Trait zenoh_flow_nodes::prelude::Source

pub trait Source: Node + Send + Sync {
    // Required method
    fn new<'async_trait>(
        context: Context,
        configuration: Configuration,
        outputs: Outputs
    ) -> Pin<Box<dyn Future<Output = Result<Self>> + Send + 'async_trait>>
       where Self: Sized + 'async_trait;
}

A Source feeds data into a data flow.

A Source only possesses Output (either typed or raw) as it does not receive any data from upstream nodes but from “outside” the data flow.

A structure implementing the Source trait typically needs to keep a reference to the Output.

Example

use async_trait::async_trait;
use zenoh_flow_nodes::prelude::*;

// Use our provided macro to expose the symbol that Zenoh-Flow will look for when it will load
// the shared library.
#[export_source]
pub struct MySource {
    output: Output<usize>,
    // The state could go in such structure.
    // state: Arc<Mutex<State>>,
}

#[async_trait::async_trait]
impl Source for MySource {
    async fn new(
        _context: Context,
        _configuration: Configuration,
        mut outputs: Outputs,
    ) -> Result<Self> {
        let output = outputs
            .take("out")
            .expect("No output called 'out' found")
            .typed(|buffer, data| todo!("Provide your serialiser here"));

        Ok(Self { output })
    }
}

#[async_trait::async_trait]
impl Node for MySource {
    async fn iteration(&self) -> Result<()> {
        // To mutate the state, first lock it.
        //
        // let state = self.state.lock().await;
        //
        // The state is a way for the Source to read information from the external world, i.e., interacting with
        // I/O devices.

        self.output.send(10usize, None).await
    }
}

Required Methods

fn new<'async_trait>( context: Context, configuration: Configuration, outputs: Outputs ) -> Pin<Box<dyn Future<Output = Result<Self>> + Send + 'async_trait>>

where Self: Sized + 'async_trait,

For a Context, a Configuration and a set of Outputs, produce a new Source.

Sources only possess Outputs as their purpose is to fetch data from the external world.

Implementors