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Introduction

Explore the advantages of software reuse, including reduced development time, early market access, and the use of standard, well-tested components. Discover the challenges and benefits of reusing knowledge and components, as well as the importance of domain analysis in identifying reusable components. Learn how to overcome basic issues in software reuse, such as component creation, indexing, search, understanding, adaptation, and repository maintenance. Reuse at an organizational level can significantly improve reusability and integration with reuse repositories.

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Introduction

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Presentation Transcript

  1. Introduction • Software is becoming very expensive: • a possible way to reduce cost: • reuse parts from previously made software. • assemble software from off-the-shelf components.

  2. Introduction • Advantages of reuse also include: • reduced number of defects: • standard and well-tested components are reused. • reduced development time: • provide early market access for products.

  3. Software reuse • Software development with reuse: • similar to an electronic engineer building an electronic circuit: • uses standard types of electronic ICs and other components.

  4. What can be reused? • Specification • Design • Code • Test cases • At the most abstract level: • knowledge

  5. Reuse of Knowledge • More difficult compared to day-to-day reuse of knowledge: • developers vary over time and over projects • difficult to remember details of potentially reusable development knowledge.

  6. Why almost no software reuse so far? • Engineers working in industry often have a frustrated feeling: • current system is similar to last few systems they have already built • everything is being built from scratch • current system is behind schedule: • no one has time to figure out what this similarity really means.

  7. Another complaint • In spite of having software components available for reuse: • programmers have preferred to create their own, because: • available components are difficult to understand • difficult to adapt to new application

  8. Basic Issues in Software Reuse • Component creation • Component indexing • Search • Understanding • Adaptation • Repository maintenance

  9. Basic Issues • Component creation: • Identify reusable components • Component indexing: • classification of reusable components • so that they can be easily searched when we look for a component to reuse.

  10. Basic Issues • Search: • search for right components in a database of components • requires a proper method to describe components

  11. Basic Issues • Understanding: • to decide whether we can use some component • we need a precise and sufficiently complete understanding of what the component does.

  12. Basic Issues • Adaptation: • A selected component may not exactly fit the problem at hand • Tinkering with the code is not satisfactory: • in any case justified only if thoroughly understood

  13. Basic Issues • Repository maintenance: • component entering • tracking faulty components • new applications emerge • older applications become obsolete • components might need changes • obsolete components might have to be removed

  14. Domain analysis • Aim: • identify reusable components for a problem domain. • identification of right kind of reusable information is a difficult problem.

  15. Domain analysis • Domain analysis identifies: • objects, operations and relationship among them. • Consider airline reservation: • objects are • seats, flights, airports, crew, meal orders • Operations are • scheduling a flight, reserving a seat, assigning a crew to a flight, etc.

  16. Domain analysis • Analysis of an application domain: • to identify the reusable components • Actual construction of reusable components for a domain • is called domain engineering.

  17. Reuse at organization level • Reusability should be a standard part in: • specification, design, implementation, test, etc. • Ideally there is a steady flow of reusable components: • in practice, things are not so simple.

  18. Reuse at organization level • Extracting reusable knowledge from past projects: • presents difficulties not encountered in working with a current project • typically original developers are no longer available for consultation.

  19. Summary • Basic issues in reuse: • Component creation • Component indexing • Search • Understanding • Adaptation • Repository maintenance

  20. Summary • Creation of highly reusable components is a very difficult problem • a promising approach is domain analysis • Domain analysis: • aims to identify reusable components for a problem domain

  21. Summary • Application generators: • translate specifications into application programs. • facilitate reuse • not very flexible, if new concepts need to be supported.

  22. Summary • Reuse at organization level • assess product’s potential for reuse • refine product for greater reusability • integrate product with reuse repository

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