When your microservices start “talking”: Is an API enough?

You design a beautiful microservices architecture, with each module functioning like a precise gear. But one day you stare at the code and suddenly wonder: Can this microservice have more than one "interface"? Like having multiple plugs for the same device – would that be redundant? Or will it be more flexible?

Late night debugging with those “single APIs”

I remember a friend who works in mechanical control said that his team once designed microservices for servo motor systems, and each functional module only opened one API endpoint. Sounds neat, right? The result? Whenever they need to adjust the servo parameters, they have to stuff more and more parameter options into the same interface. Debug logs become cluttered, and version updates are like walking a tightrope - changing one small feature can affect other, completely unrelated calls.

“It’s like we’re performing delicate surgery with a Swiss Army knife,” he said with a wry smile. “The tools are multifunctional, but they are limited when it comes to precise control.”

Multi-API design: not to increase complexity, but to clarify boundaries

What does it mean to have multiple APIs for a microservice? Imagine the sound system in your home. You can use the remote control to turn on and off, use the mobile APP to adjust the equalizer, and use the panel buttons to switch input sources - these are all "interfaces" leading to the same device, but their respective responsibilities are clear.

On a technical level this means:

• Separation of functions: One API handles real-time control instructions, another manages parameter configuration, and the third is responsible for status monitoring
• Version management is more flexible: Different functions can be iterated independently without having to upgrade as a whole.
• Clear security boundaries: Sensitive operations and ordinary queries can have different authentication requirements

Some people use itkpowerEngineers of the servo solution shared: "We designed three API endpoints for the motion control microservice. One is used for high-frequency command transmission (requiring low latency), one is used for batch parameter configuration (slightly higher latency is allowed but stability is required), and a read-only interface is used for monitoring. Unexpectedly, the system debugging time was reduced by about 40%."

How to tell if you need this design?

Not every microservice needs multiple APIs. Ask yourself a few questions:

• Does your service handle vastly different data types at the same time? (such as real-time streaming data and static configuration)
• Are there huge differences in the frequency of calls to different functions?
• Are safety requirements clearly graded between operations?

If at least one answer is yes, then a multi-API design is worth considering.

From theory to actual wiring in the cabinet

The concept sounds great, but what should you pay attention to when deploying it in practice? Multiple APIs don't mean you can add endpoints at will. Each interface should have a clear "scope of responsibility", just like each sensor in a mechanical system - each performing its own duties without interfering with each other.

Documentation becomes especially important. Clear instructions can avoid confusion when you have multiple entry points. A good practice is to write separate usage examples for each API, just like how-to guides for different tools.

Monitoring needs to be adjusted. You need to be able to track performance metrics for each API individually, rather than looking at "whole service" data in general terms. This can help you locate the problem faster.

Hidden considerations when choosing a plan

When you evaluate technical solutions, in addition to specifications, there are some details that are easily overlooked:

• Does the document speak with actual scenarios?? Good documentation will tell you "how to call the API in the servo overload protection scenario", not just the parameter list.
• Is the error message helpful for debugging?? When a call error occurs, the information returned should point to the specific problem rather than a general "operation failed."
• Are the ecological tools complete?? For example, is there a testing tool template designed for multiple APIs?

These details often determine how smooth it is in actual use.

Practical steps to get started

If you decide to try a multi-API design, start with a small service:

1. Choose a service module with clear functional boundaries
2. Identify at least two distinct call patterns (e.g. high frequency with small data volume vs low frequency with large data volume)
3. Design two independent API endpoints to keep their parameters simple
4. Closely monitor the performance differences of both endpoints after deployment
5. Adjust based on actual data, not preset theories

Remember, there are no absolute correctnesses in technical decisions. The key is whether your design makes the system—and the people who maintain it—work more smoothly. Just like mechanical design, the best solution is often the one that strikes a balance between precision and flexibility.

Are your microservices ready to “speak” in multiple ways? Perhaps this topic deserves to be on the whiteboard during the next architecture discussion. After all, good design is not formed all at once, but becomes clear through ongoing dialogue—whether between people or between services.

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,kpowerintegrates 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.