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The Re-engineering and Reuse of Software

The Re-engineering and Reuse of Software. Patrick A.V. Hall and Lingzi Jin Vol 1, p.335-351 Presented by: Andrew Wheeler. Overview. Definitions Introduction Historical Background Implementations Challenges Conclusions. Definitions. Re-engineering

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The Re-engineering and Reuse of Software

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  1. The Re-engineering and Reuse of Software Patrick A.V. Hall and Lingzi Jin Vol 1, p.335-351 Presented by: Andrew Wheeler

  2. Overview • Definitions • Introduction • Historical Background • Implementations • Challenges • Conclusions

  3. Definitions • Re-engineering • The combination of reverse engineering and forward engineering • The concept of “redoing” a software system • Reuse • Using a given piece of software to solve more than one problem • Reverse engineering • The tools and methods used to understand software • Figuring out a software system for potential redeployment

  4. Introduction • Software re-engineering and reuse are concerned with maximizing software usage for any given development effort • Both are used to maximize profit and minimize turnaround time • Software re-engineering and reuse also help minimize staff • The more code you can reuse the less code you have to write and rewrite

  5. Introduction (cont) • Reuse not only applies to using a piece of software: • Reuse designs and ideas thrown out during design phase • May have use in other applications • Reverse engineering and reuse can help recover lost investment • Time has already been placed into designing it the first time around.

  6. Historical Background - Reuse • Reuse dates back to sharing of algorithms through publications • Reuse of high level language and packages • Textbook publications • Use of macros and similar assembly instructions • Subroutine entry and exit • For loops, if blocks, arithmetic

  7. Historical Background – Reuse (cont) • Reuse associated with flexibility • Parameterization • Build scripts

  8. Historical Background - Re-engineering • Flow-charting tools have been around for awhile • Now evolved into UML and sequence diagrams • Cross reference listings of variables • Helps understand large pieces of software • Originally designed to help maintain COBOL legacy systems around 1980s

  9. Implementations – Reuse • Integration into lifecycle • Building phase to construct the reusable components into a library • Incorporating those reusable components into the building of a software system • Time required to account for integration issues

  10. Implementations – ReuseComponent based • Central to reuse • Design for “plug and play” • Which components comes from domain analysis • File Input/Output component not needed for a system that won’t write to disk

  11. Implementations – ReuseComponent based • Give clear descriptions and classifications • Avoid over generalization • Map instead of tree • Object oriented programming lends itself to reuse • Objects are often in reusable component form • Inheritance provides contexts for reuse • Sorted Map inherits from Map • Size or granularity

  12. Implementations – Reuse • Reuse in design • Component or components could fulfill a requirement based on specifications • If multiple components are used then requirements must be broken down further • Logging utility = Time utility + Format utility + File utility + Process input utility • Identification, evaluation, modification, and integration • White-box reuse • Reuse with simple modifications of code • Frameworks

  13. Implementations – Reuse • MIL – Module Interconnection Languages – Prieto-Diaz, et. al (1986) • Going beyond procedure calls in code • Helps in system building another higher language • Design with reuse involves transforming the outputs of one components to the inputs of another

  14. Implementations – Re-engineering • Reverse engineering involves abstracting the current system and revealing the nature of the system • Describe the system to a non technical person • Documentation of class methods and members could be used during the process • Outlining tools and sequence diagrams have been in use for many decades

  15. Implementations – Re-engineering • Use of formal transformations • Gather details about an efficient algorithm that may be difficult to understand • Use of wide spectrum language - Ward • An interactive system to abstract details of implementation into Z language and implement Z language in code language of choice

  16. Implementations – Re-engineering • Use of reverse engineering back to specifications – Lano, et. al • Used to reverse engineer COBOL applications • Using good coding practices helps the re-engineering process • Self documenting code • Knowledge of higher level domain concepts helps re-engineering • Knowing for what purpose the software system was used

  17. Implementations – Re-engineering • Using design patterns in code • Helps to know the purpose for a software system and helps the forward process by knowing how to build the system • Object-oriented programming facilitates the reverse-engineering process • Components of the high level systems share the names of the objects

  18. Implementations – Domain Analysis • Identify the major concepts and the relationships between the concepts • Usage of components is determined by the domain in which they will be used • Determine if components needed have already been built • Helps guide the production of components for better reuse • Adequate domain models help scope the components and their usage

  19. Challenges of Re-engineering and Reuse • Personnel issues • “Why buy when you can build?” • Reuse doesn’t always mean buying • Contrast to electronic engineering • Build your own microprocessor? • Payoff issues • Rewarding someone for building a reusable component by royalties?

  20. Challenges of Re-engineering and Reuse • Economical issues • Payoff occurs after component production • Most companies are geared towards producing a system • Gain another contract and reduce turnaround time from reuse • Accounting treats software as consumable and not capital • Concept of making software reusable capital like a desk

  21. Challenges of Re-engineering and Reuse • Legal issues • Protection against physical piracy and intellectual piracy • Use of proprietary software remedies certain issues

  22. Conclusions • Software reuse, re-engineering, and reverse engineering are cutting-edge methodologies • Product Line and Battle Command Product Line • Technology has caught up to these practices • UML • There is a future in adding reuse to the software lifecycle • Economic gains must be established

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