Client

Pre-requisites

• Dapr CLI installed
• Initialized Dapr environment
• Latest LTS version of Node or greater

Installing and importing Dapr’s JS SDK

Install the SDK with npm:

npm i dapr-client

Import the libraries:

import { DaprClient, DaprServer, HttpMethod, CommunicationProtocolEnum } from "dapr-client";
const daprHost = "127.0.0.1"; // Dapr Sidecar Host
const daprPort = "3500"; // Dapr Sidecar Port of this Example Server
const serverHost = "127.0.0.1"; // App Host of this Example Server
const serverPort = "50051"; // App Port of this Example Server 
// HTTP
const server = new DaprServer(serverHost, serverPort, daprHost, daprPort); 
const client = new DaprClient(daprHost, daprPort);
// GRPC 
const server = new DaprServer(serverHost, serverPort, daprHost, daprPort, CommunicationProtocolEnum.GRPC);
const client = new DaprClient(daprHost, daprPort, CommunicationProtocolEnum.GRPC);

Running

To run the examples, you can use two different protocols to interact with the Dapr sidecar: HTTP (default) or gRPC.

Using HTTP (default)

import { DaprClient, DaprServer } from "dapr-client";
const client = new DaprClient(daprHost, daprPort);
const server= new DaprServer(appHost, appPort, daprHost, daprPort);

# Using dapr run
dapr run --app-id <example-sdk> --app-port 50051 --app-protocol http npm run start
# or, using npm script
npm run start:dapr-http

Using gRPC

Since HTTP is the default, you will have to adapt the communication protocol to use gRPC. You can do this by passing an extra argument to the client or server constructor.

import { DaprClient, DaprServer, CommunicationProtocol } from "dapr-client";
const client = new DaprClient(daprHost, daprPort, CommunicationProtocol.GRPC);
const server= new DaprServer(appHost, appPort, daprHost, daprPort, CommunicationProtocol.GRPC);

# Using dapr run
dapr run --app-id <example-sdk> --app-port 50051 --app-protocol grpc npm run start
# or, using npm script
npm run start:dapr-grpc

DaprClient Library

A library that provides methods for how an application communicates with the Dapr sidecar.

DaprServer Library

A library for how an application registers bindings / routes with Dapr. The start() method is used to start the server and bind the routes.

Building blocks

The JavaScript SDK allows you to interface with all of the Dapr building blocks.

Invoke a service

import { DaprClient, HttpMethod } from "dapr-client"; 
const daprHost = "127.0.0.1"; 
const daprPort = "3500"; 
async function start() {
  const client = new DaprClient(daprHost, daprPort); 
  const serviceAppId = "my-app-id";
  const serviceMethod = "say-hello";
  // POST Request
  const response = await client.invoker.invoke(serviceAppId , serviceMethod , HttpMethod.POST, { hello: "world" });
  // GET Request
  const response = await client.invoker.invoke(serviceAppId , serviceMethod , HttpMethod.GET);
}

• For a full guide on service invocation visit How-To: Invoke a service.

Save, get and delete application state

import { DaprClient } from "dapr-client"; 
const daprHost = "127.0.0.1"; 
const daprPort = "3500"; 
async function start() {
  const client = new DaprClient(daprHost, daprPort); 
  const serviceStoreName = "my-state-store-name";
  // Save State
  const response = await client.state.save(serviceStoreName, [
    {
      key: "first-key-name",
      value: "hello"
    },
    {
      key: "second-key-name",
      value: "world"
    }
  ]);
  // Get State
  const response = await client.state.get(serviceStoreName, "first-key-name");
  // Get Bulk State
  const response = await client.state.getBulk(serviceStoreName, ["first-key-name", "second-key-name"]);
  // State Transactions
  await client.state.transaction(serviceStoreName, [
    {
      operation: "upsert",
      request: {
        key: "first-key-name",
        value: "new-data"
      }
    },
    {
      operation: "delete",
      request: {
        key: "second-key-name"
      }
    }
  ]);
  // Delete State
  const response = await client.state.delete(serviceStoreName, "first-key-name");
}

• For a full list of state operations visit How-To: Get & save state.

Publish & subscribe to messages

Publish messages

import { DaprClient } from "dapr-client"; 
const daprHost = "127.0.0.1"; 
const daprPort = "3500"; 
async function start() {
  const client = new DaprClient(daprHost, daprPort); 
  const pubSubName = "my-pubsub-name";
  const topic = "topic-a";
  const message = { hello: "world" }
  // Publish Message to Topic
  const response = await client.pubsub.publish(pubSubName, topic, message);
}

Subscribe to messages

import { DaprServer } from "dapr-client";
const daprHost = "127.0.0.1"; // Dapr Sidecar Host
const daprPort = "3500"; // Dapr Sidecar Port of this Example Server
const serverHost = "127.0.0.1"; // App Host of this Example Server
const serverPort = "50051"; // App Port of this Example Server "
async function start() {
  const server = new DaprServer(serverHost, serverPort, daprHost, daprPort);
  const pubSubName = "my-pubsub-name";
  const topic = "topic-a";
  // Configure Subscriber for a Topic
  await server.pubsub.subscribe(pubSubName, topic, async (data: any) => console.log(`Got Data: ${JSON.stringify(data)}`));
  await server.start();
}

• For a full list of state operations visit How-To: Publish & subscribe.

Interact with bindings

Output Bindings

import { DaprClient } from "dapr-client"; 
const daprHost = "127.0.0.1"; 
const daprPort = "3500"; 
async function start() {
  const client = new DaprClient(daprHost, daprPort); 
  const bindingName = "my-binding-name";
  const bindingOperation = "create";
  const message = { hello: "world" };
  const response = await client.binding.send(bindingName, bindingOperation, message);
}

Input Bindings

import { DaprServer } from "dapr-client";;
const daprHost = "127.0.0.1"; 
const daprPort = "3500"; 
const serverHost = "127.0.0.1";
const serverPort = "5051";
async function start() {
  const server = new DaprServer(serverHost, serverPort, daprHost, daprPort);;
  const bindingName = "my-binding-name";
  const response = await server.binding.receive(bindingName, async (data: any) => console.log(`Got Data: ${JSON.stringify(data)}`));
  await server.start();
}

• For a full guide on output bindings visit How-To: Use bindings.

Retrieve secrets

import { DaprClient } from "dapr-client"; 
const daprHost = "127.0.0.1"; 
const daprPort = "3500"; 
async function start() {
  const client = new DaprClient(daprHost, daprPort); 
  const secretStoreName = "my-secret-store";
  const secretKey = "secret-key";
  // Retrieve a single secret from secret store
  const response = await client.secret.get(secretStoreName, secretKey);
  // Retrieve all secrets from secret store
  const response = await client.secret.getBulk(secretStoreName);
}

• For a full guide on secrets visit How-To: Retrieve secrets.

Get configuration keys

import { DaprClient } from "dapr-client";
const daprHost = "127.0.0.1";
const daprAppId = "example-config";
async function start() {
  const client = new DaprClient(
    daprHost,
    process.env.DAPR_HTTP_PORT
  );
  const config = await client.configuration.get('config-store', ['key1', 'key2']);
  console.log(config); 
  console.log(JSON.stringify(config));
}
start().catch((e) => {
  console.error(e);
  process.exit(1);
});

Related links

• JavaScript SDK examples