ioFog SDK
The ioFog SDK is an optional library. It provides an easy way for your edge nodes to communicate with each other without needing to handle the complex discovery process yourself.
If you don't need to communicate directly between your fog nodes, you might not need the SDK. But if you do, you still have options!
Under the hood, the SDK uses the Agent Local API which, while more low-level, is considered a public API you can call directly too.
Many languages (like Rust, Haskell, etc) have a Foreign Function Interface (FFI) that will allow you to use the C SDK.
Alternatively, you might be able to abstract your node-to-node communication into a purpose-built microservice in one of the languages above.
For example, let's say you wanted to use Ruby for most of your service development. You could write a small microservice in JavaScript using the SDK and have it make requests on behalf of your Ruby microservice.