SMDK - SmartModuleRecord
SmartModuleRecord is a wrapper on the standard Record, which provides extra details on the Record such as the moment when the Record was produced.
When building any type of SmartModules you will have access to each record, in
the SmartModule function these records are represented with the
SmartModuleRecord struct.
Consider the following SmartModule of type Map, which processes weather data:
use fluvio_smartmodule::{smartmodule, Result, SmartModuleRecord, RecordData};
#[smartmodule(map)]
pub fn map(record: &SmartModuleRecord) -> Result<(Option<RecordData>, RecordData)> {
let string = std::str::from_utf8(record.value.as_ref())?; // parses UTF-8 string from bytes
let feels_like = string.parse::<i32>()?; // attemps to parse the string value into a `i32`
let feels_like = feels_like.to_string(); // turs the integer into a string
Ok((key, feels_like.into())) // returs to the stream
}
For weather casting it would be helpful to also have access to the moment when the data was captured. We could have our wather value mapped to a string which also holds a timestamp.
use fluvio_smartmodule::{smartmodule, Result, SmartModuleRecord, RecordData};
#[smartmodule(map)]
pub fn map(record: &SmartModuleRecord) -> Result<(Option<RecordData>, RecordData)> {
let string = std::str::from_utf8(record.value.as_ref())?; // parses UTF-8 string from bytes
let feels_like = string.parse::<i32>()?; // attemps to parse the string value into a `i32`
- let feels_like = feels_like.to_string(); // turs the integer into a string
+ let feels_like_with_timestamp = format!("{}_{}", record.timestamp(), feels_like);
Ok((key, feels_like_with_timestamp.into())) // returs to the stream
}
With this small change we are injecting insightful data to our record. This is a simple use case but we can have more based on the implementation and business requirements.
