1. Approaches to System Development
Lecture 2

2. Aids to Assist in Analysis and Design
Methodologies
Comprehensive guidelines to follow for completing every SDLC activity
Collection of models, tools, and techniques
Models
Representation of an important aspect of the real world
Diagrams and charts
Project planning aids

3. Some Models Used in System Development Figure 3-1

4. Aids to Assist in Analysis and Design
Tools
Software support that helps create models or other project components
From simple drawing programs to complex CASE tools

5. Some Tools Used in System Development Figure 3-2

6. Aids to Assist in Analysis and Design
Techniques
Collection of guidelines that help analyst complete system development activity or task
Step-by-step instructions
General advice

7. Some Techniques Used in System Development Figure 3-3

8. Components of a Methodology Figure 3-4
Relationships Among
Components of a Methodology Figure 3-4

9. Our approach to System Development
Traditional Approach
Structured system development
Structured analysis
Structured design
Structured programming
Collectively referred to as structured analysis and design technique (SADT)

10. Structured Analysis
Helps developer define what the system needs to do (processing requirements)
Data to store and use
Inputs and outputs
How functions work together
DFDs and ERDs commonly show results of structured analysis

11. DFD Created Using the Structured Analysis Technique Figure 3-8

12. Structured Analysis Figure 3-9
ERD Created During
Structured Analysis Figure 3-9

13. Structured Analysis -> Structured Design -> Structured Programming - Figure 3-10

14. Beginning the Analysis:
Investigating System
Requirements

15. Analysis Phase in More Detail Figure 4-1

16. Activities of the Analysis Phase/and Key Questions Figure 4-2

17. Functional and Technical Requirements
System requirements – all capabilities and constraints
Functional requirements
Activities the system must perform
Based on procedures and business functions
Documented in analysis models
Technical requirements
Describes operating environment or performance objectives
Documented in narrative descriptions of technical requirements

18. Stakeholders People with interest in system success
Three primary groups
Users (use system)
Clients (pay for system)
Technical staff (ensure system operation)

19. Users as Stakeholders User roles Business users Information users
Horizontal - information flow across departments
Vertical - information needs of clerical staff, middle management, and senior executives
Business users
Information users
Management users
Executive users
External users
Client stakeholders
Technical stakeholders

20. Techniques for Information Gathering
Objective of analysis phase is to understand business functions and develop requirements
Original approach involved modeling of existing system
Current approach involves identifying logical requirements for new system

21. Information Gathering and Model Building
Figure 4-5

22. Themes for Information-Gathering Questions
Figure 4-6

23. Fact Finding Methods
Review existing reports, forms, and procedure descriptions
Conduct interviews and discussion with users
Observe and document business processes
Build prototypes
Distribute and collect questionnaires
Conduct JAD sessions
Research vendor solutions

24. Review Existing Reports, Forms, and Procedure Descriptions
First technique in fact-finding
Purposes
Preliminary understanding of processes
Guidelines / visual cues to guide interviews
Identify business rules, discrepancies, and redundancies
Be cautious of outdated material

25. Conduct Interviews and Discussions with Users
Most effective way to understand business functions and rules
Time-consuming and resource-expensive
May require multiple sessions

26. Sample Interview Checklist Figure 4-8

27. Observe and Document Business Processes
From office walkthrough to performing actual tasks
May make users nervous
Not necessary to observe all processes at same level of detail
May be documented with workflow diagrams

28. Characteristics of Prototypes
Preliminary working model of a larger system
Operative
Working model
Focused
Accomplishes single objective
Quick
Can be built and modified rapidly

29. Distribute and Collect Questionnaires
Limited and specific information from a large number of stakeholders
Preliminary insight
Not well suited for gathering detailed information
Open-ended questions vs. close-ended questions

30. Validating Requirements
Make sure gathered information is correct
Structured walkthrough
Effective means of implementing quality control early in project
Verify and validate system requirements
Review of findings from investigation and of models based on findings

31. Evaluating the options for an IS (making the decision)

32. Business System Options
Take a fresh creative view of the required system
Base options on the Requirements Catalogue
Select best options for presentation to the user
two suggested for small projects
six suggested for large projects
Express as narrative
Supported as required with DFDs and LDS
users pick one (or a combination) option
User selection promotes their ownership of the system

