Tutorial 7
Logic Requirements
(Textbook Chapter 8 & Appendix)
Tutorial 7
© 2008 Prentice Hall, Ovidiu Noran
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Learning Objectives

Practice Logic Modelling - Structured English and
decision tables to representing steps in logical
processes in DFDs and choice in conditional
statements

Practice Sequence Diagrams

Practice Activity Diagrams

Understand how logic modeling techniques apply
to the development of electronic commerce
applications.
Tutorial 7
© 2008 Prentice Hall, Ovidiu Noran
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Part 1: Decision Logic
Ch. 8, Ex. 1:

Represent the decision logic below in Structured
English
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Ch. 8, Ex. 1 (cont.):

Possible solution:
BEGIN IF
IF Employee-Type is Salary
THEN PAY base salary
END IF
BEGIN IF
IF Employee-Type is Hourly AND Hours-Worked is <40
THEN CALCULATE hourly wage
AND PRODUCE Absence Report
END IF
BEGIN IF
IF Employee-Type is Hourly AND Hours-Worked is 40
THEN CALCULATE hourly wage
END IF
BEGIN IF
IF Employee-Type is Hourly AND Hours-Worked is >40
THEN CALCULATE hourly wage
AND CALCULATE overtime
END
IF
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Ch. 8, Ex. 2 (part):

Generate Structured English and Decision table
logic modelling for some processes described in
the DFD below
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Ch. 8, Ex. 2 (cont.):

Decision table for process 4.0:
Conditions/Courses of Action
Due Status
Generate Rush Payment
Generate Payment
Postpone Payment
1
L
Rules
2
D
3
N
X
X
X
Due status:
L = Late; Date of invoice is more than 30 days before today's date.
D = Due; Date of invoice is 30 days before today's date.
N = Not due: Date of invoice is less than 30 days before today's date.

Structured English representation for process 5.0:
DO
ACCEPT Inventory-record-id
READ Inventory-record for Inventory-record-id
PRINT Quantity-in-stock and Inventory-item-name
UNTIL End-of-file
Tutorial 7
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Ch. 8, Ex. 3:

What types of questions need to be asked during reqs.
determination to gather the logic modelling information?

Start with the processes represented in the DFDs.

Elicit information from users that will help model the logic within
these processes and the events that initiate each process.

Determine the process decision and temporal logic involved in the
users' business processes. Ask the users to literally describe what
happens in each of the processes on the data flow diagrams.





when does the process occur?
what are the explicit steps?
how and by whom are they performed?
in what sequence and at what time are they performed?
are there any conditions, constraints, or contingencies on any of these
steps happening? If so, what are they and how do they happen?

Observe
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the actual processes.
Do they fit with what users describe?7
© 2008 Prentice Hall, Ovidiu Noran
Ch. 8, Ex. 4:

Use Structured English to represent the logic in the
following narrative:

In a company the rules for buying perosnal computers are such that if
the purchase is over $15,000 it has to go out for bid and the Request
for Proposals must be approved by the Purchasing Department. If the
purchase is under $15,000, the personal computers can simply be
bought from an approved vendor; however, the Purchase order must
still be approved by the Purchasing department. If the purchase goes
out for bid, there must be at least three proposals received for the bid.
If not, the RFP must go out again. If still there are not enough
proposals, the process can continue with the vendors that have
submitted proposals. The winner of the bid must be on an approved
list of vendors for the company and, in addition, must not have any
violations against them for e.g. environmental matters. At this point, if
the proposal is complete, the Purchasing Department can issue a
Purchase Order.
Tutorial 7
© 2008 Prentice Hall, Ovidiu Noran
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Ch. 8, Ex. 4 (cont.):
(Main)
BEGIN IF
IF Purchase-amount is greater than $15,000.00
THEN
Purchasing–Department APPROVES RFP
DO Bid Process
ELSE
Purchasing-Department APPROVES Purchase
PURCHASE equipment
END IF
(Bid Process)
SEND RFP
BEGIN IF
IF three Proposals received
AND Winning-Vendor is APPROVED by Purchasing-Department
AND no Violations
THEN AWARD contract
PURCHASE equipment
ELSE DO Rebid Process
END IF
RETURN
Tutorial 7
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Ch. 8, Ex. 4 (cont.)
(Rebid Process)
SEND RFP
BEGIN IF
IF Winning-Vendor is APPROVED by Purchasing-Department
AND no Violations
THEN AWARD contract
PURCHASE equipment
END IF
ISSUE Purchase Order
RETURN
Tutorial 7
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Ch. 8, Ex. 6

