1. Higher Software Development

2. Core Text
How to pass Higher Computing
Chapter 2 – pages

3. What you should already know
There are 7 stages in software development A
D I T D E M
Analysis
Design
Implementation Testing Documentation Evaluation Maintenance
A day in town drives everyone mad

4. What you will learn in Unit 1
Section 1 – The software Development Process
Section 2 – Development Languages and Environments
Section 3 – High Level Language Constructs
Section 4 – Standard Algorithms

5. Software Development – Topic 1
The Software Development Process

6. What this unit will cover – Learning Outcomes
Understand the iterative nature of the software development process
Understand each stage of software development

7. Iteration
Each stage in the SDP makes a contribution to the final product
The stages are carried out in order but stages may be revisited if a problem occurs
This is called iteration
Iteration can occur at any time in the software development process

8. GLOSSARY DEFINITIONS Define Iterative
At the back of your jotter write a glossary definition of the word iterative as it relates to the SDP (page 44)
Write down an acronym of your own to help you remember the 7 stages of the software development process

9. Documentation used throughout SDP
Software specification – a legally binding contract defining the scope and boundaries of the project.
Algorithm - A description of how the problem will be solved
Structured Listing – A formatted printout of the program code
Test Report – A list of test data with expected and actual output from the program

10. User Guide – A set of instructions on how to install and use the software
Technical Guide – Description of the technical requirement to run the program (RAM, OS, Disk Space, etc)
Evaluation Report – A report which accompanies the software and comments on the original specification
Maintenance Report – Details the maintenance that has been carried out

11. Personnel involved in the SDP
1. Client
2. Systems Analyst
3. Project Manager
4. Programmer
5. Independent test group

12. Client Someone who buys or intends to buy the software
Client defines the scope and boundaries of the project

13. Systems Analyst
Carries out initial investigation (could be a team of analysts for a large system)
The Analysts role is broken down into:-
Collecting information
Analysis information collected
Producing a requirements specification

14. Project Manager Responsible for the supervision of the project.
Main tasks are to keep the project on schedule and within budget (within scope and boundaries)

15. Programming Team Responsible for the coding part of the development
Work to design created by analysis and design teams
Also responsible for testing and maintenance
In large projects a team of programmers will work together

16. Independent Test Group
The software is passed to independent test groups for impartial testing
This may include
Alpha testing – in-house personnel
Beta testing – selected users outside the company

17. Written Task Link to Table
Using the information on pages 44 and 45 complete the following table – use your own words – do not copy the table on page 45 word for word!!!
Stage
What happens at this stage
Personnel Involved
Documentation (with description)
Analysis
Scope and boundaries of the problem are discussed and agreed
Client, Systems Analyst
Software Specification - a legally binding contract defining the scope and boundaries of the project

18. Analysis

19. What is analysis?
Analysis is an attempt to understand a given problem, clearly and exactly, and to generate a specification.
Full systems analysis has three phases:
collection of information
analysis of information collected
production of a software specification

20. Extracting the Clients needs
Also known as requirements elicitation
This is done by the Systems analyst by:
interviewing the clients
completing questionnaires
making observation notes
inspecting existing systems and documentation
Scope and boundaries of project must be agreed – eg money and time constraints

21. GLOSSARY
At the back of your software development jotter write a glossary definition of the following terms:-
Software Specification
Systems Analyst
Project Manager
Client
Programmer
Independent Test Group

22. Past Paper Question Analysis
Look at the structure of the Higher Computing Paper. Your glossary definitions must be memorised in such a way as to allow you to answer these sorts of questions
2001 – Q11
2002 – Q7, 8
2003 – Q2
2004 – Q11

23. Complete these Past Paper Questions on analysis in your jotter
What is meant by the term iterative during the software development process? Use an example of iteration during the SDP to explain your answer marks
What is the purpose of the analysis stage?
1 mark
Describe two techniques used by a Systems Analyst in the analysis stage of the software development process.
2 marks

24. Checkup on Analysis

25. Design

26. Designing the Solution
Once the software specification has been agreed by the client and the systems analyst the design begins
Design can be text based – pseudocode or graphical based – flow chart, structured diagram
Each of method involves taking a big problem and breaking it down into smaller sections

27. Top Down or Bottom Up TOP DOWN DESIGN WITH STEPWISE REFINEMENTS
Taking a big problem and breaking it down into smaller and smaller parts
BOTTOM UP DESIGN
Looking at bits of the problem which have already been solved and build from this

