Systems Architecture, Fifth Edition

1
(No Transcript)
2
Chapter Goals

• 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

3
Chapter Goals (continued)

• Describe link editing, and contrast static and
  dynamic linking
• Describe integrated application development
  software, including programmers workbenches and
  CASE tools

4
(No Transcript)
5
The Application Development Process

• Follows a development methodology
• Develops a set of models
• Uses automated tools

6
(No Transcript)
7
Systems Development Life Cycle (SDLC)

• Follow disciplines and iterations of the Unified
  Process (UP)
• Usually includes two sets of models
• System requirements model
• Design model

8
(No Transcript)
9
Methodologies and Models

• Methodology
• Integrated collection of models, tools, and
  techniques
• UP employs object-oriented analysis, design, and
  deployment models
• Class diagrams document user and system
  requirements

10
Tools

• Wide array to support or completely automate
  software development tasks
• Proper tool selection is a critical and difficult
  undertaking

11
Programming Languages

• Instruct computer to perform a task
• Sometimes called code
• Programmer goals
• Make language easier for people to understand
• Develop languages and development approaches that
  require people to write fewer instructions to
  accomplish a task

12
(No Transcript)
13
Programming Languages

• Summary of capabilities of recent generations
• Instruction explosion
• Database access
• Support for GUIs
• Nonprocedural programming
• All but 1GL must be translated into CPU
  instructions prior to execution (compilers and
  interpreters)

14
(No Transcript)
15
First-Generation Languages

• Required programmers to remember binary codes
  that represented each CPU instruction and to
  specify all operands as binary numbers
• Tedious to program error-prone

16
Second-Generation Languages

• Use mnemonics to represent variables (program
  instruction memory address) and labels (data item
  memory address)
• Easier to manipulate than binary numbers
  assembler translates program into binary CPU
  instructions
• Common in 1950s

17
Third-Generation Languages

• Use mnemonics to represent instructions,
  variables, and labels
• Have degree of instruction explosion greater than
  11
• Translated with compilers, link editors, and
  interpreters
• Machine independent
• Developed before GUIs, database managers, and
  Internet

18
Fourth-Generation Languages

• Majority were proprietary many were optional
  components of database management systems
• Most support mixture of procedural and
  nonprocedural instructions

19
Fifth-Generation Languages

• Nonprocedural language suitable for developing
  software that mimics human intelligence
• Rule processor accepts a starting state as input
  and iteratively applies rules to achieve a
  solution
• First appeared in 1960s not widely used until
  1980s

20
Object-Oriented Programming (OOP) Languages

• View data and programs as two parts of integrated
  whole (object)
• Promote reusability and portability of source
  code
• Uniquely suited to developing real-time programs
• Not clear successors to 5GLs neither
  nonprocedural nor exclusively used for developing
  artificial intelligence

21
OOP languages Objects reside in a specific
location, wait for messages to arrive, and return
a response.
22
Scripting Languages

• Enable programmers to develop applications that
  do most of their work by calling other
  applications and system software
• Enable rapid assembly of application software by
  gluing together capabilities of other programs
• Evolved from 4GLs, though most now incorporate
  OOP concepts

23
Programming Language Standards

• Set by ANSI and ISO
• Include definitions of
• Language syntax and grammar
• Machine behavior for each instruction or
  statement
• Test programs with expected warnings, errors, and
  execution behavior
• Guarantee program portability among operating
  systems and application programs

24
Compilation

• Translates an entire source code file, building a
  symbol table and object code file as output

25
(No Transcript)
26
Compiler

• Checks for syntax and other errors issues
  warning or error messages
• Updates internal tables that store information
  about data items and program components
• Generates CPU instructions or library calls to
  carry out the source code instruction

27
Source Code Instruction Types

• Data declarations
• Data operations
• Control structures
• Function, procedure, or subroutine calls

28
Data Declarations

• Define name and data type of program variables
• Stored in memory allocated by compiler

29
The compiler updates a symbol table to keep track
of data names, types, and assigned memory
addresses.
30
Data Operations

• Instructions that update or compute a data value
• Translated by compiler into equivalent sequence
  of data movement and data transformation
  instructions for target CPU
• Compiler refers to entries in symbol table to
  determine source and destination memory addresses
  for data movement instructions

31
Control Structures

• Source code instructions that control the
  execution of other source code instructions
• Common thread is transfer of control among CPU
  instructions

32
Function Calls

• Named instruction sequences executed by call
  instructions
• Transfer control to the instruction following the
  call by executing a return instruction

33
Implementing Call and Return Instructions

• Compiler generates CPU instructions to
• Pass input parameters to the function
• Transfer control to the function
• Execute CPU instructions within the function
• Pass output parameters back to the calling module
• Transfer control back to the calling module at
  the statement immediately following the function
  call statement

34
(No Transcript)
35
Link Editing

• Statically links external reference calls in
  object code to library functions combines them
  into a single file containing executable code
• Can dynamically link external calls by statically
  linking them to an OS service function that loads
  and executes dynamic-link library (DLL) functions
  at run time
• Always used by interpreters

36
Key Benefits of Link Editors in Program
Translation

• 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

37
(No Transcript)
38
Dynamic and Static Linking

• Static linking
• Library and other subroutines cannot be changed
  once inserted into executable code
• Dynamic linking
• Performed during program loading or execution

39
Advantages of Dynamicand Static Linking

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

40
Interpreters

• Interleave source code translation, link editing,
  and execution, one source code instruction at a
  time
• Advantage (vs. compilation)
• Provide flexibility to incorporate new or updated
  code into an application program (dynamic
  linking)
• Disadvantage (vs. compilation)
• Increase memory and CPU requirements during
  program execution

41
(No Transcript)
42
Java

• Object-oriented programming language and program
  execution environment
• Maximizes reliability of applications and
  reusability of existing code
• Has a standardized target machine language for
  Java interpreters and compilers
• Drawback Reduced execution speed due to use of
  interpreted byte codes and OS translation

43
(No Transcript)
44
Features of Java

• Provision of compilers and virtual machines at
  little or no cost
• Incorporation of JVMs into Web browsers
• Increasing development of application software
  that uses a Web browser as primary I/O device
• Ability of Java programs to execute on any
  combination of computer hardware and OS

45
Symbolic Debugging

• Use of an automated tool for testing executable
  programs able to
• Trace calls to specific source code statements or
  subroutines
• Trace changes to variable contents
• Execute source code instructions one at a time
• Detect and report run-time errors to programmer

46
Symbolic Debugger

• Uses symbol table, memory map, and source code
  files to trace memory addresses to specific
  source code statements and variables
• Inserts debugging checkpoints after each source
  code instruction program execution can be paused
• Debugging vs. production/distribution version
• Incorporated directly in most interpreters

47
(No Transcript)
48
Integrated Application Development Tools
Programmers workbenches CASE tools
Integrated set of automated support tools to speed development and testing Key feature Level of integration among tools Require 2-3 times CPU power, memory, and disk storage of typical workstation Support UP requirements and design disciplines Key feature Support for broad range of system development activities with emphasis on model development
49
Programmers Workbench Components

• Smart program editor
• Compiler and/or interpreter
• Link editor and large library of classes or
  subroutines
• Interactive tool for prototyping and designing
  user interfaces
• Symbolic debugger
• Integrated window-oriented GUI

50
CASE Tools

• Front-end CASE tools
• Support development of requirements and design
  models
• Back-end CASE tools
• Generate program source code from models

51
Summary

• Software development process
• Programming languages
• Compilation and link editing
• Interpretation
• Symbolic debugging
• Application development tools