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Chapter Goals

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.

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Chapter Goals

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  1. 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 Systems Architecture, Fifth Edition

  2. Chapter Goals (continued) • Describe link editing, and contrast static and dynamic linking • Describe integrated application development software, including programmer’s workbenches and CASE tools Systems Architecture, Fifth Edition

  3. Systems Architecture, Fifth Edition

  4. The Application Development Process • Follows a development methodology • Develops a set of models • Uses automated tools Systems Architecture, Fifth Edition

  5. Systems Architecture, Fifth Edition

  6. 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 Systems Architecture, Fifth Edition

  7. Systems Architecture, Fifth Edition

  8. 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 Systems Architecture, Fifth Edition

  9. Tools • Wide array to support or completely automate software development tasks • Proper tool selection is a critical and difficult undertaking Systems Architecture, Fifth Edition

  10. 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 Systems Architecture, Fifth Edition

  11. Systems Architecture, Fifth Edition

  12. 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) Systems Architecture, Fifth Edition

  13. Systems Architecture, Fifth Edition

  14. 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 Systems Architecture, Fifth Edition

  15. 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 Systems Architecture, Fifth Edition

  16. Third-Generation Languages • Use mnemonics to represent instructions, variables, and labels • Have degree of instruction explosion greater than 1:1 • Translated with compilers, link editors, and interpreters • Machine independent • Developed before GUIs, database managers, and Internet Systems Architecture, Fifth Edition

  17. Fourth-Generation Languages • Majority were proprietary; many were optional components of database management systems • Most support mixture of procedural and nonprocedural instructions Systems Architecture, Fifth Edition

  18. 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 Systems Architecture, Fifth Edition

  19. 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 Systems Architecture, Fifth Edition

  20. OOP languages: Objects reside in a specific location, wait for messages to arrive, and return a response. Systems Architecture, Fifth Edition

  21. 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 Systems Architecture, Fifth Edition

  22. 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 Systems Architecture, Fifth Edition

  23. Compilation • Translates an entire source code file, building a symbol table and object code file as output Systems Architecture, Fifth Edition

  24. Systems Architecture, Fifth Edition

  25. 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 Systems Architecture, Fifth Edition

  26. Source Code Instruction Types • Data declarations • Data operations • Control structures • Function, procedure, or subroutine calls Systems Architecture, Fifth Edition

  27. Data Declarations • Define name and data type of program variables • Stored in memory allocated by compiler Systems Architecture, Fifth Edition

  28. The compiler updates a symbol table to keep track of data names, types, and assigned memory addresses. Systems Architecture, Fifth Edition

  29. 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 Systems Architecture, Fifth Edition

  30. Control Structures • Source code instructions that control the execution of other source code instructions • Common thread is transfer of control among CPU instructions Systems Architecture, Fifth Edition

  31. Function Calls • Named instruction sequences executed by call instructions • Transfer control to the instruction following the call by executing a return instruction Systems Architecture, Fifth Edition

  32. 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 Systems Architecture, Fifth Edition

  33. Systems Architecture, Fifth Edition

  34. 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 Systems Architecture, Fifth Edition

  35. 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 Systems Architecture, Fifth Edition

  36. Systems Architecture, Fifth Edition

  37. 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 Systems Architecture, Fifth Edition

  38. Advantages of Dynamicand Static Linking • Dynamic • Smaller application program executable files • Flexibility • Static • Execution speed • Improves reliability and predictability of executable programs Systems Architecture, Fifth Edition

  39. 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 Systems Architecture, Fifth Edition

  40. Systems Architecture, Fifth Edition

  41. 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 Systems Architecture, Fifth Edition

  42. Systems Architecture, Fifth Edition

  43. 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 Systems Architecture, Fifth Edition

  44. 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 Systems Architecture, Fifth Edition

  45. 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 Systems Architecture, Fifth Edition

  46. Systems Architecture, Fifth Edition

  47. Integrated Application Development Tools Systems Architecture, Fifth Edition

  48. Programmer’s 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 Systems Architecture, Fifth Edition

  49. CASE Tools • Front-end CASE tools • Support development of requirements and design models • Back-end CASE tools • Generate program source code from models Systems Architecture, Fifth Edition

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