Node client for the Salesforce Pub/Sub API

See the official Pub/Sub API repo and the documentation for more information on the Salesforce gRPC-based Pub/Sub API.

• v4 to v5 Migration
• v4 Documentation
• Installation and Configuration
  • Authentication
    • User supplied authentication
    • Username/password flow
    • OAuth 2.0 client credentials flow (client_credentials)
    • OAuth 2.0 JWT bearer flow
  • Logging
• Quick Start Example
• Other Examples
  • Publish a platform event
  • Subscribe with a replay ID
  • Subscribe to past events in retention window
  • Work with flow control for high volumes of events
  • Handle gRPC stream lifecycle events
• Common Issues
• Reference
  • PubSubApiClient
  • SubscribeCallback
  • SubscriptionInfo
  • EventParseError
  • Configuration

v4 to v5 Migration

[!WARNING] Version 5 of the Pub/Sub API client introduces a couple of breaking changes which require a small migration effort. Read this section for an overview of the changes.

Configuration and Connection

In v4 and earlier versions of this client:

• you specify the configuration in a .env file with specific property names.
• you connect with either the connect() or connectWithAuth() method depending on the authentication flow.

In v5:

• you pass your configuration with an object in the client constructor. The .env file is no longer a requirement, you are free to store your configuration where you want.
• you connect with a unique connect() method.

Event handling

In v4 and earlier versions of this client you use an asynchronous EventEmitter to receive updates such as incoming messages or lifecycle events:

// Subscribe to account change events
const eventEmitter = await client.subscribe(
    '/data/AccountChangeEvent'
);

// Handle incoming events
eventEmitter.on('data', (event) => {
    // Event handling logic goes here
}):

In v5 you use a synchronous callback function to receive the same information. This helps to ensure that events are received in the right order.

const subscribeCallback = (subscription, callbackType, data) => {
    // Event handling logic goes here
};

// Subscribe to account change events
await client.subscribe('/data/AccountChangeEvent', subscribeCallback);

Installation and Configuration

Install the client library with npm install salesforce-pubsub-api-client.

Authentication

Pick one of these authentication flows and pass the relevant configuration to the PubSubApiClient constructor:

• User supplied authentication
• Username/password flow (recommended for tests)
• OAuth 2.0 client flow
• OAuth 2.0 JWT Bearer flow (recommended for production)

User supplied authentication

If you already have a Salesforce client in your app, you can reuse its authentication information. In the example below, we assume that sfConnection is a connection obtained with jsforce

const client = new PubSubApiClient({
    authType: 'user-supplied',
    accessToken: sfConnection.accessToken,
    instanceUrl: sfConnection.instanceUrl,
    organizationId: sfConnection.userInfo.organizationId
});

Username/password flow

[!WARNING] Relying on a username/password authentication flow for production is not recommended. Consider switching to JWT auth for extra security.

const client = new PubSubApiClient({
    authType: 'username-password',
    loginUrl: process.env.SALESFORCE_LOGIN_URL,
    username: process.env.SALESFORCE_USERNAME,
    password: process.env.SALESFORCE_PASSWORD,
    userToken: process.env.SALESFORCE_TOKEN
});

OAuth 2.0 client credentials flow (client_credentials)

const client = new PubSubApiClient({
    authType: 'oauth-client-credentials',
    loginUrl: process.env.SALESFORCE_LOGIN_URL,
    clientId: process.env.SALESFORCE_CLIENT_ID,
    clientSecret: process.env.SALESFORCE_CLIENT_SECRET
});

OAuth 2.0 JWT bearer flow

This is the most secure authentication option. Recommended for production use.

// Read private key file
const privateKey = fs.readFileSync(process.env.SALESFORCE_PRIVATE_KEY_FILE);

// Build PubSub client
const client = new PubSubApiClient({
    authType: 'oauth-jwt-bearer',
    loginUrl: process.env.SALESFORCE_JWT_LOGIN_URL,
    clientId: process.env.SALESFORCE_JWT_CLIENT_ID,
    username: process.env.SALESFORCE_USERNAME,
    privateKey
});

Logging

The client uses debug level messages so you can lower the default logging level if you need more information.

The documentation examples use the default client logger (the console). The console is fine for a test environment but you'll want to switch to a custom logger with asynchronous logging for increased performance.

You can pass a logger like pino in the client constructor:

import pino from 'pino';

const config = {
    /* your config goes here */
};
const logger = pino();
const client = new PubSubApiClient(config, logger);

Quick Start Example

Here's an example that will get you started quickly. It listens to up to 3 account change events. Once the third event is reached, the client closes gracefully.

1. Activate Account change events in Salesforce Setup > Change Data Capture.

2. Install the client and dotenv in your project:

   npm install salesforce-pubsub-api-client dotenv

3. Create a .env file at the root of the project and replace the values:

   SALESFORCE_LOGIN_URL=...
   SALESFORCE_USERNAME=...
   SALESFORCE_PASSWORD=...
   SALESFORCE_TOKEN=...

