1. Building Systems & Applications Software Development, Programming, & Languages10
Chapter

2. Chapter Topics
Systems Development & the Life Cycle of a Software Project
Programming: Traditionally a Five-Step
Procedure
Five Generations of Programming Languages
Programming Languages Used Today
Object-Oriented & Visual
Programming
Markup & Scripting
Languages

3. 10.1 Systems Development & the Life Cycle of a Software Project

4. Purpose of a System
A system is a collection of related components that interact to perform a task in order to accomplish a goal
A computer-based system consists of hardware, software, people, procedures, and data, as well as communications setups

5. How It Starts, Who’s Involved
Users: The new system must ALWAYS be developed in consultation with the people who will be using the completed system
Management: Managers within an organization should be consulted about the system, because they control the budget and resources
Technical staff: The Information Systems or IT staff must be involved, because they will have to execute the project or work with the people who do
Systems Analyst: Information specialist who performs systems analysis, design, and implementation

6. Six Phases of Systems Analysis and Design
Systems analysis and design is a six-phase problem-solving procedure for examining an information systems and improving it
The systems development life cycle (SDLC) is the particular step-by-step process followed during systems analysis and design

7. Systems Development Life Cycle (Six Phases):
Preliminary investigation
Systems analysis
Systems design
Systems development
Systems implementation
Systems maintenance
Information systems are frequently revised and upgraded
Steps in the cycle often overlap

8. SDLC

9. SDLC Phase 1: Conduct a Preliminary Investigation
Conduct a preliminary analysis
Propose alternative solutions
Interview people within the organization
Study what competitors are doing
Decide to leave the system as is, improve it, or develop a new system
Describe costs and benefits
Submit a preliminary plan with recommendations
This should be a written report
Get management approvals for next phase

10. SDLC Phase 1

11. SDLC Phase 2: Analyze the System
Gather data
Interview employees and managers
Develop, distribute, analyze questionnaires
Review current written documents
Observe people and processes at work
Analyze the data
Use modeling tools, such as CASE tools
Create a data flow diagram to show how data flows through the system

12. Phase 2: Analyze the System (continued)
Write a report
Document how the current system works
Document problems with the current system
Describe the requirements for the new system
Recommend what to do next
Get management approval to proceed

13. SDLC Phase 2

14. Data Flow Diagram

15. SDLC Phase 3: Design the System
Do a preliminary design
Often involves prototyping and continued use of CASE tools
Do a detail design, showing:
Output requirements
Input requirements
Storage requirements
Processing requirements
System controls
Backup
Write a report and get approval for next phase

16. SDLC Phase 3

17. SDLC Phase 4: Develop the System
Develop or acquire the software
Make-or-buy decision
If creating own system, programming (coding must be done)
Acquire or upgrade the hardware
Test the system
Unit testing: performance of system’s individual parts tested
System testing: parts are linked and tested to see if they work together properly; real data may be used

18. SDLC Phase 4

19. Phase 5: Implement the System
Choose a strategy to convert to the new system
Direct implementation: quit the old and start using the new
Parallel implementation: use both the old and the new side by side, until the new system has been proved reliable
Phased implementation: phase in parts of new in gradually as parts of old are phased out
Pilot implementation: have the new system tried out by a few users
Train the users

20. SDLC Phase 5

21. SDLC Phase 6: Maintain & Update the System
Perform system audits and periodic evaluations
Make changes to the system based on new conditions
Finalize documentation
Note that documentation should have been continuously maintained during the entire SDLC

22. SDLC Phase 6

23. 10.2 Programming
Traditionally a Five-Step Procedure

24. Programming is done during phase 4 of the SDLC The five steps:
A program is a list of instructions that the computer must follow to process data into information
Programming is done during phase 4 of the SDLC
The five steps:
Clarify/define the problem
Design the program
Code the program
Test the program
Document and maintain the program

25. Programming Step 1: Clarify the Programming Needs
Clarify objectives & users
Clarify desired outputs
Clarify desired inputs
Clarify the desired processing
Double-check the feasibility of implementing the program
Document the analysis

