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In software engineering, coupling is the degree of interdependence between software modules, a measure of how closely connected two routines or modules are, [1] and the strength of the relationships between modules. [2] Coupling is not binary but multi-dimensional. [3] Coupling and cohesion. Coupling is usually contrasted with cohesion.
Cohesion is often contrasted with coupling. High cohesion often correlates with loose coupling, and vice versa. [2] The software metrics of coupling and cohesion were invented by Larry Constantine in the late 1960s as part of Structured Design, based on characteristics of “good” programming practices that reduced maintenance and ...
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.
Four types of autonomy, which promote loose coupling, are: reference autonomy, time autonomy, format autonomy, and platform autonomy. [3] Loose coupling is an architectural principle and design goal in service-oriented architectures. Eleven forms of loose coupling and their tight coupling counterparts are listed in: [4]
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.
The database schema is the structure of a database described in a formal language supported typically by a relational database management system (RDBMS). The term " schema " refers to the organization of data as a blueprint of how the database is constructed (divided into database tables in the case of relational databases ).
Fifth normal form (5NF), also known as projection–join normal form (PJ/NF), is a level of database normalization designed to remove redundancy in relational databases recording multi-valued facts by isolating semantically related multiple relationships.
Codd's twelve rules [1] are a set of thirteen rules (numbered zero to twelve) proposed by Edgar F. Codd, a pioneer of the relational model for databases, designed to define what is required from a database management system in order for it to be considered relational, i.e., a relational database management system (RDBMS).