RabbitMQ is widely used in scenarios where messages must be transmitted and processed efficiently and reliably. Common industries and business scenarios are shown as follows.
l E-commerce: Manages orders and inventories, payment notifications and other logistics-related messages.
l Financial services: Processes real-time transaction data, notifications and quotes, and supports asynchronous communication between financial institutions.
l Telecommunications: Handles the recording of telephone calls, the distribution of SMS and multimedia messages.
l Logistics and supply chain management: Tracks the location and status of goods and coordinates messaging across the supply chain.
l Social media: Supports real-time messaging push, chat and notification functions, as well as user-generated content.
l Game development: Deals with multi-player interactions in games, messaging and collaboration between players.
l Science and research: Processes distributed computing, task queues and data streaming.
RabbitMQ applies to application decoupling, load shifting/peak clipping, asynchronous communication and other scenarios.
System Decoupling
RabbitMQ reduces the coupling between applications and improves system flexibility and scalability. The following shows some examples of decoupling applications using RabbitMQ:
l Order and inventory management system: Assume that you have an online store and use an order system to receive and process orders, and an inventory management system to track inventory and update its status. With RabbitMQ, the order system sends order information to a message queue called "order_queue", and the inventory management system listens to the queue and updates the inventory upon receiving the order message. This way, the order system and the inventory management system can be decoupled for independent extension and maintenance.
l Log processing system: In a large-scale distributed system, each service generates a large number of logs. RabbitMQ works as an intermediary agent for log messages to uniformly manage and analyze these logs. In RabbitMQ, each service sends its log messages to a message queue called "log_queue", and the log processing system consumes the log messages and processes and stores them accordingly. This way, each service log can be processed independently without affecting each other.
l Traffic control system: Multiple service instances may be running at the same time in a micro-services architecture. If one service instance is overloaded, traditional load balancers cannot effectively control traffic distribution. RabbitMQ implements message-based traffic control. Each service instance sends its current load information to a message queue called "load_queue". A load controller subscribes to the queue and dynamically adjusts traffic distribution based on the load of individual service instances. This way, traffic control can be decoupled at the application level.
Load Shifting/Peak Clipping
RabbitMQ is an open-source message broker that supports many different message protocols and provides powerful messaging capabilities. In RabbitMQ, you can manage the rate and load of message delivery through load shifting/peak clipping.
l Load shifting: Load shifting refers to limiting the transmission rate of the message, so that the sending and receiving of messages can be within a controllable range. For example, suppose there is a message queue that can only process a maximum of 1,000 messages per second. When the sending rate of a message exceeds this limit, the message will be temporarily cached until the message queue can process more messages.
l Peak clipping: Peak clipping refers to adjusting the rate of message delivery, so that the sending and receiving of messages can adapt to the system load. For example, during peak hours, the system load may be very high, and if you continue to send messages at the same rate, the system may crash. Therefore, peak clipping can reduce the sending rate of messages and avoid overloading the system.
For example, suppose there is an online shopping website, and users need to generate an order message and send it to RabbitMQ after placing an order. To avoid system crash caused by excessive order volume, the following strategies can be adopted:
l Load shifting: Set the maximum number of orders processed by RabbitMQ per second to 1,000. When the user's order speed exceeds 1,000 orders per second, the system will temporarily cache the orders until the system can process more.
l Peak clipping: During certain time periods, such as promotions, order volumes are expected to be very high. In order to avoid overloading the system, you can adjust the maximum number of orders processed by RabbitMQ to 500 per second, that is, reduce the message sending rate, so that the system can better process orders.
In this way, the rate and load of message delivery can be effectively managed while ensuring system stability.
Asynchronous Communication
RabbitMQ is a messaging middleware that can be used for asynchronous communication. In the user registration scenario, RabbitMQ can be used to send and receive registration related messages.
Below is an asynchronous user registration process:
1. The user submits the registration form.
2. After receiving the registration request, the server writes the data submitted by the user to the database and generates a unique user ID.
3. The server encapsulates the user ID into a message and sends it to the registration queue of RabbitMQ.
4. Messages in the registration queue are listened to by one or more consumers.
5. After receiving the registration message, the consumer executes the registration related logic, such as sending confirmation email and generating user account.
6. After completing the registration logic, the consumer can encapsulate the result into a message and send it to another queue, such as sending a registration success notification to the user.
7. Messages in another queue can be listened to by one or more consumers, and responsible for processing the logic of successful registration notification.
Implementing asynchronous user registration with RabbitMQ provides the following benefits:
l Decoupling: By decoupling the registration request from the registration logic, the dependencies between system components can be reduced.
l Asynchronous processing: Instead of waiting for the registration logic to complete, the user can immediately return a successful response. The real registration logic can be completed in the background, which improves the concurrency of the system.
l Scalability: By adding more consumers to process the registration message, you can easily increase the throughput of your system.
l Reliability: RabbitMQ has the ability to persist messages so that they are not lost even in the event of a failure.
It should be noted that using RabbitMQ for asynchronous communication requires processing the reliability of the message, such as using a transaction or message confirmation mechanism, to ensure that the message can be processed successfully.