Present the logic of business processes described in the
previous exercise in a decision table. How do decision
tables compare with Structured English for this example?
Conditions/Courses of
Action
Purchase Amount
Vendor Approved
Rules
1
G
Y
2
L
Y
3
G
N
4
L
N
Award Contract to
X
Winning Vendor
Issue Purchase Order
X
X
Purchase Equipment
X
X
Award Contract to Other
X
Approved Vendor
Find Another Approved
X
Vendor
Purchase Amount: G = greater than $15,000.00,
L = less than or equal to $15,000.00
Vendor Approved: Y = Yes; approved by Purchasing Department
N = No; not approved by Purchasing Department
Tutorial 7
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Ch. 8, Ex. 6 (cont.)

How do decision tables compare with Structured English
for this example?

Several fairly complicated conditions are present hence
the Structured English approach may be better. Several
decision tables could be used as well.

Again, the decision tables are good at reviewing /
optimising the decision logic but not at determining
conditions and actions or at transforming conditions and
actions into sequence
Tutorial 7
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Part 2: Seq. & Activity Diagrams

Tutorial 7
The Hire Employee use case / scenario
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
Tutorial 7
Assume there is only one scenario within
the use case.
1.
On receipt of a job application, the applicant data is entered through
the application entry window
2.
The manager opens the app review window and reviews the
application
3.
If the initial review is negative, the manager discards the app and
conveys the rejection decision to applicant
4.
If initial review is positive, the manager sets up a date and time to
interview the applicant. The manager also requests that the referees
specified in the app provide recommendation letters
5.
The manager interviews the candidate and enters the info the
application file
6.
When the recommendation letters come in, the manager is ready to
make a decision. Based on the summary, a decision is made. If the
decision is to reject, the application is discarded and the applicant is
notified. The processing of the application comes to an end
7.
If the decision is to hire the candidate, a potential employee file is
created and all relevant info is entered into this file. The hiring decision
is conveyed to applicant.
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Sequence Diagram for Hire Employee
Decision logic
:
Explicitly
shown
external
actor
Decision logic
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Ch. 8 App, Ex. 4

Draw an activity diagram for the previous employee
hiring process.
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Human
Resources
Department
Manager
Enter applicant
data
Review
application
-ve
+ve
Ask for
references
Set up
Interview
Hold
interview
Produce
Summary
accept
reject
Create
potential
employee file
Send
outcome to
applicant
Tutorial 7
© 2008 Prentice Hall, Ovidiu Noran
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Part 3
Case Study: Pine Valley Furniture (PVF)

Manufactures high-quality wood furniture

Distributes to retail stores within the U.S.

Started in the early 1980s and expanded by
1984 doubling sales volume

By 1990, Pine Valley Furniture had become a
complex company, employing over 50 persons
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PVF: Logic Modelling
Pine Valley Furniture development
methodology dictated that the logic within
each unique processes be represented.
 Structured English was chosen for
modelling the logic.

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Tutorial 7
Level-0 data flow
diagram
for
theNoran
PVF WebStore
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Prentice Hall,
Ovidiu
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PVF: Logic Modelling
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E-commerce App: Logic Modelling
Process 3 decomposition DFD for the PVF WebStore
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E-commerce App: Logic Modelling
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E-commerce App: Logic Modelling
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Summary

In this tutorial you practiced:

Logic Modelling - Structured English and decision
tables

Sequence Diagrams

Activity Diagrams

Logic modelling techniques applied to the
development of electronic commerce applications.
Tutorial 7
© 2008 Prentice Hall, Ovidiu Noran
25