MODULE 1 [INCOMPLETE]

Question 1

MODULE 1

Answer 1

Requirements Engineering

Question 2

Course Learning Outccome

Answer 2

Evaluate software requirements and
appraise the processes involved in
discovering and documenting these
requirements.

Question 3

TOPIC LEARNING OUTCOMES

Answer 3

1. Evaluate the concepts of user and system requirements and why these requirements should be written in different ways.
2. Value the differences between functional and nonfunctional software requirements.
3. Appraise the main requirements engineering activities of elicitation, analysis, and validation, and the
   relationships between these activities.
4. Weigh why requirements management is necessary and how it supports other requirements engineering activities.

Question 4

Topics covered

Answer 4

Functional and non-functional requirements
Requirements engineering processes
Requirements elicitation
Requirements specification
Requirements validation
Requirements change

Question 5

The process of establishing the services that a customer requires from a system and the constraints under which it operates and is developed.

Answer 5

Requirements engineering

Question 6

the descriptions of the system services and constraints that are generated during the requirements engineering process.

Answer 6

System requirements

Question 7

It may range from a high-level abstract statement of a service or of a system constraint to a detailed mathematical functional specification.

Answer 7

requirement

This is inevitable as requirements may serve a dual function

May be the basis for a bid for a contract - therefore must be open to interpretation;

May be the basis for the contract itself -
therefore must be defined in detail;

Both these statements may be called
requirements.

Question 8

“If a company wishes to let a contract for a large software development project, it must define its needs in a sufficiently abstract way that a solution is not pre-defined. The requirements must be written so that several contractors can bid for the contract, offering, perhaps, different ways of meeting the client organization’s needs. Once a contract has been awarded, the contractor must write a system definition for the client in more detail so that the client understands and can validate what the software will do. Both of these documents may be called the requirements document for the system.”

Answer 8

Requirements abstraction (Davis)

Question 9

Types of requirement

Answer 9

User requirements
System requirements

Question 10

Statements in natural language plus diagrams of the services the system provides and its operational constraints. Written for customers.

Answer 10

User requirements

Question 11

A structured document setting out detailed descriptions of the system’s functions, services and operational constraints. Defines what should be implemented so may be part of a contract between client and contractor.

Answer 11

System requirements

Question 12

User and system requirements example

Answer 12

The Mentcare system shall generate monthly management reports
showing the cost of drugs prescribed by each clinic during that month.

1.1 On the last working day of each month, a summary of the drugs prescribed, their cost and the prescribing clinics shall be generated.
1.2 The system shall generate the report for printing after 17.30 on the
last working day of the month.
1.3 A report shall be created for each clinic and shall list the individual
drug names, the total number of prescriptions, the number of doses
prescribed and the total cost of the prescribed drugs.
1.4 If drugs are available in different dose units (e.g. 10mg, 20mg, etc)
separate reports shall be created for each dose unit.
1.5 Access to drug cost reports shall be restricted to authorized users as
listed on a management access control list.

Question 13

Readers of different types of requirements specification

Answer 13

User requirements
* Client managers
* System end-users
* Client engineers
* Contractor managers
* System architects

System requirements
* System end-users
* Client engineers
* System architects
* Software developers

Question 14

Any person or organization who is affected by the system in some way and so who has a legitimate interest

Answer 14

System stakeholders

Question 15

Stakeholder types

Answer 15

End users
System managers
System owners
External stakeholders

Question 16

Stakeholders in the Mentcare system

Answer 16

• Patients whose information is recorded in the system.
• Doctors who are responsible for assessing and treating patients.
• Nurses who coordinate the consultations with doctors and administer some treatments.
• Medical receptionists who manage patients’ appointments.
• IT staff who are responsible for installing and maintaining the system.

Question 17

Many _ methods argue that producing detailed system requirements is a waste of time as requirements change so quickly.

Answer 17

Agile

The requirements document is therefore always out of date.

Question 18

_ usually use incremental requirements engineering and
may express requirements as ‘user stories’.

Answer 18

Agile methods

This is practical for business systems but problematic for systems that require pre-delivery analysis (e.g. critical systems) or systems developed by several teams.

Question 19

Stakeholders in the Mentcare system

Answer 19

• A medical ethics manager who must ensure that the system meets current ethical guidelines for patient care.
• Health care managers who obtain management information from the system.
• Medical records staff who are responsible for ensuring that system information can be maintained and preserved, and that record keeping procedures have been properly implemented.

Question 20

Statements of services the system should provide, how the system
should react to particular inputs and how the system should behave in
particular situations.

Answer 20

Functional requirements

May state what the system should not do.

Question 21

Constraints on the services or functions offered by the system such as timing constraints, constraints on the development process, standards,
etc.

Answer 21

Non-functional requirements

Often apply to the system as a whole rather than individual features or services.

Question 22

Constraints on the system from the domain of operation

Answer 22

Domain requirements

Question 23

Describe functionality or system services

Answer 23

Functional requirements

• Depend on the type of software, expected users and the type of system where the software is used.
• Functional user requirements may be high-level statements of what the system should do.
• Functional system requirements should describe the system services in detail.

Question 24

Mentcare system: functional
requirements

Answer 24

• A user shall be able to search the appointments lists for all clinics.
• The system shall generate each day, for each clinic, a list of patients who are expected to attend appointments that day.
• Each staff member using the system shall be uniquely identified by his or her 8-digit employee number.

Question 25

* Problems arise when functional requirements are not precisely stated. * Ambiguous requirements may be interpreted in different ways by developers and users. * Consider the term ‘search’ in requirement 1

Answer 25

Requirements imprecision ## Footnote **Example:** * User intention – search for a patient name across all appointments in all clinics; * Developer interpretation – search for a patient name in an individual clinic. User chooses clinic then search.

Question 26

In principle, requirements should be both _ and _.

Answer 26

complete and consistent ## Footnote **Complete** - They should include descriptions of all facilities required. **Consistent** - There should be no conflicts or contradictions in the descriptions of the system facilities. In practice, because of system and environmental complexity, it is **impossible** to produce a complete and consistent requirements document.

Question 27

These define system properties and constraints e.g. reliability, response time and storage requirements. Constraints are I/O device capability, system representations, etc.

Answer 27

Non-functional requirements ## Footnote **Process requirements** may also be specified mandating a particular IDE, programming language or development method. Non-functional requirements **may be more critical** than functional requirements. If these are not met, the system **may be useless**.

Question 28

Types of nonfunctional requirement

Answer 28

* Product requirements * Organizational requirements * External requirements * (Usability, Efficiency, Performance, Security, Space, etc.)

Question 29

_ may affect the overall architecture of a system rather than the individual components.

Answer 29

Non-functional requirements ## Footnote For example, to ensure that performance requirements are met, you may have to organize the system to minimize communications between components. A single non-functional requirement, such as a security requirement, may generate a number of related functional requirements that define system services that are required. * It may also generate requirements that restrict existing requirements.

Question 30

Non-functional classifications

Answer 30

**Product requirements** * Requirements which specify that the delivered product must behave in a particular way e.g. execution speed, reliability, etc. **Organisational requirements** * Requirements which are a consequence of organisational policies and procedures e.g. process standards used, implementation requirements, etc. **External requirements** * Requirements which arise from factors which are external to the system and its development process e.g. interoperability requirements, legislative requirements, etc.