Systems Analysis & Programming

10 Chapter Systems Analysis & Programming 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

Systems Development • Organizations can make mistakes, and big organizations can make really big mistakes • Murphy’s 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!

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

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

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

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

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

Systems Development • Phase 3: Design the system • Notice that you don’t 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

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 don’t know the software and will show the developers where they forgot something

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

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

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

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

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 differentassembler

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

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

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

Programming Languages Used Today

Object-OrientedWhat 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.

Object-OrientedWhat 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.

Object-OrientedWhat 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).

Object-OrientedWhat 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.

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

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

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

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

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

Systems Analysis & Programming