A message queue is a software component that enables asynchronous communication between different processes. The basic idea is that a process can put messages into a queue, and a different process can get messages from the queue. This allows for a loose coupling between the components involved in the communication, as each component can operate at its own pace and without direct knowledge of the state or operation of the other components.
There are different types of message queues…
In-memory message queues: These reside entirely in memory and are used for communication between processes running on the same machine.
Distributed message queues: These can span multiple machines and are used for communication between processes running on different machines.
Persistent message queues: These can persist messages to disk, allowing them to survive system restarts or crashes.
Message queues are useful in a variety of scenarios…
Decoupling of components: such as for each component operating independently of the others.
Asynchronous processing: such as for background processing of long-running tasks.
Load balancing: such as for distributing workloads across multiple instances of an application.
Event-driven architectures: such as for where events are produced and consumed by different components.