Search results
Results From The WOW.Com Content Network
Coupling and cohesion. Coupling is usually contrasted with cohesion. Low coupling often correlates with high cohesion, and vice versa. Low coupling is often thought to be a sign of a well-structured computer system and a good design, and when combined with high cohesion, supports the general goals of high readability and maintainability ...
Cohesion is an ordinal type of measurement and is usually described as “high cohesion” or “low cohesion”. Modules with high cohesion tend to be preferable, because high cohesion is associated with several desirable software traits including robustness, reliability, reusability, and understandability. In contrast, low cohesion is ...
The model is named after database pioneer Charles Bachman, and mostly used in computer software design. In a relational model, a relation is the cohesion of attributes that are fully and not transitive functional dependent [clarify] of every key in that relation. The coupling between the relations is based on accordant attributes.
The indirection pattern supports low coupling and reuses potential between two elements by assigning the responsibility of mediation between them to an intermediate object. An example of this is the introduction of a controller component for mediation between data (model) and its representation (view) in the model-view-controller pattern.
This is a UML diagram illustrating an example of loose coupling between a dependent class and a set of concrete classes, which provide the required behavior: For comparison, this diagram illustrates the alternative design with strong coupling between the dependent class and a provider:
Architectural and structural complexity are an area of research in systems theory to measure the cohesion and coupling and is based on the metrics commonly used in software development projects. Zeigler, Kim, and Praehofer present a theory of modeling and simulation which provides a conceptual framework and an associated computational approach ...
The internal structure of the database should be unaffected by changes to the physical aspects of the storage: For example, a changeover to a new disk. The three levels are: External Level (User Views): A user's view of the database describes a part of the database that is relevant to a particular user. It excludes irrelevant data as well as ...
Example of a system context diagram. [14] Context diagrams are diagrams that represent the actors outside a system that could interact with that system. [15] This diagram is the highest level view of a system, similar to block diagram, showing a, possibly software-based, system as a whole and its inputs and outputs from/to external factors.