26. Programming Step 1

27. Programming Step 2: Design the Program
Create an algorithm, or set of clear steps, to solve the problem
Use structured programming approach
Determine program logic using top-down approach and modules, using a hierarchy chart (graphic form) and pseudocode (narrative form)

28. Programming Step 2

29. Algorithms The taxi algorithm: Go to the taxi stand. Get in a taxi.
Give the driver my address.
The call-me algorithm:
When your plane arrives, call my cellphone.
Meet me outside baggage claim.
The rent-a-car algorithm:
Take the shuttle to the rental car place.
Rent a car.
Follow the directions to get to my house.
The bus algorithm:
Outside baggage claim, catch bus number 70.
Transfer to bus 14 on Main Street.
Get off on Elm street.
Walk two blocks north to my house.

30. Hierarchy Chart

31. Pseudocode

32. Step 2: Design the Program (continued)
Structured programming
Use control structures:
Sequence: one statement follows another in logical order
Selection: IF-THEN-ELSE
Iteration (loop): DO UNTIL / DO WHILE

33. Program Flowchart & Symbols

34. Three Control Structures

35. Programming Step 3: Code the Program
Translate the logic requirement from flowcharts and pseudocode into a programming language
Select a programming language (set of rules that tells the computer what operations to do)
Each programming language has a syntax, or set of grammatical rules to follow to write valid expressions
Syntax rules must be followed or there will be syntax errors
Computers don’t understand what you want, only what you type in

36. Programming Step 3

37. Programming Step 4: Test the Program
Desk checking is reading through, or checking, the program for syntax errors and logic errors
Debugging is the process of detecting, locating, and removing all syntax errors and logic errors in a computer program
Beta testing is the process of testing the program using real data
One phase of testing uses correct data
Once the program works, the next phase of testing uses invalid data and untrained users to root out hidden errors

38. Programming Step 5: Document and Maintain the Program
Documentation is written descriptions of what a program is and how to fix it; should be done through all 5 steps
User documentation – for the people who will use the program (e.g., user manual – hardcopy or CD, and online)
Operator documentation – for the computer operators, so they know what to do if the program or hardware malfunctions
Programmer documentation – for the next programmer who must modify and maintain what has been written
Maintain the program – keep everything in working condition

39. Programming Step 5

40. Summary of Programming Steps

41. 10.3 Five Generations of Programming Languages

42. First Generation: Machine Language
The basic language of the computer – all 0s and 1s
Each CPU model has its own machine language, thus machine language is machine dependent
Not convenient for people to read and use
Evolution of languages started in 1945

43. Second Generation: Assembly Language
Low-level mnemonic version of machine language; uses abbreviations and simple words
Faster to program in than machine language
Is also machine dependent
Assembler program needed to translate assembly language into machine language

44. Machine Language
Assembly Language

45. Third Generation: High-level Languages (Procedural Languages)
These languages resemble human language (e.g., English) and are portable (not machine dependent)
Examples are FORTRAN, COBOL, BASIC, Pascal, C
The programmer writes the source code, then uses a translator program to interpret or compile the code into machine language (object code)
Interpreter translates and executes immediately
Compiler translates and saves the code as an entire unit to be executed later

46. Compiler

47. Fourth Generation: Very-High-Level or Problem-Oriented Languages
Easier to program in than third-generation languages
Three types:
Report generators (RPGIII)
Query languages (SQL)
Application generators (NOMAD, FOCUS)—used to create parts for other programs

48. Fifth Generation: Natural Languages
Used mainly for artificial intelligence (AI) and neural networks
Use regular human languages

49. Reviews of Language Generations

50. 10.4 Programming Languages Used Today

51. FORTRAN COBOL The language of mathematics
The first high-level language written
A machine-independent procedural language
COBOL
The most-frequently used language for business legacy applications on large computers

52. BASIC
Designed to be an easy language to use and learn programming with
Usually run from an interpreter, but can be compiled
Procedural language
Supplanted by Microsoft’s Visual Basic for commercial/business use
Pascal
Designed to be a language to teach programming
Structured, compiled language
Not used in business or commercial companies

