1. Chapter 9 - Multimedia
IDCS - Computer Technology

2. Programming Methods (CT)
Chapter 9 - Multimedia
Programming Methods (CT)
Chapter 3 SECTION B DATA ANALYSIS AND PROBLEMS
IDCS - Computer Technology 3

3. Chapter CONTENTS: Analyzing problems
Designing a top-down modular program
Determining the structure of a programm from a given specification
Structured Programming diagrams
CRC cards

4. Chapter 3 SECTION B Data Analysis and Problems
Chapter 9 - Multimedia
Chapter 3 SECTION B Data Analysis and Problems
PART 1 Analyzing the Problem
IDCS - Computer Technology 3

5. 1.1 Analysing the Problem Insist on a proper program specification
Analyse the problem
Break down the problem down
E.g. how to fix/change a flat tire

6. Example : Hospital Information System Module and Sub-modules
Chapter 9 - Multimedia
Example : Hospital Information System Module and Sub-modules
Hospital information System
Personnel DB
(Nurses, Doctors, etc)
Patients DB
(Emergency, OPD, etc)
Transaction DB
(Doctors + Patient, Payments)
Inventory DB
(Drugs, Medical Equipments)
IDCS - Computer Technology 3

7. 1.3 Definitions of Key Terms
 Top-down Development
An approach to program development in which is made by:
defining required elements in terms of basic elements
beginning with the required program and ending when implementation language is reached
At every stage during the top-down development, each of the undefined elements from the previous stage is defined.
Stepwise refinement (enhancement)
An approach to software development in which an initial, highly abstract representation of a required program is gradually refined through a sequence of intermediate representations.

8. 1.3 Definitions of Key Terms (cont)
 Program Decomposition
The breaking down of a complete program into a set of component parts called modules.
E.g. Visual Basic Procedures
Modular Programming
A style of programming in which complete program is decomposed into a set of components (called modules)
E.g. VB Module (illustrate)
manageable size
has well defined purpose
has a well defined interface for use by other modules

9. 1.4 Designing a Top-down Modular Program
One module contains the instructions that supply the top-down logic for the whole program
This module contains the three basic functions:
Initilialising
Processing
Closing down the program

10. 1.5 Examples of Initialization Routines
Requesting library routines
E.g. include <stdio.h> (C Language)
Opening file
Defining headings, creating opening screen
Initialising variables
E.g. Dim x as Integer, name as String (VB Language)

11. 1.6 Examples of Processing Tasks
Input
reading records from a file
requesting data from the user
Computation and logic
comparing values
computations
assignments
Output
updating files
writing records to a file
printing a report
displaying information on screen

12. 1.7 Examples of Closing Tasks
Producing printed output
Writing a file
Printing final totals in a report
Displaying final user messages
Closing all open files

13. 1.8 Jackson Structured Programming (JSP) - Iteration
Hierarchical diagrams can be used to illustrate a method of problem solving.
But there must be way (for these diagram to be useful) of showing sequence, selection and iteration
NOTE:
JSP addresses the these different requirements:
Reading records from a file
Processing the element of an array
Repeating procedures from a lower level in the diagram

14. 1.9 Jackson Structured Programming - Iteration

15. 1.10 Jackson Structured Programming (JSP)- Example 1
NOTE:
Reading records until the End of File (EOF)
Illustrate VB program example

16. 1.11 Jackson Structured Programming (JSP)- Example 2
NOTE:
Continue processing until user types stop.

17. 1.12 Jackson Structured Programming (JSP)
You must also make a selection of such
tasks such as:
Choosing an alternative procedure at a lower level
Taking actions according to the results of the entries
Making comparisons and acting on the result
NOTE:
In this technique is to write the conditions above or below each box to be chosen results of the selection and insert an ‘0’ in the top right corner of the box.

18. 1.12 Jackson Structured Programming (JSP)- Example 3
NOTE:
Jackson Structure Diagram showing convention for selection
Illustrate VB program example

19. 1.13 Determining the Structure of a Program
Program is designed from the program specification
SCENARIO: Assessment Results
Program is to read a file of records of a students name
Six examination marks (integer value)
Calculate average mark
Assessed grade
FAIL, which is >39 and <=39
PASS, which is >39 and <=59
MERIT, which is >59 and ,<79
DISTINCTION, which is >79
Result to be written on new file
Each record should contain
name, average, percentage mark and grade
On termination print students whom examination marks have been processed

20. 1.13 Determining the Structure of a Program (cont.)
The program can be separated into components initialization tasks, processing tasks and closing tasks.

21. 1.14 Stepwise Refinement – Step 1
Outline requirements for each component
STEP 1:
Initialising : Open files
Processing : Process each record to find grades
Closing : Close files

22. 1.15 Stepwise Refinement – Step 2
They can be further divided to give each of the following refinements
STEP 2:
Initialising refinement : open file for reading and writing
Processing refinement : set up lop to read in and process each record
Closing refinement: close files, output closing message

23. 1.16 Stepwise Refinement – Step 3
No further refinement needed for initialisation or termination
Further analysis of the processing tasks is needed
STEP 3: Processing of the records
calculate the mean
establish the grade
write the results to a file
count the number of records

24. 1.16 Stepwise Refinement – Step 3 (cont.)

