Data Structure-Oriented Design (Early 70s)

Q: Explain about 'Data Structure-Oriented Design (Early 70s)'

• Soon it was discovered:

-        it is important to pay more attention to the design of data structures of a program

*        than to the design of its control structure.

• Techniques which emphasize designing the data structure:

-        derive program structure from it:

*        are called data structure-oriented design techniques. 

• Example of data structure-oriented design technique:

-        Jackson's Structured Programming(JSP) methodology

*        developed by Michael Jackson in 1970s.

• JSP technique:

-         program code structure should correspond to the data structure.

• In JSP methodology: 

-        a program's data structures are first designed using notations for 

*        sequence, selection, and iteration. 

-        Then data structure design is used :

*        to derive the program structure.

• Several other data structure-oriented Methodologies also exist:

-         e.g., Warnier-Orr Methodology. 

Data Flow-Oriented Design  (Late 70s)

• Data flow-oriented techniques advocate:

-        the data items input to a system must first be identified,

-        processing  required on the data items to produce the required outputs should be determined.

• Data flow technique identifies:

-        different processing stations (functions) in a system 

-        the items (data) that flow between processing stations.

• Data flow technique is a generic technique:

-        can be used to model the working of any system

·        not just software systems.

•  A major advantage of the data flow technique is its simplicity

Data Flow Model of a Car Assembly Unit

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difference betwen control flow oriented and data flow oriented design

Q: State at least two basic differences between control flow-oriented and data flow-oriented design techniques.
Ans.: - Control flow-oriented design deals with carefully designing the program’s control structure. A program's control structure refers to the sequence, in which the program's instructions are executed, i.e. the control flow of the program. But data flow-oriented design technique identifies:
• Different processing stations (functions) in a system
• The data items that flows between processing stations