1. REQUIREMENTS ANALYSIS
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2. Context of System Analysis

3. Requirements Analysis
One of the early IS development phases.
ERD: part of requirements analysis phase
The process and technique that a group of system analyst uses to identify, analyze, and understand system requirements
System’s requirements specify what the information system must do, or what property or quality the system must have.
What do bank tellers need and want from the new or renovated system?
Critical phase for reducing the system cost
No additional notes.

4. Requirements Analysis for RDS
Identify essential information
Remove redundant, unimportant details
Clarify unclear natural language statements
Distinguish data and operations
Data: ERD (entity relationship diagram)
Operation: DFD (data flow diagram)
Example: Movie Video Rental (next slide)

5. Example: Movie Video Rental
MovieClub is a video rental store that has a variety of films for every age group. The manager of the club has a database application installed to manage the store more efficiently. The database application supports the main business operations in the store, namely, video checkout and return, inventory management, and membership management. It is also used to answer possible customer queries about the availability of certain films. The following is a description of the conceptual model of the video rental database at MovieClub.
 The video rental database contains information about members, films, video tapes, and rentals. The information on members includes the name, address, phone number, and the expiration date of the membership. A member is identified with a unique membership number.

6. Example con’t
Films have identification numbers and are described by title, length (in minutes), category (drama, comedy, action, sci-fi, etc.), version (English, French, Spanish), and production date. There are usually several video tapes of each film. Every video tape is identified by a unique tape identification. Other information kept in the database about the tape includes type (VHS or DVD), and the rate at which in can be rented.
A member can rent several video tapes at the same time. Obviously, the same video tape can be rented by several members on different dates. Tape rental information, represented in the database, consists of checkout date, and duration (in days). It is important to notice that the same video tape can be rented by the same member more than once.

7. Essential information
ƒcustomers, tapes, movies, ...
ƒmovies have many copies
tape (or DVD) contains exactly one movie
several video tapes of each film
identification (id)

8. Redundant, unimportant details
….”manager of the club has a database application installed to manage the store more efficiently….” (unimportant)
..”same video tape can be rented by several members..” (redundant)
A member can rent several video tapes at the same time.
DVDs on shelf (we do not design a tape robot!)
Names of the categories (maybe not now! But later)

9. Relative Cost to Fix an Error

10. Relative Cost to Fix an Error (BASED ON CONSULTANT REPORTS & TRADE LITERATURE)1 2 3 4 5
COSTS
ANALYSIS AND DESIGN
PROGRAMMING
CONVERSION
POSTIMPLELENTATION

11. Results of Incorrect Requirements Analysis
The system may cost more than projected
The system may be delivered later than promised.
The system may not meet the users’ expectations and that dissatisfaction may cause them not to use it.
Once in production, the costs of maintaining and enhancing the system may be excessively high.
No additional notes.

12. Very Difficult to Manage
Over the lifetime of the project, it is very common for new requirements to emerge and existing requirements to change.
Studies have shown that over the life of a project as much as 50 percent or more of the requirements will change before the system is put into production.

13. Fact-Finding Technique
Sampling of existing documentation, forms, and databases.
Research and site visits.
Observation of the work environment.
Questionnaires.
Interviews.
Prototyping.
Joint requirements planning (JRP).

14. System Development Documentation
Data model becomes an official blue print (system document) of the DB
Department of Justice
See the Department of Justice documentation on the course website
System development is about “documentation….. Documentation…… documentation”

15. IS Architecture Can be divided into data and process architectures
Data architecture by Data Model
ERD: focus on the optimal organization of data, not on where or how data are used
Process architecture by Process Model
DFD (Data Flow Diagram): focus on how and when data are moved
Diagram for IS architecture
UCD (Use Case Diagram)

16. What is Use Case Diagram?
The UCD is for the modeling of real-world objects and systems.
It is a graphic depiction of the interactions between stakeholders and a system
Focus on “What a system does”…”rather than how a system does.”
In other words, it is a methodology used in system analysis to identify, clarify, and organize OVERALL SYSTEM REQUIREMENTS.