28. Top Down Design Example

29. Pseudocode Text method of designing a program
Uses a mixture of english words and programming terms
Uses a systematic numbering system
Top-level algorithm
(List of main steps)
Refinements
(How you achieve each main step)

30. Example of pseudocode that you will use later on in the course
1. set counter to zero
2. prompt user to input search value
3. set pointer to start of list
4. do
4.1 compare search value to item at current list position
4.1.1 if search value = current item then
4.1.2 increment counter by 1
4.1.3 set pointer to next position in the list
4.2 loop until end of list
5. output number of occurrences (counter)

31. EXAMPLE – Pseudocode - Top Level Algorithm
Top-level algorithm for a program to calculate a persons wage:
Find out persons details
Calculate wage
Display wage
What details will you need to enable you to calculate and display someone’s wage?

32. EXAMPLE – Stepwise Refinements
These are the refinements for step 1 of the program which will calculate a persons wage:
1.1 ask for name
1.2 ask for rate
1.3 ask for number of hours

33. COMPLETE ALGORITHM WRITTEN IN PSEUDOCODE
Find out persons details
1.1 ask for name
1.2 ask for rate
1.3 ask for number of hours
Calculate wage
wage = rate * number of hours
Display wage

34. For you to do
Using the example on the previous slide write algorithms for the following programs:-
Calculate and display the area of a rectangle
The computer stores a number – ask the user to input a number and compare them. Display an appropriate message depending on whether the guess matches the number stored.

35. Algorithm to Calculate the area of a rectangle – suggested solution
Find out measurements
1.1 ask for length
1.2 ask for breadth
Calculate area
1.1 area = length * breadth
Display area

36. Compare guess and display message
Algorithm to Store a number, get an input, compare results and display message
Store the lucky number
Get the users guess
Compare guess and display message
3.1 If guess = lucky number
Display well done message
3.2 Else
Display bad luck message

37. Structured Chart/ Structured Diagram
A structure chart gives a picture of the program design
Styles vary but all contain boxes, lines, arrows and text
Structure charts are read from top to bottom.
A structure chart shows the relationship between different parts of the program

38. Example to breaking a problem down using a structured chart

39. STRUCTURED CHART ENTER RATE No OF HOURS WAGE = RATE * No OF HOURS
CALCULATE
WAGE
DISPLAY
CALCULATE A PERSONS WAGE
FIND OUT
PERSONS DETAILS
ENTER
NAME

40. Flow Chart
A method which uses a series of shapes with connecting arrows to show the design of a program
It also shows the flow of data throughout the program

41. FLOW CHART START FIND OUT NAME FIND OUT RATE FIND OUT NUMBER OF HOURS
WAGES = RATE * NUMBER OF HOURS
DISPLAY WAGE
STOP

42. Glossary Definitions
At the back of your jotter write a glossary definition of each of the following
Pseudocode
Structured Diagram
Flow Chart
Top Down Design
Bottom Up Design

43. Complete these past paper questions in your jotter
The first two stages of the software development process are analysis and design - state the purpose of each of these stages marks
Describe the design methodology known as Top Down Design with Stepwise Refinements marks
Describe one graphical design notation used during the design stage (you may use a diagram) marks

44. Match Up
Complete the Match Up Exercise on Analysis and Design

45. Implementation

46. Implementation
Programmers translate the design into a form the computer can understand ie program code

47. Choice of Programming Language
Other than programmers experience the following are taken into account when choosing which programming language to implement the program
Nature of the problem
Hardware and software compatibility
Data types
Features of the language

48. Testing

49. Purpose of Testing Testing should be systematic and comprehensive.
Testing cannot always be exhaustive.
What do you understand by these statements?

