Coupling and Cohesion, Essay Example

Utilization of Cohesion and Coupling in a Structure Chart

Cohesion and coupling are important parts of evaluating a system design.  The optimal module will have a high degree of cohesion and be minimally, or loosely, coupled.  Cohesion measures a system’s scope and processing tendencies.  For instance, a module that reflects a simple task is highly cohesive, which is a highly desirable outcome.  A complex module showing multiple tasks can be made more cohesive by breaking it into separate units, each with individual functions.

A cohesive model is, ultimately, easier to reuse because it is concentrated upon a single task.  For instance, a module designated “verify social security number” is far more cohesive than one named “determine sales tax and print invoice.”  In the latter case, coupling would be a desirable tool because it measures relationships and the degree to which modules relate to one another.

Cohesion and coupling are highly useful throughout the process by which a structure chart is created.  Developing a structure chart is a four-step process, beginning with a review of DFDs and object models to identify processes.  Then, program modules are identified to determine control-dependence relationships, and symbols are added.  A final review is made to ensure accuracy.

The optimal outcome of this process is to keep functions that change together nearby in the chart, allow for independence between functions that are unrelated and minimize code duplication.  Working toward higher cohesion and loose coupling can produce a structure chart that meets these criteria.   The following is an example of a structure that might utilize coupling, since the process it outlines contains different functions:

Software Engineering: Analysis and Design-CSE3308; Monash University School of Computer Science and Software Engineering. 2004.