4. Create a sample.js file with the following content:

   import * as dotenv from 'dotenv';
   import PubSubApiClient from 'salesforce-pubsub-api-client';
   
   async function run() {
       try {
           // Load config from .env file
           dotenv.config();
   
           // Build and connect Pub/Sub API client
           const client = new PubSubApiClient({
               authType: 'username-password',
               loginUrl: process.env.SALESFORCE_LOGIN_URL,
               username: process.env.SALESFORCE_USERNAME,
               password: process.env.SALESFORCE_PASSWORD,
               userToken: process.env.SALESFORCE_TOKEN
           });
           await client.connect();
   
           // Prepare event callback
           const subscribeCallback = (subscription, callbackType, data) => {
               if (callbackType === 'event') {
                   // Event received
                   console.log(
                       `${subscription.topicName} - ``Handling ${event.payload.ChangeEventHeader.entityName} change event ` +
                           `with ID ${event.replayId} ` +
                           `(${subscription.receivedEventCount}/${subscription.requestedEventCount} ` +
                           `events received so far)`
                   );
                   // Safely log event payload as a JSON string
                   console.log(
                       JSON.stringify(
                           event,
                           (key, value) =>
                               /* Convert BigInt values into strings and keep other types unchanged */
                               typeof value === 'bigint'
                                   ? value.toString()
                                   : value,
                           2
                       )
                   );
               } else if (callbackType === 'lastEvent') {
                   // Last event received
                   console.log(
                       `${subscription.topicName} - Reached last of ${subscription.requestedEventCount} requested event on channel. Closing connection.`
                   );
               } else if (callbackType === 'end') {
                   // Client closed the connection
                   console.log('Client shut down gracefully.');
               }
           };
   
           // Subscribe to 3 account change event
           client.subscribe('/data/AccountChangeEvent', subscribeCallback, 3);
       } catch (error) {
           console.error(error);
       }
   }
   
   run();

5. Run the project with node sample.js

   If everything goes well, you'll see output like this:

   Connected to Salesforce org https://pozil-dev-ed.my.salesforce.com (00D58000000arpqEAA) as grpc@pozil.com
   Connected to Pub/Sub API endpoint api.pubsub.salesforce.com:7443
   /data/AccountChangeEvent - Subscribe request sent for 3 events

   At this point, the script is on hold and waits for events.

6. Modify an account record in Salesforce. This fires an account change event.

   Once the client receives an event, it displays it like this:

   /data/AccountChangeEvent - Received 1 events, latest replay ID: 18098167
   /data/AccountChangeEvent - Handling Account change event with ID 18098167 (1/3 events received so far)
   {
       "replayId": 18098167,
       "payload": {
           "ChangeEventHeader": {
           "entityName": "Account",
           "recordIds": [
               "0014H00002LbR7QQAV"
           ],
           "changeType": "UPDATE",
           "changeOrigin": "com/salesforce/api/soap/58.0;client=SfdcInternalAPI/",
           "transactionKey": "000046c7-a642-11e2-c29b-229c6786473e",
           "sequenceNumber": 1,
           "commitTimestamp": 1696444513000,
           "commitNumber": 11657372702432,
           "commitUser": "00558000000yFyDAAU",
           "nulledFields": [],
           "diffFields": [],
           "changedFields": [
               "LastModifiedDate",
               "BillingAddress.City",
               "BillingAddress.State"
           ]
           },
           "Name": null,
           "Type": null,
           "ParentId": null,
           "BillingAddress": {
               "Street": null,
               "City": "San Francisco",
               "State": "CA",
               "PostalCode": null,
               "Country": null,
               "StateCode": null,
               "CountryCode": null,
               "Latitude": null,
               "Longitude": null,
               "Xyz": null,
               "GeocodeAccuracy": null
           },
           "ShippingAddress": null,
           "Phone": null,
           "Fax": null,
           "AccountNumber": null,
           "Website": null,
           "Sic": null,
           "Industry": null,
           "AnnualRevenue": null,
           "NumberOfEmployees": null,
           "Ownership": null,
           "TickerSymbol": null,
           "Description": null,
           "Rating": null,
           "Site": null,
           "OwnerId": null,
           "CreatedDate": null,
           "CreatedById": null,
           "LastModifiedDate": 1696444513000,
           "LastModifiedById": null,
           "Jigsaw": null,
           "JigsawCompanyId": null,
           "CleanStatus": null,
           "AccountSource": null,
           "DunsNumber": null,
           "Tradestyle": null,
           "NaicsCode": null,
           "NaicsDesc": null,
           "YearStarted": null,
           "SicDesc": null,
           "DandbCompanyId": null
       }
   }

   Note that the change event payloads include all object fields but fields that haven't changed are null. In the above example, the only changes are the Billing State, Billing City and Last Modified Date.

   Use the values from ChangeEventHeader.nulledFields, ChangeEventHeader.diffFields and ChangeEventHeader.changedFields to identify actual value changes.

