What is Message Queuing (mq)?

The producer first passes the message to a container called a queue, and then takes the message from this container and forwards it to the consumer.

Message Queuing is Microsoft's message processing technology, which provides message processing and message queuing functions for any application in any combination of computers with Microsoft Windows installed, regardless of whether these computers are on the same network or online at the same time.

A message queuing network is any group of computers that can send messages to each other. Different computers in the network play different roles in ensuring the smooth processing of messages. Some of them provide routing information to determine how to send messages, some keep important information of the whole network, and some just send and receive messages.

Introduction of message queue types:

At present, there are two main types of message queues: POSIX message queue and system V message queue, which are widely used at present. Each message queue has a queue header, which is described by the structure msg_queue. The queue header contains a lot of information about the message queue. Including message queue key value, user ID, group ID, number of messages in message queue, etc.

Message queue is a linked list of messages, which can be regarded as a record with a specific format and a specific priority. A process with write permission to the message queue can add new messages to the message queue according to some rules; A process with read access to the message queue can read messages from the message queue. Message queuing is persistent in the kernel.