Platform Events

• Platform Events Architecture
• Event Object
• Demo - Publishing events via API
• Demo - Subscribing to events via Process Builder
• Demo - Subscribing to events using CometD in Lightning Component

Platform Events Architecture

Platform Events Components

• Provides an event-driven messaging architecture to enable apps to communicate inside and outside of Salesforce
• Consists of event producers, event consumers, and channel (Event Bus)
• Publishers and subscribers communicate with each other through events
• One or more subscribers can listen to the same event and carry out actions

Quiz - 1

• Channel and Event Bus are the same thing?

Sliding Window

Sliding window is 24 hours (now, may change)

Event Object Types

1. Standard Events
• AssetTokenEvent (Represents an event associated with an asset token, such as token issuance and registration of a connected device as an Asset)
• OrgLifecycleNotification
2. Change Events
   • Change Data Capture (create, update, delete)
   • Example: Sync Heroku Postgres data with Org data
   • Notes about Change Data Capture
3. Custom Events
   • Entities with suffix: __e

Sample Event Object

Notification with custom field: Message

Event object - special kind of entity

• It is different from Standard and Custom objects.
• An event message is an instance of a platform event, similar to how a record is an instance of a standard/custom object
• Update or delete event records not allowed
• Can’t view event records in the Salesforce UI and don’t have page layouts
• Deleting a platform event definition will result in permanent deletion
• Event definition and all events in the topic are deleted
• You can grant permissions to users in profiles or in permission sets

Event object - special kind of entity - contd.

• Events are in their own transaction. So if you publish from apex, it cannot be rolled back, but the publish is a transaction
• The allOrNoneHeader API header is ignored when publishing platform events through the API.
• The Apex setSavepoint() and rollback() Database methods aren’t supported with platform events.
• DML limits and other Apex governor limits apply for publishing platform events

Quiz - 2

• Can we view event records in the Salesforce UI ?

Custom field types supported

• Checkbox
• Date
• Date/Time
• Number
• Text
• Text Area (Long)

Quiz - 3

• Field type Checkbox is supported for Event Object?

ReplayId System Field

• Identifies a platform event record
• Used to get stored events that are within the retention window
• The subscribed CometD client can retrieve past events using the ReplayId field
• The ReplayId is unique for the org and the channel (Event Bus)
• Similar to Kafka's offset
• Notes about Apache Kafka

Publishing Event Message with Apex

           // Call method to publish events (pubEvents)
           List results = EventBus.publish(pubEvents);
       

Publishing Event Message with API

POST to the Endpoint: /services/data/v41.0/sobjects/Event_Name__e/
In our case, Event_Name__e is Notification__e

Sample request payload:

            { "Message__c" : "Power Off" }
          

Publishing Event Message with API - Demo

Subscribe to Event Message with Process Builder

Subscribe to Event Message with Process Builder - contd.

Subscribe to Event Message with Process Builder - contd.

Subscribe to Event Message with Process Builder - contd.

Subscribe to Event Message with Process Builder - contd.

Note we are using Email Alert as the action for the event received

Subscribe to Event Message with Process Builder - contd.

Email Template Setup

Email Alert Setup

Email Alert - result of Event Subscription Action

Subscribe Event Message with cometD

Channel Name: /event/Event_Name__e/

cometD Endpoint: /cometd/41.0

Sample response payload:

            { "data": {
                  "schema": "dffQ2QLzDNHqwB8_sHMxdA",
                  "payload": {
                    "CreatedDate": "2017-26-11T18:31:40Z",
                    "CreatedById": "005D0000001cSZs",
                    "Message__c": "Power Off"
                  },
                  "event": { "replayId": 2 }
                },
                "channel": "/event/Notification__e"
              }
          

Subscribe Event Message with cometD - Example

Subscribe Event Message with cometD - Demo

Subscribe Event Message with cometD - Demo - event payload

Resources for demo

• Demo code: Components and Server-side Controller
• Trailhead: Build an Instant Notification App
• Platform Events Developer Guide
• SFDX Platform Events

About CometD

Implemention of Bayeux protocol

Supported Methods

• connect
• disconnect
• handshake
• subscribe
• unsubscribe

Bayeux

• Protocol for transporting asynchronous messages
• Primarily over web protocols such as HTTP and WebSocket
• With low latency between a web server and web clients
• Supports responsive bidirectional interactions between web client and the web server using AJAX

References

• Bayeux Protocol Specification 1.0
• Bayeux Protocol, CometD, and Long Polling

Platform Event Limits

Video:Platform Events: Inside and Out