Custom Broadcast Logic

Sometimes you want a WASM module to actively push notifications directly to the Admin HUD without storing permanent state. You can do this using the qos_sdk::broadcast module.

#Low Stock Alerts

Building upon the Inventory module, we can dispatch a critical alert to the manager's dashboard if a SKU drops below 5 items.

src/lib.rs

#![no_std]

// Assuming the qos_sdk has a broadcast module:
use qos_sdk::{state, output, broadcast, LogLevel};

#[no_mangle]
pub extern "C" fn run() -> i32 {
    let sku_key = "inventory:sku_beer";
    
    if let Some(val) = state::get(sku_key) {
        if val.len() == 4 {
            let mut buf = [0u8; 4];
            buf.copy_from_slice(&val);
            let mut stock = u32::from_le_bytes(buf);
            
            if stock > 0 {
                stock -= 1;
                state::set(sku_key, &stock.to_le_bytes()).unwrap();
                
                // --- NEW LOGIC HERE ---
                if stock == 5 {
                    broadcast::send(LogLevel::Warn, b"Beer stock is critically low! Only 5 left.");
                }
                
                output::write(b"{\"status\":\"success\"}");
                return 0;
            }
        }
    }
    
    1
}

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