53. C
General-purpose machine-independent compiled language developed for mid-range computers
Used for portability, operating systems. And scientific use
Used to write the Unix operating system
Widely used for writing common software applications and is necessary for programmers to know
C++
Enhanced object-oriented version of C; used for Microsoft system software and many web applications

54. LISP: For Artificial Intelligence Programs
Third-generation language
Used to control AI programs
Used to write expert systems and natural language programs

55. 10.5 Object-Oriented & Visual Programming

56. In object-oriented programming (OOP), data and processing instructions are combined into a self-sufficient object that can be reused
Object
Self-contained module consisting of reusable code
Message
The instruction received by the object indicating it is time to perform an action
Method
The processing instructions within the object to perform the specified action

57. Three basic concepts of OOP
Encapsulation
One object contains (encapsulates) both data and relevant processing instructions
Inheritance
One object can be used as the foundation for other objects
Objects can be arranged in hierarchies – classes and subclasses
Objects can inherit actions and attributes from one another
Polymorphism
Allows a single definition to be used with different data types and different functions
Means a message produces different results depending on the object it is sent to

58. Examples of OOP languages
C++
Object-oriented language that was developed after C
Often used to write computer games and CPU- and graphics-intensive applications
Java
Developed at Sun Microsystems in early 1990s
Derivative of C++ with simpler memory management and syntax
Used to develop Java applets to be downloaded into web browsers to make websites interactive and more attractive (e.g., with animations)

59. Visual programming is a method of creating programs in which the programmer makes connections by clicking on objects, diagrams, and icons and by interacting with flowcharts
Using a mouse, the programmer drags and drops objects on screen
This makes it fast and easy to build prototype user interfaces and get end-user approval before doing a lot of programming
Visual BASIC is an example of visual programming

60. 10.6 Markup & Scripting Languages

61. A markup language is a kind of coding (“tags”) inserted into text that embeds details about the structure and appearance of the text
HTML is a markup language (Internet use)
Has codes for indicating layout and styling (such as boldface, italics, paragraphs, insertion of graphics, etc.)
SGML: improved markup language
Specifies a syntax for including the markup in documents
Allows users to create and use any markup they wish
Script: short list of self-executing commands embedded in a web page that perform a specified function or routine

62. HTML VRML Hypertext markup language Used to create 2-D web pages
Also lets you insert hypertext links in web pages
VRML
Virtual Reality Modeling (Markup) Language is used to create 3-D web pages, including interactive animation
Requires special VRML browser to view VRML pages
Used by web designers, along with HTML

63. XML
eXtensible Markup Language is a metalanguage written in SGML that allows one to facilitate easy document interchange on the Internet
XML lets you create your own tags (“extensible”)
XML statements define data content
JavaScript
Not the same language as Java
An object-oriented scripting language that adds interactive functions to HTML web pages

64. Flash
Browser add-on that uses Adobe Flash to support animation, streaming audio and video, and games on the Internet
ActiveX
Developed by Microsoft as an alternative to Java for creating interactive web pages
Set of controls or components that enable programs or content of almost any type to be embedded in a web page; comprises reusable components that can be plugged into other applications
ActiveX controls are written in C, C++, Visual BASIC, and Java
Often used by crackers to propagate viruses and/or Trojans; before you allow an ActiveX component to download from your browser to your computer, make sure you trust that website

65. CGI (Common Gateway Interface)
Standard protocol for interfacing external application software with a web server
Manages the exchange of information and makes web pages more interactive
Perl
A general-purpose programming language developed for text manipulation.
Used for web development, network programming, system administration, GUI development, other tasks
Widely used for web server programs to perform automatic tasks such as updating user accounts and newsgroup postings

66. PHP (Personal Home Page, or PHP Hypertext Preprocessor)
Allows creation of dynamic content that interacts with databases
Normally found on Linux servers with MySQL databases
General-purpose scripting language