25. 1.16 Stepwise Refinement – Step 4
Actions required to complete the diagram are easily determined
Calculate average
Accumulate marks
Divide the total number of marks (6)
Assign result average variable
Assess grade
Compare average with grade boundaries
Write result to grade variable
Write to file
Write name variable + average mark + grade variable record
Accumulate number of records
Make sure this running total is at zero ate the beginning of the program

26. 1.17 Jackson Structured Programming
This technique
Uses a top-down stepwise refinement
Uses only three control structures
Bases the program design on the structure of the data to be processed
The steps are:
From the program specification, produce data structure diagrams of the data to be input for the processing and output
Produce a program structure which reflects the requirements of the data structures
Analyse this in a top-down manner to produce a more increasingly more specific program structure.

27. 1.18 JSP Example 1 – Physical Data Structure
NOTE:
A stock record is organized into sections by content (children's clothes, men's clothes, and women’s clothes). The data on children's clothes is to be extracted

28. 1.19 JSP Example 1 – Logical Data Structure
NOTE:
The logical data structure reflects that no processing.

29. 1.20 JSP Example 2 – Physical Data Structure
NOTE: Physical data structure diagram of transaction file
A transaction file has been created by inputting the information on sales and purchases in batches.
Each batch has a header record followed by records with the details of sales and purchases.
The batches of records are input as they are received and therefore can occur in any order.

30. 1.21 JSP Example 2 – Logical Data Structure
NOTE: Logical data structure diagram of transaction file
If sales report is required (no reference to purchases) which shows totals for both cash and credit sales as shown above.
Every record will no longer be processes and the purchases will be ignored.

31. 1.22 Establishing the Program Structure
Criteria:
Determine the input and output data structures
The output requirements are a great help in determining the logical structure of a file.
Combining them to produce the program structure
The example is process is illustrated is on the next slide

32. Physical and Logical DSDs
1.23 Example 1 : Using One Input File to Produce One Output File or Report
Physical and Logical DSDs

33. 1.24 Example 1 : Continued.. Physical DSD - Report NOTE:
The report structure is to have a heading, a on-line summary of the total order value for each garage, and a footer containing the total of all orders.

34. Comparison of Physical DSDs
1.25 Example 1 : Continued..
Comparison of Physical DSDs

35. DSDs of Input and Output
1.26 Example 1 : Continued..
Comparison of Logical
DSDs of Input and Output

36. 1.27 Comparison of Logical DSDs of Input and Output (cont.)
Explanation of Previous Slide
The output requirement does not need to include the area of each garage
The logical DSD of the input files, do not need to include this component.

37. 1.28 Program Structure NOTE: PSD Properties
Each data component is related only to one program component.
Each program component is related only to one input and/or one out component.

38. Chapter 3 Data Analysis and Problems
Chapter 9 - Multimedia
Chapter 3 Data Analysis and Problems
PART 2 CRC Diagrams
IDCS - Computer Technology 3

39. 2.1 What are CRC Cards? CRC Cards stands for:
Class
Responsibility
Collaboration
Created in the late 1980s as a method to teach object oriented paradigm

40. 2.2 What are CRC Cards? (cont..)
CRC cards aimed to find a way to express a system in an abstract way that was analogous to structured programming.
CRC cards are brainstorming tool used when first determining which classes are needed and how they will interact.

41. 2.3 Advantages of CRC Based Modelling
There are many advantages in using a CRC-
based modelling
Creates a good understanding of the domain to be modelled
It identifies high level of responsibilities
It ensures better system design
It ensures that knowledge of the domain is shared by anyone
A good working can be developed
It is a good way to identify areas that maybe missed otherwise
It is a fun

42. 2.4 CRC Finding Classes and Considering Scenarios
Participants need to know what the requirements of the system will be
Brainstorming
the major classes for the system are identified
Individual classes can then be discussed and refined until a set is agreed
The group then considers scenarios likely to occur, to test the classes some will be discarded, others will become subclasses
A subclass is a class within a class
sharing some of the attributes and behaviors of its parent, but having attributes and behaviors of its own

43. 2.5 CRC Method
A CRC card session should involve about five or six people
include people who have a detailed understanding of the system to be developed
Begin with a brainstorming session
usually someone oversees the session, recording suggestions on a flipchart/board
these suggestions form the basis of the classes for the system
Next, the classes suggested are discussed in detail and some will be filtered out

44. 2.6 CRC Method (cont.)
Each class is written on a card, and assigned to a participant
a short description can be added on the back of the card, which can be read out to the group for approval
Next, the group considers simple scenarios which are likely to occur
helps to discover any missing classes, and the relationships that objects have to each other
Scenarios involve a discussion of how the classes behave and how they interact with each other

45. Chapter SUMMARY In this Chapter we have covered:
Program development process
Structure diagrams
Organizing information
Fixed and variable length record
Analyzing the problem
Structured programming diagrams
CRC cards introduction including scenarios, role play and method
FINAL NOTE:
To facilitate better understanding of all of these methods, techniques and methodologies, you are advised to work through the Self Study Section and Exercises at the end each Chapter on your Textbook.