@connectrpc/connect-express NPM

@connectrpc/connect-express

Connect is a family of libraries for building and consuming APIs on different languages and platforms, and @connectrpc/connect brings type-safe APIs with Protobuf to TypeScript.

@connectrpc/connect-express provides a middleware for Express, the fast, unopinionated, minimalist web framework for Node.js

expressConnectMiddleware()

Adds your Connect RPCs to an Express server.

// connect.ts
import { ConnectRouter } from "@connectrpc/connect";

export default function(router: ConnectRouter) {
  // implement rpc Say(SayRequest) returns (SayResponse)
  router.rpc(ElizaService, ElizaService.methods.say, async (req) => ({
    sentence: `you said: ${req.sentence}`,
  }));
}

// server.ts
import http from "http";
import express from "express";
+ import routes from "connect";
+ import { expressConnectMiddleware } from "@connectrpc/connect-express";

const app = express();

+ app.use(expressConnectMiddleware({
+  routes
+ }));

http.createServer(app).listen(8080);

With that server running, you can make requests with any gRPC-web or Connect client.

curl with the Connect protocol:

curl \
    --header "Content-Type: application/json" \
    --data '{"sentence": "I feel happy."}' \
    http://localhost:8080/connectrpc.eliza.v1.ElizaService/Say

Node.js with the gRPC-web protocol (using a transport from @connectrpc/connect-node):

import { createPromiseClient } from "@connectrpc/connect";
import { createGrpcWebTransport } from "@connectrpc/connect-node";
import { ElizaService } from "./gen/eliza_connect.js";

const transport = createGrpcWebTransport({
  baseUrl: "http://localhost:8080",
  httpVersion: "1.1",
});

const client = createPromiseClient(ElizaService, transport);
const { sentence } = await client.say({ sentence: "I feel happy." });
console.log(sentence) // you said: I feel happy.

A client for the web browser actually looks identical to this example - it would simply use createConnectTransport from @connectrpc/connect-web instead.

Note that support for gRPC is limited, since many gRPC clients require HTTP/2, and Express does not support the Node.js http2 module.