salesforce-pubsub-api-client

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.

• Installation and Configuration
  • User supplied authentication
  • Username/password flow
  • OAuth 2.0 client credentials flow (client_credentials)
  • OAuth 2.0 JWT bearer flow
• Basic 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
  • Use a custom logger
• Reference
  • PubSubApiClient
  • PubSubEventEmitter
  • EventParseError

Installation and Configuration

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

Create a .env file at the root of the project for configuration.

Pick one of these authentication flows and fill the relevant configuration:

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

[!TIP] The default client logger is fine for a test environment but you'll want to switch to a custom logger with asynchronous logging for increased performance.

User supplied authentication

If you already have a Salesforce client in your app, you can reuse its authentication information. You only need this minimal configuration:

SALESFORCE_AUTH_TYPE=user-supplied

PUB_SUB_ENDPOINT=api.pubsub.salesforce.com:7443

When connecting to the Pub/Sub API, use the following method instead of the standard connect() method to specify authentication information:

await client.connectWithAuth(accessToken, instanceUrl, 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.

SALESFORCE_AUTH_TYPE=username-password
SALESFORCE_LOGIN_URL=https://login.salesforce.com
SALESFORCE_USERNAME=YOUR_SALESFORCE_USERNAME
SALESFORCE_PASSWORD=YOUR_SALESFORCE_PASSWORD
SALESFORCE_TOKEN=YOUR_SALESFORCE_USER_SECURITY_TOKEN

PUB_SUB_ENDPOINT=api.pubsub.salesforce.com:7443

OAuth 2.0 client credentials flow (client_credentials)

SALESFORCE_AUTH_TYPE=oauth-client-credentials
SALESFORCE_LOGIN_URL=YOUR_DOMAIN_URL
SALESFORCE_CLIENT_ID=YOUR_CONNECTED_APP_CLIENT_ID
SALESFORCE_CLIENT_SECRET=YOUR_CONNECTED_APP_CLIENT_SECRET

PUB_SUB_ENDPOINT=api.pubsub.salesforce.com:7443

OAuth 2.0 JWT bearer flow

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

SALESFORCE_AUTH_TYPE=oauth-jwt-bearer
SALESFORCE_LOGIN_URL=https://login.salesforce.com
SALESFORCE_CLIENT_ID=YOUR_CONNECTED_APP_CLIENT_ID
SALESFORCE_USERNAME=YOUR_SALESFORCE_USERNAME
SALESFORCE_PRIVATE_KEY_FILE=PATH_TO_YOUR_KEY_FILE

PUB_SUB_ENDPOINT=api.pubsub.salesforce.com:7443

Basic Example

Here's an example that will get you started quickly. It listens to a single account change event.

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

2. Create a sample.js file with this content:

   import PubSubApiClient from 'salesforce-pubsub-api-client';
   
   async function run() {
       try {
           const client = new PubSubApiClient();
           await client.connect();
   
           // Subscribe to account change events
           const eventEmitter = await client.subscribe(
               '/data/AccountChangeEvent'
           );
   
           // Handle incoming events
           eventEmitter.on('data', (event) => {
               console.log(
                   `Handling ${event.payload.ChangeEventHeader.entityName} change event ` +
                       `with ID ${event.replayId} ` +
                       `on channel ${eventEmitter.getTopicName()} ` +
                       `(${eventEmitter.getReceivedEventCount()}/${eventEmitter.getRequestedEventCount()} ` +
                       `events received so far)`
               );
               console.log(JSON.stringify(event, null, 2));
           });
       } catch (error) {
           console.error(error);
       }
   }
   
   run();

3. 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 as [e-mail]
   Connected to Pub/Sub API endpoint api.pubsub.salesforce.com:7443
   Topic schema loaded: /data/AccountChangeEvent
   Subscribe request sent for 100 events from /data/AccountChangeEvent...
   

   At this point the script will be on hold and will wait for events.

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

   Once the client receives an event, it will display it like this:

   Received 1 events, latest replay ID: 18098167
   Handling Account change event with ID 18098167 on channel /data/AccountChangeEvent (1/100 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:

const eventEmitter = await client.subscribeFromReplayId(
    '/data/AccountChangeEvent',
    5,
    17092989
);

Subscribe to past events in retention window

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

const eventEmitter = await client.subscribeFromEarliestEvent(
    '/data/AccountChangeEvent',
    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 event from PubSubEventEmitter 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();
    await client.connect();

    // Subscribe to a batch of 10 account change event
    const eventEmitter = await client.subscribe('/data/AccountChangeEvent', 10);

    // Handle incoming events
    eventEmitter.on('data', (event) => {
        // Logic for handling a single event
    });

