Software Engineering

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Software Engineering
Dr. Mohamed Fayad, Associate Professor Department
of Computer Science Engineering University of
Nebraska, Lincoln Ferguson Hall, P.O. Box
880115 Lincoln, NE 68588-0115 http//www.cse.unl.e
du/fayad
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Lesson 33 Dealing with Legacy Systems
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Lesson Objectives

• Understand how to reuse non-OO software
• Learn how to encapsulate non-OO code
• Recognize required language features
• Learn how to develop object-oriented
  encapsulations of non-OO code
• Learn how to manage dual documentation

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OO SOFTWARE COMMUNICATES VIA WELL DEFINED
INTERFACES
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NON-OO SOFTWARE MUST BE COMPLETELY ENCAPSULATED
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LANGUAGE INTERFACING RULES

• Language interface must maintain OO structure
• No data coupling
• Well defined interfaces
• Information Hiding
• Object-Oriented language should be main part of
  program
• Helps keep as many OO features as possible
• Maximum benefit of maintainability and
  extensibility

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RULES TO ENCAPSULATE HERITAGE CODE INTO OBJECTS

• Look for clean interfaces
• If necessary, create messages to pass data - no
  data coupling allowed

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MANAGING OO/NON-OO DOCUMENTATION(DOD-STD-2167A
EXAMPLE)
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REUSING NON-OO SOFTWARE SUMMARY

• Non-OO software can be reused within OO systems
• Non-OO software must be completely encapsulated
• OO notation can be developed for encapsulated
  heritage software
• OO documentation can be developed using the
  encapsulation