) Change implementation: The requirements document is changed and if necessary the design and implementation are changed.

Question 46

Define implementation phase

Answer 46

This phase converts the specification of the system into an executable.

Question 47

Define design phase

Answer 47

Involves the construction of models which help the analyst to understand the functionality of the system and to communicate with customers.

Question 48

Abstract models of a system allow:

Answer 48

- Communicating behavior or functionalities between the requirement analysis and the implementation phase. - Help in the documentation process. - Help the implementors and designers focus on the structure or architecture of the entire software system. - Helps capturing interactions between the system and the external environment.

Question 49

Explain the modeling and system perspectives

Answer 49

1) External: represents the context or environment of the system. 2) Interaction: represents the interactions between a system and its environment, or between the components of a system. 3) Structural: represents the organization of a system or the structure of the data that is processed by the system. 4) Behavioral: represents the dynamic behavior of the system and how it responds to events.

Question 50

Mention the visual modeling capabilities

Answer 50

- Captures business processes by defining the software system requirements from the user's perspective. - Displays modeling elements in many ways, so that they can be viewed at different levels of abstraction. - Capture the logical software architecture independent of the implementation language. - Enable reuse of parts of a system or an application by creating components of our design.

Question 51

What is UML?

Answer 51

UML stands for United Modeling Language. It combines the best of: - Data modeling concepts. - Business Modeling - Object Modeling - Component modeling

Question 52

Why is UML useful?

Answer 52

- Can make mistakes on paper, before the code is written and debugged. - Is a better way of communicating ideas. - It's independent of any particular programming language and supports higher level of collaboration between developers and non-developers. - Can help in tapping into a wealth of existing designs that exploits other's experience.