Backend

Express

Integrate Rivet with Express.js for Node.js web applications

Express.js is a popular Node.js web framework. Rivet integrates seamlessly with Express using middleware mounting.

View Example on GitHub

Check out the complete example

Installation

Install Express alongside Rivet:

Command Line

npm install express
npm install -D @types/express

Basic Setup

Create Your Registry

Set up your Rivet Actor:

TypeScript

// registry.ts
import { actor, setup } from "@rivetkit/actor";

export const counter = actor({
  state: { count: 0 },
  actions: {
    increment: (c, amount: number = 1) => {
      c.state.count += amount;
      c.broadcast("countChanged", c.state.count);
      return c.state.count;
    },
    getCount: (c) => c.state.count,
  },
});

export const registry = setup({
  use: { counter },
});

Integrate with Express

Mount Rivet into your Express application:

TypeScript

// server.ts
import { registry } from "./registry";
import express from "express";

// Start Rivet
const { client, handler } = registry.createServer();

// Setup Express app
const app = express();

// Enable JSON parsing
app.use(express.json());

// Mount Rivet handler
app.use("/registry", handler);

// Add your API routes
app.post("/increment/:name", async (req, res) => {
  const name = req.params.name;
  const { amount = 1 } = req.body;
  
  try {
    const counter = client.counter.getOrCreate([name]);
    const newCount = await counter.increment(amount);
    
    res.json({ success: true, count: newCount });
  } catch (error) {
    res.status(500).json({ 
      success: false, 
      error: error.message 
    });
  }
});

app.get("/count/:name", async (req, res) => {
  const name = req.params.name;
  
  try {
    const counter = client.counter.getOrCreate([name]);
    const count = await counter.getCount();
    
    res.json({ name, count });
  } catch (error) {
    res.status(500).json({ 
      success: false, 
      error: error.message 
    });
  }
});

app.listen(8080, () => {
  console.log("Server running at http://localhost:8080");
});