Application Development

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Application Development

• Chapter 10

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Objectives

• Describe the application development process and
  the role of methodologies, models, and tools
• Compare and contrast programming language
  generations
• Explain the function and operation of program
  translation software, including assemblers,
  compilers, and interpreters
• Describe link editing, and contrast static and
  dynamic linking
• Describe integrated application development
  software, including programmers workbenches and
  CASE tools

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Chapter Topics
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The Application Development Process

• The process of designing and constructing
  software translates users information processing
  needs into CPU instructions that, when executed,
  addresses those needs.
• Software development is a complex process that
  requires significant effort and resources.

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The Application Development Process
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The Application Development Process

• Software Development Life Cycle
• The SDLC breaks the complex process of software
  development into smaller and more management
  pieces.
• The output of each phase of the SDLC produces
  input to the next phase.

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The Application Development Process
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The Application Development Process

• Methodologies and Models
• Developers attempt to minimize errors during the
  SDLC by using proven development methodologies.
• Structured methods document requirements by
  modeling the flow of data or the relationship of
  various parts of the process.

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The Application Development Process
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Programming Languages

• Programming languages are used to instruct a
  computer to perform a task.
• Programming languages have evolved from the
  first-generation machine language to scripting
  languages.

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Programming Languages
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Programming Languages
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Programming Languages

• Programming Language Standards Define
• Language syntax and grammar.
• Machine behavior for each instruction or
  statement.
• Test programs with expected warnings, errors and
  execution behavior.

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Programming Languages
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Compilation
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Compilation

• Source Code vs. Object Code
• Program Editor used to input the program into
  the computer system. (Source code)
• Compiler translates some source code
  instructions directly into executable code and
  other source code instructions into library
  calls, which are further processed by the Link
  Editor. (Object Code)

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Compilation
Data Declarations defines the name and data
type of one or more program variables.
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Compilation
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Compilation

• Data Operations
• Any instruction that updates or computes a data
  value.
• For Example f_temperature 212
• The compiler translates a data operation
  instructions into an equivalent sequence of data
  movement and data transformation instructions for
  the target CPU.

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Compilation

• Control structures include
• Unconditional branches (Goto statements)
• Conditional branches (If statements)
• Loops

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Compilation

• Unconditional Branch Example
• F_temperature 0
• Loop F_temperature F_temperature 1
• Goto Loop

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Compilation

• Conditional Branch Example
• If (c_temperature gt -273.16)
• f_temperature (c_temperature 1.8) 32
• Else
• f_temperature -999

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Compilation

• Loop Example
• F_temperature 0
• While (F_temperature lt 10)
• F_temperature F_temperature 1

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Compilation

• Function Calls a call instruction transfers
  control to the first instruction in the function
  and the function transfers control to the
  instruction following the call by executing a
  return instruction.

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Compilation

• Function Example
• float Fahrenheit_to_Celsius(float F)
• float Cel
• Cel (F 32) / 1.8
• return (Cel)

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Link Editing

• A link editor searches an object code for
  external function calls.
• When an external function call is found, the link
  editor searches other object code files or
  compiler libraries to find executable code that
  implements the function.

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Link Editing

• Benefits of a link editor
• A single executable program can be constructed
  from multiple object code files compiled at
  different times.
• A single compiler can generate executable
  programs that run under multiple operating
  systems.

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Link Editing
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Link Editing

• Static and Dynamic Linking
• Dynamic Linking linking is performed during
  program loading or execution.
• Static Linking library and other subroutines
  cannot be changed once they are inserted into the
  executable code.

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Link Editing

• Dynamic Linking Advantages
• Smaller application program files
• Flexibility
• Static Linking Advantages
• Execution speed
• Improved reliability and predictability of
  executable programs

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Interpreters

• Interpreter - reads a single source code
  instruction, translates it into CPU instructions
  or a DLL call.
• Advantage flexibility to incorporate new or
  updated code into an application program.
• Disadvantage increased memory and CPU
  requirements during program execution.

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Interpreters
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Technology Focus
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Symbolic Debugging

• Symbolic debugger features
• Trace calls to specific source code statements or
  subroutines
• Trace changes to variable contents
• Execute source code instructions one at a time
• Detect run-time errors and report them to the
  programmer in terms of specific source code
  instructions and variables

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Symbolic Debugging
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Symbolic Debugging
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Integrated Application Development Tools
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Integrated Application Development Tools

• Programmers Workbenches an integrated set of
  automated support tools to speed development and
  testing.
• Smart program editor
• Compiler and/or interpreter
• Link editor and a large library of classes or
  subroutines

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Integrated Application Development Tools

• Programmers Workbenches cont.
• Interactive facility for prototyping and
  designing user interfaces
• Symbolic debugger
• Integrated window-oriented graphical user
  interface

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Technology Focus
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Integrated Application Development Tools

• CASE Tools refers to a tool that supports the
  SDLC analysis and design phases.
• Front-end CASE tool supports model development.
• Back-end CASE tool supports program development
  based on specific analysis and design models.

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Summary

• Application systems are developed by following
  the steps of the systems development life cycle.
  (SDLC)
• Executable software consists entirely of CPU
  instructions.
• All programming language generations other than
  the first must be translated into CPU
  instructions prior to execution.

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Summary

• Compiled and interpreted programs must be linked
  to libraries of executable functions or methods.
• Application development is more efficiently
  supposed by integrated suites of automated tools.