A set of constrained logical constructs that emphasize on maintenance of functional domain are used for designing conventional components. These logical constructs are sequence, condition, and repetition. Structured programming is a design technique that constrains logic flow to three constructs: sequence, condition, and repetition. These structured constructs help in reducing the complexity of the program and enhances readability, test ability and maintainability.
GRAPHICAL DESIGN NOTATION
- Activity diagram is a descendant of flowchart in which all elements of structured programming are represented.
- In a flowchart, each step in the process is represented by a different symbol and contains a short description of the process step.
- Structured programming constructs should make it easier to understand the design. If unnecessary complexity is introduced by using them without violation, it is better ti violate them.
- Dogmatic use of structured constructs introduces inefficiency.
TABULAR DESIGN NOTATION
- Decision tables translates actions and conditions into a tabular form.
- A decision table is used when a complex set of conditions and actions are encountered within a component.
- Decision table is divided into four quadrants. Upper left quadrant lists all conditions. Lower left quadrant lists all actions. Right hand quadrants form a matrix indicating condition combinations and corresponding actions
Monday, July 25, 2011
Designing Conventional Components- Graphical Design Notation and Tabular Design Notation
Friday, February 25, 2011
How to design conventional components - Graphical Design Notation and Tabular Design Notation
There were some logical constructs developed from which any program could be formed. Each construct has a logical structure. The constructs are sequence, condition, and repetition.
- Sequence implements processing the steps that are essential in the specification of any algorithm.
- Condition provides the facility for selected processing based on some logical occurrence.
- Repetition allows for looping.
Structured programming is a design technique that constrains logic flow to three constructs: sequence, condition and repetition. The structured constructs were supposed to limit the procedural design of software to a small number of predictable operations.
GRAPHICAL DESIGN NOTATION
Activity diagram allows a designer to represent sequence,condition and repetition. Flowchart, like an activity diagram, is quite simple pictorially.
The dogmatic use of only structured constructs can introduce inefficiency when an escape from a set of nested loops or nested conditions is required. Additional complication of all logical tests along the path of escape can hinder the control flow, increase the possibility of error and have a negative impact.
There are two options:
- procedural representation is redesigned so that escape branch is not required at a nested location.
- structured constructs are violated in a controlled manner; that is , a constrained branch out of the nested flow is redesigned.
TABULAR DESIGN NOTATION
Decision tables translates actions and conditions in a tabular form. It is difficult to misinterpret. A decision table is divided into quadrants:
- Upper left quadrant: contains a list of all conditions.
- Lower left quadrant: contains a list of all actions that are possible based on combinations of conditions.
- Right hand quadrant: a matrix that indicates condition combinations and corresponding actions. Each column of matrix may be interpreted as a processing rule.
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