ways of communication between microservices

When your mechanical device starts “talking”: the art of communication between microservices

Picture this: you design a sophisticated robotic arm. The servo motors of each joint respond perfectly, and the angle control of the steering gear is accurate to the nearest millimeter. But when you try to coordinate the entire system, you find that the arm movements are stuck, out of sync, and even "fight" occasionally. What's the problem? It is often not the problem with a single motor, but that the "dialogue" between them is confused. Just like mechanical parts need to work together, microservices in modern software architecture also need clear and reliable communication methods.

It's not just a matter of code, it's a matter of how a system "lives" and works together.

Why is communication between microservices easy to "drop the chain"?

In the past, many systems were like a unified mechanical assembly, with all logic bundled together. If a small gear is changed, the entire machine may need to be shut down for adjustment. The microservice architecture splits the system into many independent, small, and functionally focused units, just like modularizing complex machines into standard motors, sensors, and controllers. This brings flexibility and maintainability, but also introduces new challenges: How can these dispersed "small modules" exchange information efficiently, accurately, and stably?

Common situations are:

• Information is delayed or lost: One service sent an instruction, but the other did not receive it, or it took a long time to respond, causing the process to be interrupted.
• Data is inconsistent: Service A updates the status, but service B still operates with the old data, and the results are contradictory.
• Coupling too tight: The dependence between services is too deep. If one of them goes wrong, the chain reaction will bring down the entire system, and the meaning of "independence" of microservices will be lost.
• Difficult to trace: A problem occurs, but I don’t know which “conversation” the error occurred in. The troubleshooting is like spinning in a maze.

It's like you are giving instructions to a group of scattered mechanical units without using a unified communication protocol - some rely on gear transmission signals, some use air pressure transmission, and some even rely on flash lights. It would be strange if it is not chaotic.

Make conversations flow: Several core communication “languages”

How to make these microservices collaborate smoothly like a well-trained mechanical team? The key is choosing the right communication model. They are like different connectors or ways of transmitting signals.

1. Synchronous call: ask questions directly and wait for answers. The most common one is a request-response mode similar to HTTP API. Service A directly sends a request to Service B and waits for a clear reply before continuing its work. It's like pressing a button on a control panel and waiting until the light comes on or the motor rotates for feedback before proceeding to the next step.

• benefit: Simple and intuitive, with clear logic.
• need attention: If the other party's service is slow or hangs up, the caller will also be "stuck", easily causing the entire chain to wait. Suitable for scenarios with high real-time requirements and stable downstream services.

2. Asynchronous messages: Leave notes and process them individually through message queues (such as RabbitMQ, Kafka concept) or event buses. When service A completes something, it just publishes an event or message to a "message relay" and forgets about it. Services B and C that care about the event will obtain and process it themselves. This is like after a mechanical unit completes an action, it posts a completion note on the shared bulletin board. Other related units can look at it themselves and decide what to do.

• benefit: Complete decoupling, the sender does not rely on the real-time status of the receiver; it can buffer pressure and prevent the system from being overwhelmed by sudden requests.
• need attention: The architecture becomes complex, it is necessary to ensure reliable delivery of messages, and the order of event processing must be considered.

3. Publish/Subscribe: Broadcast notifications, everyone gets what they need. This is a common pattern of asynchronous messages. A service acts as a publisher, publishing events to a topic channel. Any service that subscribes to this topic will receive a copy. Just like the central broadcast system in the workshop, notifying "Part A is in place", all workstations that need this information can hear it at the same time and respond autonomously.

There is no absolute answer to which "language" to choose. It depends on the "personality" of your system: Do you need tight, instant fit, or do you value resiliency and throughput more? Many times, multiple modes are mixed in a system.

kpowerPerspective: Design communications like precision machinery

in uskpowerIn our experience of dealing with various hardware integration and motion control, we have found that communication between software microservices has a wonderful similarity with the coordination of a physical mechanical system. Reliability, real-time, fault tolerance - these requirements are common.

When we look at this problem, we will not just start from the purely software level. For example, how to ensure that messages are transmitted as stably as electrical signals? How to let the system continue to operate at a degraded level like a mechanical redundancy design when some units fail? How to monitor the flow of information, like using sensors to monitor the speed and torque of each drive shaft?

Thinking about a few simple questions may help you clarify your thinking:

• Do you need strict "action confirmation" between your services, or can you "trigger and forget"?
• How much impact will delays in information transmission have on business?
• If a service is temporarily down, should messages be queued or can they be ignored for the time being?

Let microservices communicate well. The goal is not to pursue the most fashionable technology, but to find the neural network that best suits the "physiological structure" of your system. It should make data flow as smooth as well-oiled bearings, allow services to be both independent and cooperative, and ultimately allow your entire application—whether it’s driving physical machinery or processing digital transactions—to run flexibly, robustly, and efficiently.

A good architecture is like a sophisticated machine in itself, and every communication detail deserves careful polishing. When you solve the problem of talking between services, you'll find that building complex and reliable systems suddenly becomes much clearer and more controllable.

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.