Service invocation with the JavaScript SDK on Dapr Docs

How to: Call services with the JavaScript SDK

Mon, 01 Jan 0001 00:00:00 +0000

DaprClient.invoker.invoke() sends a request through the caller’s sidecar to a target application. These examples use @dapr/dapr 3.19.0 or later. Follow the receiving invocations guide to start the invocation-service target used below.

Invoke an application over HTTP

Save this complete example as client.mjs:

import { DaprClient, HttpMethod } from "@dapr/dapr";

async function main() {
 const client = new DaprClient({
 daprHost: "127.0.0.1",
 daprPort: "3501",
 });

 try {
 const response = await client.invoker.invoke(
 "invocation-service",
 "orders",
 HttpMethod.POST,
 { orderId: "101", quantity: 2 },
 { headers: { "X-Correlation-ID": "order-101" } },
 );
 console.log(response);
 } finally {
 await client.stop();
 }
}

main().catch((error) => {
 console.error(error);
 process.exitCode = 1;
});

In another terminal, run the caller with its own sidecar:

How to: Receive service invocations with the JavaScript SDK

Mon, 01 Jan 0001 00:00:00 +0000

Use DaprServer.invoker.listen(methodName, callback, options?) to register an invocation handler. These examples use @dapr/dapr 3.19.0 or later.

Start an HTTP service

Save this complete example as server.mjs:

import { DaprServer, HttpMethod } from "@dapr/dapr";

async function main() {
 const server = new DaprServer({
 serverHost: "127.0.0.1",
 serverPort: "3000",
 clientOptions: {
 daprHost: "127.0.0.1",
 daprPort: "3500",
 },
 });

 await server.invoker.listen(
 "orders",
 async (request) => {
 if (!request.body) {
 throw new Error("An order request body is required");
 }
 const order = JSON.parse(request.body);
 console.log("Received order:", order);
 console.log("Correlation ID:", request.headers?.["x-correlation-id"]);
 return { orderId: order.orderId, status: "accepted" };
 },
 { method: HttpMethod.POST },
 );

 await server.invoker.listen("health", async () => ({ healthy: true }));
 await server.start();

 async function stop() {
 await server.stop();
 await server.client.stop();
 }

 process.once("SIGINT", () => {
 stop().catch((error) => {
 console.error(error);
 process.exitCode = 1;
 });
 });
}

main().catch((error) => {
 console.error(error);
 process.exitCode = 1;
});

Run the service and its sidecar:

Service invocation configuration and usage

Mon, 01 Jan 0001 00:00:00 +0000

This guidance applies to @dapr/dapr 3.19.0 or later. See calling services and receiving invocations for complete application examples.

Client lifetime

Reuse a long-lived DaprClient instead of creating one per invocation. Await outstanding work before calling await client.stop() during application shutdown. If using DaprServer, call await server.stop() to stop its listener, then await server.client.stop() to close its embedded client’s resources. Stopping the server alone does not stop that client.

The client initializes its connection and waits for the sidecar when first used. You can call await client.start() to check readiness before accepting application traffic. This connects to an existing sidecar; it does not launch the Dapr runtime process.