    // Handle last requested event
    eventEmitter.on('lastevent', () => {
        console.log(
            `Reached last requested event on channel ${eventEmitter.getTopicName()}.`
        );
        // Request 10 additional events
        client.requestAdditionalEvents(eventEmitter, 10);
    });
} catch (error) {
    console.error(error);
}

Handle gRPC stream lifecycle events

Use the EventEmmitter returned by subscribe methods to handle gRPC stream lifecycle events:

// Stream end
eventEmitter.on('end', () => {
    console.log('gRPC stream ended');
});

// Stream error
eventEmitter.on('error', (error) => {
    console.error('gRPC stream error: ', JSON.stringify(error));
});

// Stream status update
eventEmitter.on('status', (status) => {
    console.log('gRPC stream status: ', status);
});

Use a custom logger

The client logs output to the console by default but you can provide your favorite logger in the client constructor.

When in production, asynchronous logging is preferable for performance reasons.

For example:

import pino from 'pino';

const logger = pino();
const client = new PubSubApiClient(logger);

Reference

PubSubApiClient

Client for the Salesforce Pub/Sub API

PubSubApiClient([logger])

Builds a new Pub/Sub API client.

Name	Type	Description
logger	Logger	an optional custom logger. The client uses the console if no value is supplied.

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 connectWithAuth(accessToken, instanceUrl, organizationIdopt) → {Promise.<void>}

Connects to the Pub/Sub API with user-supplied authentication.

Returns: Promise that resolves once the connection is established.

Name	Type	Description
accessToken	string	Salesforce access token
instanceUrl	string	Salesforce instance URL
organizationId	string	optional organization ID. If you don't provide one, we'll attempt to parse it from the accessToken.

async publish(topicName, payload, correlationKeyopt) → {Promise.<PublishResult>}

Publishes a payload to a topic using the gRPC client.

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

Name	Type	Description
topicName	string	name of the topic that we're subscribing to
payload	Object
correlationKey	string	optional correlation key. If you don't provide one, we'll generate a random UUID for you.

async subscribe(topicName, [numRequested]) → {Promise.<EventEmitter>}

Subscribes to a topic.

Returns: Promise that holds an EventEmitter that allows you to listen to received events and stream lifecycle events.

Name	Type	Description
topicName	string	name of the topic that we're subscribing to
numRequested	number	optional number of events requested. If not supplied or null, the client keeps the subscription alive forever.

async subscribeFromEarliestEvent(topicName, [numRequested]) → {Promise.<EventEmitter>}

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

Returns: Promise that holds an EventEmitter that allows you to listen to received events and stream lifecycle events.

Name	Type	Description
topicName	string	name of the topic that we're subscribing to
numRequested	number	optional number of events requested. If not supplied or null, the client keeps the subscription alive forever.

async subscribeFromReplayId(topicName, numRequested, replayId) → {Promise.<EventEmitter>}

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

Returns: Promise that holds an EventEmitter that allows you to listen to received events and stream lifecycle events.

Name	Type	Description
topicName	string	name of the topic that we're subscribing to
numRequested	number	number of events requested. If null, the client keeps the subscription alive forever.
replayId	number	replay ID

requestAdditionalEvents(eventEmitter, numRequested)

Request additional events on an existing subscription.

Name	Type	Description
eventEmitter	PubSubEventEmitter	event emitter that was obtained in the first subscribe call
numRequested	number	number of events requested.

PubSubEventEmitter

EventEmitter wrapper for processing incoming Pub/Sub API events while keeping track of the topic name and the volume of events requested/received.

The emitter sends the following events:

Event Name	Event Data	Description
data	Object	Client received a new event. The attached data is the parsed event data.
error	EventParseError | Object	Signals an event parsing error or a gRPC stream error.
lastevent	void	Signals that we received the last event that the client requested. The stream will end shortly.
keepalive	{ latestReplayId: number, pendingNumRequested: number }	Server publishes this keep alive message every 270 seconds (or less) if there are no events.
end	void	Signals the end of the gRPC stream.
status	Object	Misc gRPC stream status information.

The emitter also exposes these methods:

Method	Description
getRequestedEventCount()	Returns the number of events that were requested when subscribing.
getReceivedEventCount()	Returns the number of events that were received since subscribing.
getTopicName()	Returns the topic name for this subscription.
getLatestReplayId()	Returns the replay ID of the last processed event or null if no event was processed yet.

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.

Name	Type	Description
message	string	The error message.
cause	Error	The cause of the error.
replayId	number	The replay ID of the event at the origin of the error. Could be undefined if we're not able to extract it from the event data.
event	Object	The un-parsed event data at the origin of the error.
latestReplayId	number	The latest replay ID that was received before the error.