50. Testing
Systematic - A logical approach ensuring errors are documented, corrected and then testing is repeated
Comprehensive – all possible situations, inputs and operations will be tested
Exhaustive - In the real world it is difficult to test for every possible input which means no matter how exhaustive testing is, it is rarely 100% conclusive

51. Test Data TESTING NORMAL EXCEPTIONAL EXTREME CONDITIONS CONDITIONS

52. Test Data should cover NORMAL – within the expected range
EXTREME – testing at the boundaries or limits of the expected input
EXCEPTIONAL – testing outside the expected limits of the input

53. Who does the testing? The programmers Independent Test Groups
The client
All of the above must be involved in the testing process

54. Testing by programmers
Good for initial testing but unlikely to show up all types of errors as they “know” the software too well
Think of two other reasons why the programmers shouldn’t be the only ones to test their own programmes

55. Independent Test Group
Involves people other than the programmers
Any errors are recorded
Software is returned to programmer to be amended
This is usually called Beta Testing

56. Testing by the client
The client must be allowed to test the software in the environment where it is going to be used
This will often show up errors not uncovered by the programmers or ITG
This is called Acceptance testing

57. Glossary Definitions
At the back of your jotter write a glossary definition for
Systematic testing
Comprehensive testing
Acceptance Testing
Beta Testing
Normal test data
Extreme test data
Exceptional test data

58. Past Paper questions
Suggest a suitable set of test data for a program that will be used to convert the number of a month into the name of the month.
2 marks
A program will ask a user to enter their name and age. Suggest a suitable set of test data to test the variable age.

59. SQA marking scheme
1. Data should include: zero, negative number, integer in range 1-12, integer outwith range, real number, text.
Example of all 3 – 2 marks
Example of 2 – 1 mark
Example of 1 – 0 marks
Do not give a mark for just stating Normal/Extreme/Exceptional

60. SQA marking scheme
2. Data should include: zero, negative number, integer in appropriate range, integer outwith range, real number, text.
Example of all 3 – 2 marks
Example of 2 – 1 mark
Example of 1 – 0 marks
Do not give a mark for just stating Normal/Extreme/Exceptional

61. More Past paper questions
Q. Describe one technique used to ensure the program is robust.
A. Testing with exceptional test data to ensure the program can cope with unexpected inputs without halting.
Q. Explain why 3 types of test data are normally used to test a program
A. Normal, extreme and exceptional data should be used to test correctness, reliability and robustness

62. Types of error found at the testing stage – Logical errors
Mistakes in the design or logic of the program
Program may work but output is not as expected therefore the program is not correct
Counter = 0 DO
counter = counter +1
LOOP UNTIL counter = 0

63. Syntax errors When the rules of the language are broken eg
PINT instead of PRINT, NED instead of END
Missing brackets, colons or semi-colons

64. Glossary definitions
At the back of your jotter write a glossary definition for
Syntax errors
Logical errors

65. Documentation

66. Types of documentation
There are two types of documentation
Documentation for the Software Development Team
Documentation for the end users

67. Documentation for SD Team
The software development team documents each stage of the process. So far we know:-
Analysis Stage:
Software Specification
Design Stage:
Algorithm (Flowcharts/ Structured Diagrams/ Pseudocode)
Implementation Stage:
Internal Commentary
Structured Listing

68. User Documentation
The documents which accompany the finished software product
These documents are made available to the end user of the software
User Guide
Technical Guide

69. The User Guide Describes how to use the program:
How to start up the program
Explains the different commands and how to use them
Usually includes tutorials

70. The Technical Guide How to install the software Memory requirements
Processor requirements
Operating System requirements
Version number of software
Troubleshooting guide

71. Glossary Definition
At the back of your jotter write a glossary definition for
User guide
Technical guide

72. Past Paper Questions
Hillhead Secondary have recently bought new software, when they try to install the software they find that they do not have enough hard disc space. Which part of the software documentation should they have read before installing the software? 1mark
What information would this documentation have told them mark

73. Throughout the software development process it is important that appropriate documentation is created. Name 2 pieces of documentation and the stages they are produced at (do not include documentation produced at the documentation stage) marks
Describe the two guides which must be produced at the documentation stage.
2 marks

74. 5. When developing a piece of software 3 different user interfaces were created. Describe how you could test which one of the interfaces was most suitable for the end user.