Other Examples

Publish a platform event

Publish a Sample__e Platform Event with a Message__c field:

const payload = {
    CreatedDate: new Date().getTime(), // Non-null value required but there's no validity check performed on this field
    CreatedById: '005_________', // Valid user ID
    Message__c: { string: 'Hello world' } // Field is nullable so we need to specify the 'string' type
};
const publishResult = await client.publish('/event/Sample__e', payload);
console.log('Published event: ', JSON.stringify(publishResult));

Subscribe with a replay ID

Subscribe to 5 account change events starting from a replay ID:

await client.subscribeFromReplayId(
    '/data/AccountChangeEvent',
    subscribeCallback,
    5,
    17092989
);

Subscribe to past events in retention window

Subscribe to the 3 earliest past account change events in the retention window:

await client.subscribeFromEarliestEvent(
    '/data/AccountChangeEvent',
    subscribeCallback,
    3
);

Work with flow control for high volumes of events

When working with high volumes of events you can control the incoming flow of events by requesting a limited batch of events. This event flow control ensures that the client doesn’t get overwhelmed by accepting more events that it can handle if there is a spike in event publishing.

This is the overall process:

1. Pass a number of requested events in your subscribe call.
2. Handle the lastevent callback type from subscribe callback to detect the end of the event batch.
3. Subscribe to an additional batch of events with client.requestAdditionalEvents(...). If you don't request additional events at this point, the gRPC subscription will close automatically (default Pub/Sub API behavior).

The code below illustrate how you can achieve event flow control:

try {
    // Connect with the Pub/Sub API
    const client = new PubSubApiClient(/* config goes here */);
    await client.connect();

    // Prepare event callback
    const subscribeCallback = (subscription, callbackType, data) => {
        if (callbackType === 'event') {
            // Logic for handling a single event.
            // Unless you request additional events later, this should get called up to 10 times
            // given the initial subscription boundary.
        } else if (callbackType === 'lastEvent') {
            // Last event received
            console.log(
                `${eventEmitter.getTopicName()} - Reached last requested event on channel.`
            );
            // Request 10 additional events
            client.requestAdditionalEvents(eventEmitter, 10);
        } else if (callbackType === 'end') {
            // Client closed the connection
            console.log('Client shut down gracefully.');
        }
    };

    // Subscribe to a batch of 10 account change event
    await client.subscribe('/data/AccountChangeEvent', subscribeCallback 10);
} catch (error) {
    console.error(error);
}

Handle gRPC stream lifecycle events

Use callback types from subscribe callback to handle gRPC stream lifecycle events:

const subscribeCallback = (subscription, callbackType, data) => {
    if (callbackType === 'grpcStatus') {
        // Stream status update
        console.log('gRPC stream status: ', status);
    } else if (callbackType === 'error') {
        // Stream error
        console.error('gRPC stream error: ', JSON.stringify(error));
    } else if (callbackType === 'end') {
        // Stream end
        console.log('gRPC stream ended');
    }
};

Common Issues

TypeError: Do not know how to serialize a BigInt

If you attempt to call JSON.stringify on an event you will likely see the following error:

TypeError: Do not know how to serialize a BigInt

This happens when an integer value stored in an event field exceeds the range of the Number JS type (this typically happens with commitNumber values). In this case, we use a BigInt type to safely store the integer value. However, the BigInt type is not yet supported in standard JSON representation (see step 10 in the BigInt TC39 spec) so this triggers a TypeError.

To avoid this error, use a replacer function to safely escape BigInt values so that they can be serialized as a string (or any other format of your choice) in JSON:

// Safely log event as a JSON string
console.log(
    JSON.stringify(
        event,
        (key, value) =>
            /* Convert BigInt values into strings and keep other types unchanged */
            typeof value === 'bigint' ? value.toString() : value,
        2
    )
);

Reference

PubSubApiClient

Client for the Salesforce Pub/Sub API

PubSubApiClient(configuration, [logger])

Builds a new Pub/Sub API client.

close()

Closes the gRPC connection. The client will no longer receive events for any topic.

async connect() → {Promise.<void>}

Authenticates with Salesforce then connects to the Pub/Sub API.

Returns: Promise that resolves once the connection is established.

async getConnectivityState() → Promise<connectivityState>}

Get connectivity state from current channel.

Returns: Promise that holds the channel's connectivity state.

async publish(topicName, payload, [correlationKey]) → {Promise.<PublishResult>}

Publishes a payload to a topic using the gRPC client.

Returns: Promise holding a PublishResult object with replayId and correlationKey.

async subscribe(topicName, subscribeCallback, [numRequested])

Subscribes to a topic.

async subscribeFromEarliestEvent(topicName, subscribeCallback, [numRequested])

Subscribes to a topic and retrieves all past events in retention window.

async subscribeFromReplayId(topicName, subscribeCallback, numRequested, replayId)

Subscribes to a topic and retrieves past events starting from a replay ID.

requestAdditionalEvents(topicName, numRequested)

Request additional events on an existing subscription.

SubscribeCallback

Callback function that lets you process incoming Pub/Sub API events while keeping track of the topic name and the volume of events requested/received.

The function takes three parameters:

Callback types:

SubscriptionInfo

Holds the information related to a subscription.

EventParseError

Holds the information related to an event parsing error. This class attempts to extract the event replay ID from the event that caused the error.

Configuration

Check out the authentication section for more information on how to provide the right values.