Common usage scenarios of message queues in PHP

Message queue MQ is essentially a queue. Its simplest operation is to join and dequeue. It determines when and what conditions to join the queue and when and what conditions to deque according to the program. In other words, if you encounter a scenario where the business requirements of the enqueuing system and the dequeuing system are inconsistent, you can consider whether to use message queues to implement it. There are many applicable scenarios. Here are a few common scenarios and explanations.

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1: Asynchronous processing, application decoupling, distributed

Scenario: The processing results of the main business on the sub-business are not the same When you care.

Case: The relationship between the order system, logistics system, financial system and operation log recording system in the e-commerce system.

Popular explanation: Xiao Ming is a cake shop assistant. After he made the cake, he put it in the window, marked "completed" on the corresponding order, and then continued to make the next cake. He didn't care how or when the cake was sold.
Implementation: Use a queue middleware or middle system to store the common parts of several business systems and process them independently. The processing progress of each system can be recorded using its own independent tag. After all systems have completed operations, perform dequeuing operations or persist data storage.

Note: The disaster recovery capability of intermediate data needs to be considered to ensure that the business process can be restored when a failure occurs and is recovered. Ensure that every piece of data can be processed correctly.

2: Peak processing

Scenario: Traffic is unbalanced at various time points

Case: flash sale, Rush Buy

Explanation: Xiao Ming takes a long time to make cakes. After the order comes, he first registers it into a list, and then makes it one by one in order. When the order quantity is too large, a "Sold Out" sign will be temporarily displayed. .

Implementation: Use single-threaded tools to queue business requirements. When the business request reaches the threshold, a friendly prompt is given and the user's request is rejected.

Notes: For peak demand, you can post prompts such as "Temporarily unavailable for purchase, please wait" during peak periods to prevent the impact of traffic on subsequent business. For needs such as flash sales that stop as soon as they are available, the issue of over-issuance needs to be considered. You can add a quota counter, or issue a flash sale completion mark when the flash sale quota is full. After the subsequent processing program detects the completion mark, subsequent processing will be performed.

3: Delivery Guarantee

Scenario: The content needs to be strictly executed one by one, and the execution is guaranteed to be successful. When the execution is unsuccessful or interrupted, you can Recovery

Case: Banking and financial systems, systems that need to improve disaster recovery capabilities

Explanation: The cake made by Xiao Ming needs to be inspected and signed by the customer before he can continue to make the next cake.

Implementation: After the queuing system writes the business requirements into the message queue, it will proceed to the next business processing. The subsequent processing program processes the queue contents one by one, and issues a "Complete Permit" after the processing is completed. The content in the message queue can only be deleted from the message queue after obtaining the "Complete Permission".

Note: Focus on issues related to disaster recovery, such as business recovery issues and repeated processing issues.

Four: Sorting Guarantee

Scenario: The content in the message queue has a strict order.

Case: Queuing and waiting system

Explanation: Xiao Ming needs to strictly follow the order of making cakes.

Implementation: The queuing system writes the contents into the message queue one by one, arranges them in a single line, and extracts the data in a first-in, first-out order for subsequent processing.

Note: You need to use a single thread to ensure there is only one production line.

5: Scalability

Scenario: When using publish-subscribe mode, add new subscribers
Case: After registering a user , in the model of sending successful SMS, add a function of sending email
Implementation: Multiple consumers subscribe to the middle layer of a message, and then the publisher publishes the information to the middle layer. Consumers who subscribe to this middle layer can receive this message and perform subsequent processing. in this structure. If you want to add a message subsequent processing component, you only need to subscribe this component to the middle layer.
Note: Ensure that there is no deep coupling between businesses to prevent interference during expansion.

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The above are several commonly used scenarios for message queues. Message queues can smooth out the differences between systems and improve system stability. There are many applicable scenarios.

When selecting the message queue medium, it is recommended that students do not have to maximize the conditions and goals at the beginning. What conditions must be used to perfectly solve the problem? The program still requires long-term maintenance and optimization process.

Although the performance degradation of Redis is still very serious when the traffic is high and a large amount of persistent data is required, it is still recommended that you learn queues from Redis. In the course, you only understand the application of queues by changing the process. Scenarios and ideas, any online project is constantly optimized and improved. If you want to solve all problems perfectly through a set of videos, I’m sorry that I can’t do it. The needs and application scenarios of each job are different, so there are different It will be improved according to specific needs when needed.

When judging the queue demand, you need to add a counter field when judging the application of queue conditions. Judge the length of the current queue each time it is pushed into the queue. If the number exceeds the limited flash sale number, it will not enter the queue program.

In actual use, there is no need to deliberately pursue where message queues need to be added. Instead, it should be reasonably selected and used according to the actual situation when conducting business separation and decoupling, as well as some special demands.

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