Device Service SDK hack to forward a message to a another Service

[waas1919]

Good morning

I've been looking at the Device Service SDK in C and have a very general question related to this.
I've seen the examples provided and it seems that, by default, once a device service gets new data from a "sensor" it pushes it to the core-data.
This time, and also based on the answer given by @lenny-intel on this question #128 , I wanted to know what could the best approach for the following scenario:

• I have a device service that generates random numbers (So, no necessarily images or any heavy loads)
• I want to increment the random numbers in another service (let's call it IncrementService on the port 59876)
• After increment the number, I want now to push it to the core-data

I see the following options for this, and would like to know which one you advise, or if none, all comments are very welcome.

[Option 1]

• Hack into the device service sdk to force pushing the messages to the IncrementService on the port 59876.
• For all data that the IncrementService receives, it will increment the number and finally push data to the core-data

[Option 2]

• Change the configuration.toml of the device service where we would change the Port to be IncrementService on the port 59876

[Clients]
  [Clients.core-data]
  Protocol = 'http'
  Host = 'localhost'
  Port = 59876 # Previously was 59880

• This case maybe we would receive in our IncrementService all the output from this device service.
• For all data that the IncrementService receives, it will increment the number and finally push data to the core-data

Question:
As I am asking this, it seems a bit hacky these previous options. I feel I am not really using the best practice here.
Is there any other option, for instance, using the methods from the Device Service SDK in C where I can force the data to be forwarded into some other port, and not the core-data? And then using the core-data API, after processing I could simply do a POST to the core-data?
What is your advice?

Thank you!

[waas1919]

Maybe my question is a bit confusing. What I would like to know is that if it's possible to use the device-sdk-c to send messages to some other server (could be even a python http server outside of EdgeX)?
In this example:
https://github.com/edgexfoundry/device-sdk-c/blob/main/src/c/examples/counters/device-counter.c#LL126C9-L126C17

This is sending the counter data directly to core-data. It is possible to send the data elsewhere?

Thanks

[lenny-goodell]

@waas1919 , why wouldn't the device service itself increment the number.

Note that Core Data is optional persistence of Event/Reading data. Device services publish Event/Reading data to the EdgeX MessageBus for other services (App, Rules Engine, Core Data) to consume.

A custom app service is most appropriate for transforming data (app-Increment) and publishing it back to the EdgeX MessageBus for other services (other App, Rules Engine, Core Data) to consume.