Logic Requirements

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• Tutorial 7
• Logic Requirements
• (Textbook Chapter 8 Appendix)

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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.

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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 salaryEND IFBEGIN IF IF Employee-Type is
Hourly AND Hours-Worked is lt40 THEN CALCULATE
hourly wage AND PRODUCE Absence
ReportEND IFBEGIN IF IF Employee-Type is
Hourly AND Hours-Worked is 40 THEN
CALCULATE hourly wageEND IFBEGIN IF IF
Employee-Type is Hourly AND Hours-Worked is gt40
THEN CALCULATE hourly wage
AND CALCULATE overtimeEND 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

• Structured English representation for process 5.0

DOACCEPT Inventory-record-idREAD
Inventory-record for Inventory-record-idPRINT
Quantity-in-stock and Inventory-item-name UNTIL
End-of-file
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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 the actual processes. Do they fit with
  what users describe?

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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.

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Ch. 8, Ex. 4 (cont.)
(Main) BEGIN IF IF Purchase-amount is greater
than 15,000.00 THEN PurchasingDepartment
APPROVES RFP DO Bid Process ELSE Purchasing-De
partment APPROVES Purchase PURCHASE
equipment END IF (Bid Process) SEND RFP BEGIN
IF IF three Proposals received AND
Winning-Vendor is APPROVED by Purchasing-Departmen
t AND no Violations THEN AWARD contract
PURCHASE equipment ELSE DO Rebid
Process END IF RETURN
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Ch. 8, Ex. 4 (cont.)
(Rebid Process) SEND RFP BEGIN IF IF
Winning-Vendor is APPROVED by Purchasing-Departmen
t AND no Violations THEN AWARD contract
PURCHASE equipment END IF ISSUE Purchase
Order RETURN
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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?

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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

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Part 2 Seq. Activity Diagrams

• The Hire Employee use case / scenario

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• Assume there is only one scenario within the use
  case.
• On receipt of a job application, the applicant
  data is entered through the application entry
  window
• The manager opens the app review window and
  reviews the application
• If the initial review is negative, the manager
  discards the app and conveys the rejection
  decision to applicant
• 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
• The manager interviews the candidate and enters
  the info the application file
• 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
• 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 externalactor

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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(No Transcript)
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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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Level-0 data flow diagram for the PVF WebStore
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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.