17. UCD for Bank ATM
Chapter 7 - Modeling System Requirements With Use Cases

18. Creating Data Flow Diagram Lemonade Stand Example

19. Creating Data Flow Diagrams
Example
Steps:
The operations of a simple lemonade stand will be used to demonstrate the creation of data flow diagram.
Create a list of activities
Construct Context Level DFD (identifies sources and sink)
Construct Level 0 DFD (identifies manageable sub processes )
Construct Level 1- n DFD (identifies actual data flows and data stores )

20. Creating Data Flow Diagrams
Example
Create a list of activities
Think through the activities that take place at a lemonade stand.
Customer Order
Serve Product
Collect Payment
Produce Product
Store Product
Order Raw Materials
Pay for Raw Materials
Pay for Labor

21. Creating Data Flow Diagrams
Example
Construct Context Level DFD (identifies sources and sink)
Create a context level diagram identifying the sources and sinks (users).
Context Level DFD
Sales Forecast
CUSTOMER
0.0
Lemonade System
EMPLOYEE
Order
Production Schedule
Customer Order
Serve Product
Collect Payment
Produce Product
Store Product
Order Raw Materials
Pay for Raw Materials
Pay for Labor
Product Served
Pay
Payment
Time Worked
Received Goods
Payment
Purchase Order
VENDOR

22. Creating Data Flow Diagrams
Example
Construct Level 0 DFD (identifies manageable sub processes )
Create a level 0 diagram identifying the logical subsystems that may exist.
Level 0 DFD
1.0
Sale
Sales Forecast
Customer Order
Serve Product
Collect Payment
Produce Product
Store Product
Order Raw Materials
Pay for Raw Materials
Pay for Labor
Customer Order
Product Ordered
CUSTOMER
Payment
2.0
Production
EMPLOYEE
Production Schedule
Product Served
Inventory
Received Goods
VENDOR
3.0
Procure-ment
Purchase Order
Order Decisions
Payment
Pay
Time Worked
4.0
Payroll

23. Creating Data Flow Diagrams
Example
Construct Level 1- n DFD (identifies actual data flows and data stores )
Create a level 1 decomposing the processes in level 0 and identifying data stores.
Level 1 DFD
CUSTOMER
Customer Order
Request for Forecast
Customer Order
Serve Product
Collect Payment
Produce Product
Store Product
Order Raw Materials
Pay for Raw Materials
Pay for Labor
ORDER
1.1
Record Order
1.3
Produce Sales Forecast
Severed Order
Payment
Sales Forecast
1.2
Receive Payment
PAYMENT

24. Process Decomposition
1.0
Sale
1.1
Record Order
1.2
Receive Payment
2.0
Production
2.1
Serve Product
2.2
Produce Product
2.3
Store
Product
0.0
Lemonade System
3.0
Procure-ment
3.1
Produce Purchase Order
3.2
Receive Items
3.3
Pay Vendor
4.0
Payroll
4.1
Record Time Worked
4.2
Calculate Payroll
4.3
Pay Employee
Context Level
Level 0
Level 1

25. Why not using Flow Chart?
Complex Logic:
Many of today’s IS program logic is quite complicated. In that case, flowchart becomes complex and clumsy because the complexity can grow exponentially.
Not so recommendable in MIS & CS
Alterations and Modifications:
If alterations are required the flowchart may require re-drawing completely. This is quite time and effort-consuming.

26. Why not using Flow Chart?
Reproduction:
As the flowchart symbols cannot be typed, reproduction of flowchart becomes a problem.
The essentials of what is done can easily be lost in the technical details of how it is done.
Factors that affect the sequence are not included.

27. How to develop IS Architecture?
How the foundation of IS architecture should be developed?
IS architecture
IS Strategy
Corporate Strategy
Strategic Management
Mission statement: root of strategic Mngt.

28. Strategic Management Highest level of overall planning
is the continuous planning, monitoring, analysis and assessment of all that is necessary for an organization to meet its goals & objectives and to position a firm to succeed in its market environment.

29. Strategic Management Process (con’t)
Components of Strategic Management Process
Strategic Management Process (4:35)
Website: Strategic Management Process