75. Suggested SQA Solutions
Technical guide
Would have told them the systems requirements (memory, processor, RAM, OS, etc)
Software Specification, Algorithm (Flowcharts/ Structured Diagrams/ Pseudocode), Structured Listing, Test report, evaluation report, etc
User guide - describes how to use the program, start the program, different commands and how to use them, includes tutorials - Technical guide – Describes the system requirements for the software eg Memory requirements, Processor requirements, Operating System requirements, Version number of software, Troubleshooting guide
Testing each interface with sample users. Use feedback to make final decision - Use Independent Test Group and use feedback from this group

76. Evaluation

77. On-going evaluation
An evaluation is produced and given to the client with the finished software
Each stage of the Software Development Process should be evaluated before moving onto the next stage
It is too late at the evaluation stage to realise that the analysis was incomplete and therefore the program produced only solves half the problem

78. Fit for Purpose
The evaluation report should state that the software is fit for purpose
Fit for purpose means that it does what was outlined in the software specification
In other words the program is correct

79. Does the software meet the specification?
The software should be evaluated against the following criteria
Correct
Reliable
Robust
Efficient
Maintainable
Portable

80. Glossary definitions
Correct/Fit for Purpose - Meets the software specification document
Reliable – Free from design faults and works for all valid inputs
Robust – can cope with errors while running and will not fail when unexpected input is entered or unexpected results are generated

81. Efficient – does not use unnecessary memory or processor time
Portable – Can work on computer system types other than the one it was designed for with little or no adaptation
Maintainable – can be easily updated at a later date by programmer other than those who originally created it

82. What helps makes a program maintainable?
As well as documenting the software a program will be easier to update at a later stage if the code is:-
Readable – uses comments, meaningful variable names and white space
Modular –uses sub routines or functions (is broken up into smaller parts)

83. Glossary definitions
Readable
Modular

84. Past Paper Question on evaluation
Q. Once software has been developed and implemented, evaluation of the product will take place. What criteria should be considered when evaluating software?
2 marks
A. Is the software correct – does is meet the specification document, is it maintainable, portable, efficient, reliable and robust

85. Maintenance

86. Maintenance Activities
Maintenance is making changes to a program once it has been developed
Maintenance starts as soon as the system is delivered to the client
Maintenance is an ongoing process

87. Maintenance Activities
CORRECTIVE
ADAPTIVE
PERFECTIVE

88. Corrective Maintenance
Undetected errors at the testing stage are reported to the developer by the client
This fixes errors not found at the testing stage
The cost of this type of maintenance is met by the software company

89. Adaptive Maintenance
Changes have been made to the environment where the program is to be used:
Upgrade of hardware
Faster processor
New peripheral devices
New memory chips
Upgrade of Operating System
Cost of this maintenance is usually met by the client

90. Perfective Maintenance
Client requests a change to the original specification usually to enhance the program:
Adding new features
Changing screen layout
Cost of this maintenance is met by the client

91. Glossary Definitions
Write a glossary definition for each of the following at the back of your jotter
Corrective maintenance
Perfective maintenance
Adaptive maintenance

92. Past Paper questions on maintenance
Q. After a computer game is finished and put on sale it still requires maintenance. Describe two kinds of maintenance activity that may be performed.
A. Corrective – previously undetected errors are removed
Adaptive – the environment of the software has changed so changes are made to allow it to run correctly in the new environment
Perfective – changes made to improve the program at the request of the client

93. Q. It is important that a program is readable
Q. It is important that a program is readable. Explain why this is important.
A. Software products always require some form of maintenance. If the program is not readable then programmers will find it very difficult to maintain.
Q. List two techniques used to ensure that a program is readable.
A. Use of meaningful variable names, Internal commentary, Modular programming (sub-routines)

94. Maintenance Costs
Maintenance is expensive to the developer and the client in terms of time and effort.
All the more reason for getting it right in the first place!!
Corrective (17%)
Adaptive (18%)
Perfective (65%)

95. End of Unit Homework
Complete all questions on page 49 as a homework exercise - ensure answers are given at an appropriate level for higher

96. This is what you should have learned
Explanation of the iterative nature of the software development process
Description of the purposes of the software specification, and its status as a legal contract
Explanation of the importance of each stage (analysis, design, implementation, testing, documentation, evaluation, maintenance) of the SDP

97. Identification of the personnel at each stage (client, systems analyst, project manager, programmer, independent test group) and brief description of their roles
Description and exemplification of pseudocode and one graphical design notation (structure diagram or other suitable) including data flow
Description and exemplification of top-down design and stepwise refinement

98. Explanation of the need for systematic and comprehensive testing
Explanation of the need for documentation at each stage
Evaluation of software in terms of robustness, reliability, portability, efficiency and maintainability
Description and exemplification of corrective, adaptive and perfective maintenance

99. End of Topic Activities
Complete the end of unit evaluation sheet
Make sure you have a glossary definition for all the key words on page 43
Complete ActiVote Assessment