What is difference and similar between loosely-coupled system and tightly-coupled system?

Answer 1

The way I understand it is, that tightly coupled architecture does not provide a lot of flexibility for change when compared to loosely coupled architecture.

For eg., if two disparate systems exchange messages, the message format has to be the same if they are tightly coupled. If the source uses java, the receiver should be able to read the message using java. Also, if any change is made is made to the source or the receiver systems, the other end has to be modified appropriately.

But in case of loosely coupled architectures, message formats or operating platforms or revamping the business logic does not impact the other end. If the system is taken down for a revamp, of course the other end will not be able to access the service for a while but other than that, the unchanged end can resume message exchange as it was before the revamp.

Answer 2

Tightly coupled clusters are a group of machines that are largely dependent on each other. They are often used when latency is an important factor in the application. For example, a web cluster is often a tightly coupled cluster as the web servers/application servers require quick and consistent access to a shared storage system (network filesystem or database).

Loosely coupled clusters are a group of machines (or groups of groups) which can operate independent of each other. Communications between nodes (or subclusters) is often done via a queuing system. Tightly coupled clusters are a group of machines that are largely dependent on each other. They are often used when latency is an important factor in the application. For example, a web cluster is often a tightly coupled cluster as the web servers/application servers require quick and consistent access to a shared storage system (network filesystem or database).

Loosely coupled clusters are a group of machines (or groups of groups) which can operate independent of each other. Communications between nodes (or subclusters) is often done via a queuing system.

Answer 3

Tightly coupled system refers to group of classes that are highly dependent on one another. The loosely coupled system can be tested and consumed independently of the other concrete classes.