Crate moleculer

Inspired and compatible with Moleculer JS

You can currently do all the basics of emit, broadcast and call.

However it only works with the NATS transporter and JSON serializer/deserializer.

Getting Started

Simple example showing how to receive an event, and responding to a request, for more check the examples folder.

use std::error::Error;
use serde::Deserialize;

use moleculer::{
    config::{ConfigBuilder, Transporter},
    service::{EventBuilder, Service, ActionBuilder},
    EventContext, ActionContext, ServiceBroker,
};

#[tokio::main]
async fn main() -> eyre::Result<()> {
    env_logger::init();
    color_eyre::install()?;

    // build config
    let config = ConfigBuilder::default().transporter(Transporter::nats("nats://localhost:4222"))
    .build();

    // create the first event
    let print_hi = EventBuilder::new("printHi").add_callback(print_hi).build();

    // create the second event
    let print_name = EventBuilder::new("printName")
        .add_callback(print_name)
        .build();

    // create math action
    let math_action = ActionBuilder::new("mathAdd").add_callback(math_add).build();

    // create a service with events and actions
    let greeter_service = Service::new("rustGreeter")
        .add_event(print_hi)
        .add_event(print_name)
        .add_action(math_action);

    // create service broker with service
    let service_broker = ServiceBroker::new(config).add_service(greeter_service);

    // start the service broker
    service_broker.start().await;

    Ok(())
}


// callback for first event, will be called whenever "printHi" event is received
fn print_hi(_ctx: EventContext) -> Result<(), Box<dyn Error>> {
    println!("Hello from Rust");
    Ok(())
}

// callback for second event, will be called whenever "printName" event is received
fn print_name(ctx: EventContext) -> Result<(), Box<dyn Error>> {
    let msg: PrintNameMessage = serde_json::from_value(ctx.params)?;

    println!("Hello to: {} from Rust", msg.name);

    Ok(())
}

// callback for math action
fn math_add(ctx: ActionContext) -> Result<(), Box<dyn Error>> {
    // get message decode using serde
    let msg: ActionMessage = serde_json::from_value(ctx.params.clone())?;
    let answer = msg.a + msg.b;

    // serialize reply using serde and send reply
    let _ = ctx.reply(answer.into());

    Ok(())
}

#[derive(Deserialize)]
struct PrintNameMessage {
    name: String,
}

#[derive(Deserialize)]
struct ActionMessage {
    a: i32,
    b: i32,
}

Modules

config

Create Config struct using ConfigBuilder with global settings for you micro-service.

service

Create Service struct with Events and Actions.

Structs

ServiceBroker

The struct used to interact with moleculer. Use emit(), broadcast() and call() functions.

Type Aliases

ActionContext

An alias to service::Context<service::Action>. Send a response to a request using reply().

EventContext

An alias to service::Context<service::Event>. In all contexts emit(), broadcast() and call() are available.