Systems Analysis

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Systems Analysis Programming
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Chapter

• 10.1 Systems Development
• 10.2 Programming A Five-Step Procedure
• 10.3 5 Generations of Programming Languages
• 10.4 Programming Languages Used Today
• 10.5 Object-Oriented Visual Programming
• 10.6 Markup Scripting Languages

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Systems Development

• Organizations can make mistakes, and big
  organizations can make really big mistakes
• Murphys Law Whatever can go wrong, will go
  wrong, and at the worst possible time
• A system
• A collection of related components that interact
  to perform a task in order to accomplish a goal
• Systems Development
• 6-phase process of gathering information about
  system requirements and using that to develop a
  new system that improves productivity

Warning! Road Out!
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Systems Development

• The three kinds of roles (users) of a project
  are
• 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, as they control the
  budget and resources
• Technical staff
• The Information Systems or IT staff must be
  involved so they can make sure the technology is
  there

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Systems Development

• Systems Analyst
• An information specialist who performs systems
  analysis, design, and implementation
• His or her job is to study the information and
  communications needs of an organization and
  determine what changes are needed to deliver
  better information to the people who need it

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Systems Development

• The 6 phases of systems analysis design are

• Information systems are frequently revised and
  upgraded
• Steps in the cycle often overlap

System Develovement Life Cycle
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Systems Development

• 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

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Systems Development

• 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 system modeling tools
• Create a data flow diagram to show how data flows
  through the system
• Write a report and get approvals for next phase
• Document how the current system works
• Document problems with the current system
• Describe the requirements for the new system

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Systems Development

• Phase 3 Design the system
• Notice that you dont design the new system until
  you have done phase 2 since that establishes the
  requirements it must meet!
• Do a preliminary design
• Often involves prototyping
• Do a detail design, showing
• Input requirements
• Output requirements
• Storage requirements
• Processing requirements
• System controls
• Backup
• Write a report and get approvals for next phase

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Systems Development

• Phase 4 Develop the system
• Develop or acquire the software
• Acquire and integrate the hardware
• Test the system
• Unit testing
• Systems testing with both analysts and end-users
• End-user testing is critical, as they dont know
  the software and will show the developers where
  they forgot something

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Systems Development

• Phase 5 Implement the system
• Choose a strategy to convert to the new system
• Direct implementation
• Parallel implementation
• Phased implementation
• Pilot implementation
• Train the users
• Document the system
• Give classes or train the trainers

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Systems Development

• Phase 6 Maintain the system
• Perform periodic evaluations
• Make changes to the system based on new
  conditions
• Document those changes

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Programming A Five-Step Procedure

• A program is a list of instructions that the
  computer must follow to process data into
  information
• The five steps are
• Clarify/define the problem
• Design the program
• Code the program
• Test the program
• Document and maintain the program

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5 Generations of Programming Languages

• 1945 1st Generation Machine Language
• The basic language of the computer all zeros
  and ones
• Each CPU architecture had a different machine
  language

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5 Generations of Programming Languages

• 1945 1st Generation Machine Language
• Mid-1950s 2nd Generation Assembly Language
• Mnemonic version of machine language
• Faster to program in than machine language
• Each CPU architecture had a different assembler

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5 Generations of Programming Languages

• 1945 1st Generation Machine Language
• Mid-1950s 2nd Generation Assembly Language
• Mid-1950s to 60s 3rd Generation High-level
  Languages (procedural languages) such as FORTRAN,
  COBOL, BASIC, C
• These languages are portable (the same across all
  CPUs)
• The programmer writes, then interprets or
  compiles the programs
• The compiler or interpreter translates the code
  into the CPU-specific assembler

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5 Generations of Programming Languages

• 1945 1st Generation Machine Language
• Mid-1950s 2nd Generation Assembly Language
• Mid-1950s to 60s 3rd Generation High-level
  Languages (procedural languages) such as FORTRAN,
  COBOL, BASIC, C
• Early 1970s 4th Generation Problem-oriented
  Languages such as SQL, Intellect, NOMAD, FOCUS
• Easier to program in than 3rd generation
  languages
• Three types are
• Report generators
• Query languages
• Application generators

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5 Generations of Programming Languages

• 1945 1st Generation Machine Language
• Mid-1950s 2nd Generation Assembly Language
• Mid-1950s to 60s 3rd Generation High-level
  Languages (procedural languages) such as FORTRAN,
  COBOL, BASIC, C
• Early 1970s 4th Generation Problem-oriented
  Languages such as Intellect, NOMAD, FOCUS
• Early 1980s 5th Generation Natural Languages
• Programming languages that use human language to
  give people a more natural connection with
  computers
• Part of the field of artificial intelligence

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Programming Languages Used Today
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Object-Oriented What Is an Object?

• Objects are key to understanding object-oriented
  technology.
• Look around right now and you'll find many
  examples of real-world objects your dog, your
  desk, your television set, your bicycle.

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Object-Oriented What Is an Object?

• Real-world objects share two characteristics
• They all have state and behavior.
• Dogs have state (name, color, breed, hungry) and
• behavior (barking, fetching, wagging tail).
• Identifying the state and behavior for real-world
  objects is a great way to begin thinking in terms
  of object-oriented programming.

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Object-Oriented What Is an Object?

• Software objects are conceptually similar to
  real-world objects they too consist of state and
  related behavior.
• An object stores its state in properties (fields,
  attributes or variables in some programming
  languages)
• An object exposes its behavior through methods
  (functions in some programming languages).

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Object-Oriented What Is a Method?

• Methods operate on an object's internal state and
  serve as the primary mechanism for
  object-to-object communication.
• Hiding internal state and requiring all
  interaction to be performed through an object's
  methods is known as data encapsulation a
  fundamental principle of object-oriented
  programming.

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Object-Oriented Visual Programming

• In Object oriented Programming (OOP) data and
  processing instructions are combined into an
  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

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Object-Oriented Visual Programming

• Black Box
• Objects are like a black box in that the
• actions and the objects are specified, but
• the methods used are internal to the object
• This means the programmer that uses an object
  does not need to know how the program inside the
  object does what it does
• For example, Microsoft Excel is like an object
• Most of us use Excel without understanding what
  the programmers at Microsoft did to make Excel
  work
• If we had to know that, it would take a lot
  longer to learn how to use Excel!
• Programmers who use objects can write programs a
  lot faster, because objects save so much work

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Object-Oriented Visual Programming

• 3 basic concepts of OOP
• Encapsulation
• One object contains (encapsulates) both
• State Data (properties)
• Relevant processing instructions or behavior
  (methods)
• 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
  each other
• 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

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Object-Oriented Visual Programming
Example of Inheritance Hierarchy with
Specialization
The Door class
Actions performed by a door (behavior)
Subclasses of doors inherit from the door class,
but also have their own unique actions and
attributes
Notice we only list the actions attributes when
they differ from those of class
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Object-Oriented Visual Programming

• Visual Basic is an example of visual programming
• Using a mouse, the programmer drags and drops
  objects on screen
• The objects are arranged to make up the graphical
  user interface for the program being written
• By double-clicking on those objects, the
  programmer can get into a coding window and write
  the programs to control the actions and behaviors
  of those objects
• This makes it fast and easy to build prototype
  user interfaces and get end-user approval before
  doing a lot of programming