INFO2010 - L3 System requirements

Question 1

TELOS

Answer 1

Technical
Economic
Legal
Operational
Schedule

Question 2

Technical feasibility

Answer 2

Can a solution be supported with existing technology?
Hardware and software capability, reliability and availability
Concerned with determining the possibility and practicability of using existing and modern IT to develop the proposed system

Question 3

Economic feasibility

Answer 3

Assesses budgetary & financial constraints on proposed IT system
Cost savings, increased revenue, decreased investment, increased profits
Is existing tech cost effective - will costs be offset by the benefits?

Question 4

Operational feasibility

Answer 4

Determining whether existing or proposed procedures & practices are adequate for the purposes of the proposed system
Will the solution work within the org if implemented?
Give consideration to education, training & development required to operate proposed info system
End user acceptance
Management control
Customer, supplier and government requirements

Question 5

Schedule feasibility

Answer 5

Assists in determining practicality and acceptability of the time-frame for development of the proposed information system

Question 6

REQUIREMENTS DEFINITION

Answer 6

COARSE GRAIN FR
- system functions defined in an abstract way
SYSTEM PROPERTIES
- non funct. reqs for the sys in general are defined
UNDESIRABLE characteristics
- unacceptable system behaviour is specified

Question 7

Information system components

from Lester

Answer 7

PROCESSING (comms)
 - create, 
update/edit, 
enquiries (ad-hoc),
reports (regular),
delete
INTERFACE
 - user
DATA (network)
 - files,
records, 
fields,
database relationships

Question 8

Information system requirements FR

from Lester

Answer 8

Processing - what must be done FR
Create, update, enquire, report, delete
Data - what sort of data must b processed FR
files, records, fields
Interface- what protocols must be used FR
user, network, telecomms

Question 9

Information system requirements NFR

from Lester

Answer 9

Availability?
Security?
Access?
Monitoring?
Constraints?
Response time?

Question 10

Requirements

Answer 10

/ (Need) –> Solution
Problem->Cause - Req tackles cause-> Sol
\ (Wish) –> Solution

Question 11

Requirements Catalogue

Answer 11

ID
Who has this req
Priority (Optional, Desirable, Mandatory)
Requirement (updates, enquiries, interfaces, reports, data)
Target value (security, availability, audit & control, service level, monitoring, constraints, access)
Acceptable range
Comments (benefits, suggested solutions)
Related docs
Resolution (Where in the analysis, specification or design is this requirement addressed?)

Question 12

Requirements validation

Answer 12

Demonstrate the requirements define the system which the customer really wants
Very important as req error costs are high
Prototyping - important technique

Question 13

Requirements validation - aspects to be checked:

Answer 13

Validity - reqs must be a compromise across user community
Consistency - one req should not conflict with another
Completeness - incl all functs & constrts intended by sys user
Realism - must be realisable

Question 14

Requirements validation - in practice

Answer 14

Must not be after req doc is complete

Regular req reviews with both users and sw engineers essential during req definition

Question 15

Prototyping

Answer 15

Is a working model of one or more aspects of a system
Involves users early in development
Quick and inexpensive
Important req validation technique
Gives users hands on experience, they can see how it supports their work
Allows rapid dev and testing of ideas
USeful when user reqs undefined

Question 16

Prototyping types

Answer 16

Throw away
Evolutionary
Incremental

Question 17

Prototyping - Throw away

Answer 17

Used to test an idea
Discarded when dev starts
Not developed using final sw or hw

Question 18

Prototyping - Evolutionary

Answer 18

Developed and modified till finally in state where it can become the operational system
Standards used have to be carefully considered

Question 19

Prototyping - Incremental

Answer 19

Strictly speaking - not prototyping
Operational system developed and implemented in small stages
Feedback from earlier stages can influence dev in later stages

Question 20

Advantages of prototyping

Answer 20

Learning by doing
Improved communication
Improved user involvement
Clarification of partially-known requirements
Demonstration of the consistency and completeness of a spec
Reduced need for docs
Reduced maintenance costs (i.e. changes after sys goes live)
Production of expected results

Question 21

Disadvantages of prototyping

Answer 21

Users might misunderstand the role of prototype
Lack of project standards is possible
Lack of control
Additional expense
Machine efficiency
Close proximity of developers

Question 22

System Life Cycle

Answer 22

Feasibility
Analysis - > Requirements
Design
Implement->Pilot and Test->Deploy
Maintain/Evolution
Decommission

Question 23

Analysis

Answer 23

Process - the set of activities lead to production of:

• requirements definition
• requirements specification

Question 24

Feasibility studies

Answer 24

Is is realistic to address a problem or opportunity under consideration?
Used to investigate the information needs of prospective users:
- estimate if current sw & hw might satisfy users
- is it cost effective from biz POV - can it be dev within current budget
- should be quick and cheap and inform decision go/no go