Streaming, Platform Events and CDC

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Overview

• https://developer.salesforce.com/docs/atlas.en-us.224.0.api_streaming.meta/api_streaming/event_comparison.htm

Terms

• https://developer.salesforce.com/docs/atlas.en-us.224.0.api_streaming.meta/api_streaming/terms.htm

• Pub / Sub

• Bayeux Protocol, CometD, and Long Polling

  • https://developer.salesforce.com/docs/atlas.en-us.224.0.api_streaming.meta/api_streaming/BayeauxProtocolAndCometD.htm

CometD client

• If the client receives events, the client must reconnect immediately using CometD to receive the next set of events. If the reconnection doesn't occur within 40 seconds, the server expires the subscription, and the connection closes.

• The maximum size of the HTTP request post body that the server can accept from the client is 32,768 bytes.

Streaming API

• Push technology - Pub / Sub model

• Near real-time stream of data, but asynchronous

• Can be used internally also

• Active connection must be maintained via long polling

• Steps

  • Push Topics are created

  • Client negotiates a connection

    • Login request and response

  • Handshake request

  • Connection request

  • Subscribe to a channel

  • Client waits for an event

  • No need for polling

  • Salesforce Broadcast changes

  • Client asks Salesforce to keep the connection open

• Concurrent limits (No. of long running calls) and total limits.

• Streaming API regularly validates the OAuth token or session ID while the client is connected.

• Durability is not guaranteed

Change Data Capture

• With Change Data Capture, you can receive changes of Salesforce records in real time and synchronize corresponding records in an external data store.

• Receive auto-published event notifications for Salesforce record changes

• Change Data Capture publishes events for changes in Salesforce records corresponding to create, update, delete, and undelete operations.

• The order of the fields in the JSON event message is not guaranteed.

• Standard or Custom Channels

• Single entity or multiple entities

• Create a custom channel if you have multiple subscribers and each subscriber receives change events from a different set of entities.

• Change Data Capture ignores sharing settings and sends change events for all records of a Salesforce object.

• To use CDC on Task and Event the external user must have View All Data to your entire system. Don’t do this! The External user must have View All for the object that is being tracked. See extra notes on permissions https://developer.salesforce.com/docs/atlas.en-us.change_data_capture.meta/change_data_capture/cdc_security_perms.htm

• See notes for encryption https://developer.salesforce.com/docs/atlas.en-us.change_data_capture.meta/change_data_capture/cdc_security_shield_encryption.htm