description: converts the message from `string` to `int` and writes it into the `key`; the value is capped to the bounds of the specified type, e.g. `[0, 128]` in case of `set_u8`
-`get_str` - **get string value**
request: `REQUEST/get_str/NS/KEY`
response: `RESPONSE/get_str/NS/KEY`
topic: `REQUEST/get_str/NS/KEY`
description: returns the stored `string` value
-`get_strlen` - **get string length**
request: `REQUEST/get_strlen/NS/KEY`
response: `RESPONSE/get_strlen/NS/KEY`
topic: `REQUEST/get_strlen/NS/KEY`
description: returns the length of a stored `string` value