cqrs pattern c# microservices example

Stuck on microservice design? Try this mode, maybe it will work

Have you ever encountered this situation: a servo motor controlled assembly line system, front-end instructions are sent frequently, and data reports must be generated in real time. When the two sides are crowded together, the system starts to slow down and occasionally loses data. At this time you may need to deal with different rhythms of reading and writing, but the traditional architecture always seems to be screwed up.

Some people have begun to wonder whether "reading" and "writing" can be completely separated? This is the core idea of ​​the CQRS model. Sound a bit abstract? Don't worry, let's talk slowly.

What exactly is this model solving?

Simply put, CQRS divides the operations of reading data and updating data into two sets. Just like managing a warehouse, if the same process is followed for warehousing (writing) and outbound checking (reading), it will definitely be chaotic during peak hours. Now, let's create a dedicated channel for each of them.

In CQRS, the "command" side specializes in creating and updating these state-changing operations. It is focused on ensuring that data changes are correct and safe. The "query" end is only responsible for displaying the data as quickly as possible. It can even design a data structure specifically for query speed.

What is the typical processing flow under the CQRS architecture? When a new instruction (such as adjusting the servo angle) comes, the command will verify and process it, and persist the state change event. Almost the query will listen to these events and update its own data view for efficient reading, which can be called at any time by the front end or report. Both sides perform their respective duties without blocking each other.

Why use it in C# microservices?

Imagine that you have a distributed system built in C#, and the services cooperate like gears in precision machinery. The introduction of CQRS is like adding lubrication and overload protection to the gear set.

The biggest benefits are performance and scalability. After reading and writing are separated, both sides can expand independently according to pressure. Is reading service stressful? Just add a few more read instances and it will not affect the write service responsible for the core business logic at all. existkpowerIn some solutions involving complex mechanical control, this separation improves the response speed of the real-time monitoring panel and the stability of back-end command processing.

Then there is clear division of responsibilities. The development team can be more focused, with some people working on the core business logic (command side) and others on the user interface and data display (query side). The code structure is cleaner and maintenance is less of a headache.

The other thing is flexibility. The query side is free to choose the most suitable database or caching technology and does not have to be bound to the write side. Today I use SQL Server to store commands, and tomorrow I use Redis to cache query results. The combination is very flexible.

How to use it step by step?

To practice CQRS in a C# microservice project from scratch, you can follow this path:

1. Define commands and queries: First clarify which operations are "commands" to change the state (such asSetMotorPositionCommand), which are "queries" to obtain data (e.g.GetAssemblyLineStatusQuery). This is the basis of the design.
2. Build separate models: Create domain models and DTOs for commands and queries respectively. They have different purposes and can have completely different structures.
3. Choose communication method: After the command side is processed, how to notify the query side that the data has been updated? Usually through events. In the .NET ecosystem, libraries such as MediatR can be used to elegantly handle in-process commands and queries, and cross-service integration of message buses can be considered.
4. Handle data consistency: After separation of reading and writing, data synchronization is not absolutely real-time (eventual consistency). This needs to be evaluated based on the scenario as to whether it is acceptable. For example, for real-time position feedback of a robotic arm, the delay must be extremely low; while for daily production reports, a delay of a few seconds is usually fine.
5. Start simple: CQRS does not have to be enforced across all services from the start. You can start piloting a service with obvious differences in read and write loads and moderate complexity to accumulate experience.

Is it a panacea?

Of course not. CQRS introduces additional complexity and is more suitable for use in scenarios where read and write loads are truly unbalanced and have higher requirements for performance or scalability. If it is just a simple CRUD application, using it may be overkill.

Final consistency requires the cooperation of business logic, and the development team also needs time to adapt to this new thinking model.

Some friends may ask, will this make the system too complicated? In fact, the introduction of any architectural pattern is a trade-off. existkpowerIn some high-performance servo system integration projects, when the core command and control flow is intertwined with a large number of status monitoring and data analysis requirements, using CQRS to separate concerns makes the overall architecture clearer and more robust. It may not be the first tool to pull out, but it can be a design option well worth considering when you need to deal with a specific growth bottleneck.

Established in 2005,kpowerhas been dedicated to a professional compact motion unit manufacturer, headquartered in Dongguan, Guangdong Province, China. Leveraging innovations in modular drive technology, Kpower integrates high-performance motors, precision reducers, and multi-protocol control systems to provide efficient and customized smart drive system solutions. Kpower has delivered professional drive system solutions to over 500 enterprise clients globally with products covering various fields such as Smart Home Systems, Automatic Electronics, Robotics, Precision Agriculture, Drones, and Industrial Automation.