Crate umari

Expand description

§ESRuntime SDK

SDK for building event-sourced command handlers as WASM modules.

§Overview

This crate provides the traits and types needed to write command handlers that run in the ESRuntime. Command handlers:

Declare which events they need to read (via EventSet)
Declare which domain IDs to query (via CommandInput)
Rebuild state from historical events (via apply)
Make decisions and emit new events (via handle)

§Example

use rive_core::prelude::*;
use serde::Deserialize;
use my_schema::{OpenedAccount, SentFunds};

#[derive(EventSet)]
enum Query {
    OpenedAccount(OpenedAccount),
    SentFunds(SentFunds),
}

#[derive(CommandInput, Deserialize)]
struct Input {
    #[domain_id("account_id")]
    account_id: String,
    amount: f64,
}

#[derive(Default)]
struct Withdraw {
    balance: f64,
}

impl Command for Withdraw {
    type Query = Query;
    type Input = Input;

    fn apply(&mut self, event: Query) {
        match event {
            Query::OpenedAccount(ev) => self.balance = ev.initial_balance,
            Query::SentFunds(ev) => self.balance -= ev.amount,
        }
    }

    fn handle(self, input: Input) -> Result<Emit, CommandError> {
        if self.balance < input.amount {
            return Err(CommandError::rejected("Insufficient funds"));
        }
         
        Ok(Emit::new().event(SentFunds {
            account_id: input.account_id,
            amount: input.amount,
            recipient_id: None,
        }))
    }
}

#[tokio::main]
async fn main() -> anyhow::Result<()> {
    let client = UmaDBClient::new("http://0.0.0.0:50051".to_string())
        .connect_async()
        .await?,

    Withdraw::execute(&client, Input {
        account_id: "bob".to_string(),
        amount: 14.50,
    }).await?;

    Ok(())
}