This page discusses ways you can integration Simple IoT into your system. At its core, SIOT is a distributed graph database optimized for storing, viewing, and synchronizing state/config in IoT systems. This makes it very useful for any system where you need distributed state/config.
With SIOT, you run the same application in both the cloud and edge devices, so you can use any of the available integration points at either place.
This primary way to interact with Simple IoT is through a NATS API. You can add additional processes written in any language that has a NATS client. Additionally, the NATS wire protocol is fairly simple so could be implemented from scratch if needed. If your most of your system is written in C++, but you needed a distributed config/state store, then run SIOT along side your existing processes and add a NATs connection to SIOT. If you want easy scripting in your system, consider writing a Python application that can read/modify the SIOT store over NATS.
The SIOT data structures are very general (nodes and points) arranged in a graph, so you can easily add your own data to the SIOT store by defining new node and point types as needed. This makes SIOT very flexible and adaptable to about any purpose. You can use points in a node to represent maps and arrays. If you data needs more structure, then nested nodes can accomplish that. It is important with SIOT data to retain CRDT properties. These concepts are discussed more in ADR-1.
The requirement to only use nodes and points may seem restrictive at first, but can be viewed as a serialization format with CRDT properties that are convenient for synchronization. Any distributed database requires meta data around your data to assist with synchronization. With SIOT, we have chosen to make this metadata simple and accessible to the user. It is typical to convert this data to more convenient data structures in your application -- much the same way you would deserialize JSON.
The architecture page discusses data structures in more detail.
If you need history and graphs, you can add InfluxDB and Grafana. This instantly gives you history and graphs of all state and configuration changes that happened in the system.
Simple IoT was designed with Embedded Linux systems in mind, so it is very efficient -- a single, statically linked Go binary with all assets embedded that is ~20MB in size and uses ~20MB of memory. There are no other dependencies required such as a runtime, other libraries, etc. This makes SIOT extremely easy to deploy and update. An Embedded Linux system deployed at the edge can be synchronized with a cloud instance using an sync connection.
MCUs are processors designed for embedded control and are typically 32-bit CPUs that run bare-metal code or a small OS like FreeRTOS or Zephyr and don't have as much memory as MPUs. MCUs cannot run the full SIOT application or easily implement a full data-centric data store. However, you can still leverage the SIOT system by using the node/point data structures to describe configuration and state and interacting with a Simple IoT like any other NATS client. nanopb can be used on MCUs to encode and decode protobuf messages, which is the default encoding for SIOT messages.
If your MCU supports MQTT, then it may make sense to use that to interact with Simple IoT as MQTT is very similar to NATS, and NATS includes a built-in MQTT server. The NATS wire protocol is also fairly simple and can also be implemented on top of any TCP/IP stack.
If your MCU interfaces with a local SIOT system using USB, serial, or CAN, then you can use the SIOT serial adapter.