The Big Picture of Software Development

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The Big Pictureof Software Development

• Glenn Blank
• Professor of Computer Science
• Lehigh University

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National Trends

• The pipeline for women and minorities entering
  computer science (CS) and information technology
  (IT) is shrinking, at a time when the projected
  demand for IT professionals is growing
• Camp, 1997, 1999, Cohoon, 2002
• We must take direct action to attract and retain
  more women to computing at all points in the
  pipeline (i.e., K-12, undergraduate, graduate,
  faculty and industry)
• Camp 1999
• Do you agree? What does this situation mean for
  you?
• Thats why theres Launch-IT!

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Creating Software is like Building a House

• When building a house, the first thing you do is
• Buy some lumber and nails to frame it
• Dig a hole for the foundation
• Get a loan from a bank to pay for it
• None of the above
• First, contractor figures out what the customer
  wants!
• Next, architect designs a blueprint
• Next well, why dont you figure it out?

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How is creating software like building a house?

• Figure out what customer wants Requirements
• Sketch a plan Conceptual design
• Blueprint Architectural design
• Get a loan Cost analysis/risk assessment
• Subcontractors Team with specialists outsource
• Build it Implementation
• Inspect and fix problems Testing
• Maintenance and remodeling Maintenance
• (new releases and versions)

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Multimedia about software engineering
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Objects

• Software objects model real-world objects
• For example, trees, cars, ATMs
• Objects are natural
• We interact with them all the time (vs. lines of
  code or functions)

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Objects and Classes

• Objects are categorized by their type, or class
• An object is an instance of a class
• A software object has a current state and a set
  of possible behaviors
• Attributes describe properties of a class of
  objects
• A car has an make, model, color, etc.
• Methods perform behaviors of a class of objects
• A car can start, accelerate, reverse, park, etc.

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Objects and Classes example

• Object Sue (Class person)
• Attributes height (5), hairColor (blond),
  eyeColor (blue)
• Methods getHeight, getHairColor, getEyeColor,
  setHeight, setHairColor, setEyeColor
• Object Mike (Class person)
• Attributes height (6), hairColor (black),
  eyeColor (hazel)
• Methods getHeight, getHairColor, getEyeColor,
  setHeight, setHairColor, setEyeColor
• What do object instances have in common?
• How are objects instances different?

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Multimedia about Classes and objectsEveryone
gets a CIMEL loginCIMEL means Constructive
Inquiry-Based Multimedia E-Learning
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JVM

• Java programming language compiler (javac)
• A program that translates Java language source
  code into the Java Virtual Machine (JVM) byte
  codes
• JVM Java Virtual Machine
• A program that interprets and executes byte codes
  
• Can interpret and execute Java byte codes on any
  computer platform (PC, Mac, Unix)

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Integrated Development Environment

• IDE
• An environment where programmers develop software
  
• Eclipse is an industrial strength IDE
• DrJava is a novice-oriented IDE

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Object Oriented Software Design

• Design a system as a set of classes
• Expresses as a class diagram
• Unified Modeling Language (UML) is a standard
• OO software encourages software reuse
• For example, reuse input/output, graphics classes
• Java comes with a large library of reusable
  classes
• Why is reuse a good idea?
• Avoid re-inventing the wheelcuts costs
• Lets developers focus on new things
• Reliability reusable software gets tested more