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Loose coupling describes a resilient relationship between two or more systems or organizations with some kind of exchange relationship. Each end of the transaction makes its requirements explicit and makes few assumptions about the other end. The notion of loose coupling is found in computer systems, and was introduced into organizational studies by Karl Weick. Karl E Weick (born October 31, 1936 in Warsaw Indiana) is an American organizational theorist who is noted for introducing the notions of " Loose

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Loose coupling in computing

In computer science, coupling or dependency is the degree to which each program module relies on each one of the other modules

Loosely coupled systems are considered useful when either the source or the destination computer systems are subject to frequent changes.

Definition

Loose coupling describes an approach where integration interfaces are developed with minimal assumptions between the sending/receiving parties, thus reducing the risk that a change in one application/module will force a change in another application/module.

Loose coupling has multiple dimensions. Integration between two applications may be loosely coupled in time using Message-oriented middleware, meaning the availability of one system does not affect the other. Message-oriented middleware (MOM is a client/server infrastructure that increases the interoperability portability and flexibility of an application by allowing the application Alternatively, integration may be loosely coupled in format using middleware to perform Data transformation, meaning differences in data models do not prevent integration. This article is about data transformation in computer science (metadata In Web Services or Service Oriented Architecture, loose coupling may mean simply that the implementation is hidden from the caller. A Web service (also Web Service) is defined by the W3C as "a software system designed to support interoperable machine-to-machine interaction Service-oriented architecture ( SOA) is a method for Systems development and integration where functionality is grouped around Business processes

Loosely coupled services, even if they use incompatible system technologies, may be joined to create composite services, or disassembled just as easily into their functional components. Participants can establish (normatively or inceptively) a shared semantic framework to ensure messages retain a consistent meaning across participating services.

Alternate definition

Loose coupling also describes a computer system where two or more physical processors are sharing storage disks with each other in a real time environment. The system must be designed such that the code to be shared is reentrant and that the records to be shared are protected by record locking. Record locking is the technique of preventing simultaneous access to data in a Database, to prevent inconsistent results

Measuring coupling

The degree of loose coupling can be measured by noting the number of changes in data elements that could occur in the sending or receiving systems and determining if the computers would still continue communicating correctly. In Metadata, the term data element is an atomic unit of data that has An identification such as a Data element name A clear Data element definition These changes include items such as:

  1. new data elements being added to messages
  2. data element order being changed
  3. names or structures of data elements being changed
  4. data elements being omitted

Methods for decreasing coupling

Loose coupling of interfaces can be dramatically enhanced when publishers of data transmit messages using a flexible file format such as XML to enable subscribers to publish clear definitions of how they subsequently use this data. Don't change "Extensible" For example, a subscriber could publish the collection of statements used to extract information from a publisher's messages by sharing the relevant XPath expressions used for data transformation. XPath (XML Path Language is a language for selecting nodes from an XML document This would allow a responsible data publisher to test whether their subscriber's extraction methods would fail when a published format changes.

Loose coupling of services can be enhanced by reducing the information passed into a service to the key data. For example, a service that sends a letter is most reusable when just the customer identifier is passed and the customer address is obtained within the service. This decouples services because services do not need to be called in a specific order (e. g. GetCustomerAddress, SendLetter)

Note that loose coupling is not universally positive. If systems are de-coupled in time using Message-oriented middleware, it is difficult to also provide transactional integrity. Message-oriented middleware (MOM is a client/server infrastructure that increases the interoperability portability and flexibility of an application by allowing the application Data replication across different systems provides loose coupling (in availability), but created issues in maintaining synchronisation.

Loose coupling in organizations

The notion of loose coupling was introduced into organizational studies by Karl Weick. In computer science, coupling or dependency is the degree to which each program module relies on each one of the other modules

See also

References

External links

John Seely Brown (also known as JSB is a researcher who specializes in organizational studies with a particular bent towards the organizational implications of computer-supported activities

Dictionary

loose coupling

-noun

  1. (computer science) A lowly interdependent coupling between program modules.
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