33. Business System Options
Project Initiation Document
Logical DFM
Requirements Catalogue
Stage 2
Business
System
Options
Define BSOs
2 - 6 BSOs each containing:
description of functions &
Users
scope
cost benefit analysis
impact analysis
Select BSOs
chosen Business System
Option
Requirements
Specification

34. Range of Options Dramatic options No change option Other possibilities
sack the salesmen and install terminals in customer’s offices
No change option
do nothing and carry on with existing system
Other possibilities
change responsibilities of staff
perform functions in different places
introduce technology to automate functions
eliminate duplication
increase usage of existing information
improve communications between staff
improve communications between company and customers
Position of system boundary

35. Minimal and Advanced Options
Accommodate priorities defined in the Requirements Catalogue
Minimal option
meets the mandatories of Requirements Catalogue
may be an enhancement of current system
Advanced option
meets all requirements
“bells & whistles” solution
high performance

36. BSOs must be easily understood by users
BSO Contents
Narrative describing
functionality of system
business priorities of system and constituent functions
costs and benefits (may include full analysis)
impact on users (organisation, structure, training)
timescales for implementation
any technical considerations affecting business
system boundary and interfaces to other systems (use DFD if appropriate)
BSOs must be easily understood by users

37. Example - Yorkies Option 1 Centralised System
Centralise all the control activities of the company
depots only handle collection and return of vehicles.
Head office handles all bookings and invoicing.
Drivers administered centrally
each driver only serves a group of nearby depots.
Close local offices
Post computer generated forms to customer/depot to confirm bookings
depots informed by telephone of changes
Mileage covered by the customer written on the booking form returned by depot to head office.
Depots inform head office of any vehicles out of service by telephone.
System requires a mini computer and approximately 35 terminals.

38. Centralised System DFD
Booking
Confirmation
Make
Booking
Depot
Completed
Bookings
Booking
Details
Maintain
Vehicle
Records
Record
Completed
Booking

39. Example - Yorkies Option 2 Local Office Autonomy
Local Office are responsible for their own bookings, drivers, and invoicing
Information held centrally - shared by all offices
Almost all data is entered at the local offices
Customers deal with theirlocal office for both bookings and invoices
Offices can make bookings at other offices if they cannot be satisfied locally
System requirements
mini computer and 55 terminals or PCs (1 per office)
communications hardware and software
about 52 printers (1 per office)

40. Autonomous Local Offices Partial DFD
Customers
Sales
Customer
Customer
Booking
Information
New
Customer
HO/Comp
Customer
Information
LO/Comp
Maintain
Customer Records
LO/Comp
Make Booking
for Own Office
New credit
Receiving
rating
Office
Arrange
One-way Hire
Vehicle
Availability
Finance
Booking
Bookings
Vehicle
Arriving
Booking
Vehicle
Availability at
other offices
Other Local
LO/Comp
Office
Booking
Request Booking
at Nearby Office
Local Offices
Request
Nearby
Local
Office
LO/Comp = Local Office + Computer
HO/Comp = Head Office + Computer

41. Autonomous Local Office DFD
Shows the distributed nature of the system
head office responsible for the Customer Records
local offices responsible for the bookings.
Could draw separate DFDs for head office and local offices.

42. Presentation of Business System Options
Depends on the project:
may need report and formal presentations
or just informal discussions
Prepare presentations
list relative advantages and disadvantages of each option
refer to Requirements Catalogue
Make presentations
Provide justifications for selection
Record and document selection decisions

43. Selection of a Business System Option
Users select one or a combination from the options presented
Record selection and reasons for choices
Full specification will be developed for selected BSO

44. Yorkies Select Option 2 with Elements from other Options
Structure of the company remains the same
No offices will be closed
Information will be stored centrally on a mini computer
Each Local Office will have
a terminal or PC (to be decided at Stage 4)
printing facilities
Head Office will control customer records and invoicing

45. Selected Option (continued)
No terminals will be installed in the Depots
Depots will use printed booking forms originated by adjacent office
Local Offices will
accept bookings for any office
maintain customer records (except financial data)
validate bookings against the customer records.
Drivers will be organised into regional pools
Each driver will be available to any office in his region

46. Summary Take a fresh creative view of the required system
Base options on the Requirements Catalogue
Select two or three options for presentation to the user
Present options as narrative describing functionality, costs, benefits, and organisational impacts
Support presentation with LDS and DFDs if appropriate
Users pick preferred option or combination of options