Communication between Backend and Frontend via Microservice

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1

Hi all,

I’m working on a Cumulocity setup where I have a microservice that handles communication between frontend, and my application. Pushing updates from the application to the frontend through the microservice and viceversa. Has anyone tackled this in Cumulocity? I’d love to hear about your approaches or examples for enabling this kind of real-time communication.

Thanks!

2

I guess most of your requirements are covered in the WebSDK where you have a client, services and existing components to do that.

If you want to communicate with your microservice you need to use the client and implement the services yourself (in frontend and microservice).

Still, I don’t understand the real use cases behind it. Is it just data visualization? Why the communication through a microservice?

3

Hi,

Thanks for the response! Let me clarify my use case a bit more. The goal is to enable real-time, bidirectional communication in my Cumulocity setup. For example, I have a frontend (Angular) where a user might enter a configuration parameter in a textbox—say, a temperature threshold. This gets sent to a microservice (written in Java Spring), which then relays it to the backend application (connected devices also Java Spring). Conversely, the backend might receive updates from devices and send that through the microservice to push it to the frontend.

So, it’s not just about data visualization; it’s about facilitating a two-way communication: frontends ↔ microservice ↔ backends/devices. The microservice acts as a bridge to handle this communication and possibly add some logic or filtering along the way.
Does that sound like a reasonable approach? Are there specific components or examples in the WebSDK or Microservice SDK you’d recommend for this kind of setup? Maybe you’ve seen something similar implemented.

Thanks again!

4

What you are describing is something that can be achieved directly with Cumulocity without the need of having a microservice in between.

Angular has a 2-way data binding. Using the WebSDK you can directly send them to Cumulocity via the Service or client + provided API if desired.

For the other way around you also have services + API to subscribe on real-time updates of devices. So on every change in the database you receive a push message in the frontend you can visualize / process.

Microservices are only needed if you need custom backend logic that could not be implemented using the default Cumulocity API and services. For that communication pattern you are describing they are not necessary as supported out of the box.

Check out the codex I pasted in my last post.

5

Hi,

I agree, my example with the configuration parameter was an oversimplification. Right now, I’m still in a feasibility study phase, trying to piece together how everything could work in our Cumulocity setup. For example i can do simple get requests using @c8y/client FetchClient, but i am not sure how to push data with authentication from microservice to frontend.

However, in our case, we do need a microservice because we have custom logic that isn’t covered by the default Cumulocity API. For instance integration with external systems. So, the microservice isn’t just a pass-through, it’s adding value that we can’t achieve directly with Cumulocity’s standard features.

Given that, could you point me toward how to best set up the communication between the Angular frontend, the Java Spring microservice, and the backend/devices in a Cumulocity environment? Specifically:

  1. Communication Setup: Should I implement WebSockets/Server Side Events, or there a more Cumulocity-native way to handle this?
  2. Authentication: Since the microservice will need to interact with frontend/backend (and possibly Cumulocity’s API too), how should I handle authentication?
  3. Real-Time Updates: For pushing updates from the microservice to the frontend, would you recommend using Cumulocity’s real-time channels (e.g., via the SDK), or should I set up a direct WebSocket connection between the microservice and frontend?

Thanks again

6
  1. Just use the webSDK realtime subscription
  2. Use Tenant Options to save credentials for external systems. Check out role functionality for microservices General aspects - Cumulocity documentation
  3. Use standard Cumulocity objects like events or operations to communicate your changes to the frontend. E.g.: Create an even in your microservice subscribe the UI via WebSDK to the event type and update the UI accordingly.

Hope That helps!

Kind regards, Marco