Change Data Capture Developer Guide

Change Data Capture
Keep Your External Data Current with Change Data Capture
Change Event Message Structure
Merged Change Events
Other Types of Change Events: Gap and Overflow Events
Subscribe to Change Events
Change Event Storage and Delivery
Subscription Channels
Compose Streams of Change Data Capture Notifications with Custom Channels
Example Diagrams for Channels and Channel Members
Transaction-Based Replication Steps
Subscribe with Pub/Sub API
Subscribe with CometD Using the EMP Connector Sample
Get Compound Fields in Change Events
Enrich Change Events with Extra Fields
Filter Your Event Streams
Subscribe with Apex Triggers
Monitor Change Event Publishing and Delivery Usage
Security Considerations
Change Event Considerations
Standard Object Notes
Change Events for Fields
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Subscribe with CometD Using the EMP Connector Sample

Salesforce provides a connector to CometD that subscribes to streaming events. The EMP connector sample is a thin wrapper around the CometD library and simplifies subscribing to data change events in Java. The tool subscribes to a channel, receives notifications, and supports replaying events with durable streaming.

EMP Connector is a free, open-source, community-supported tool. Salesforce provides this tool as an example of how to subscribe to events using CometD. To contribute to the EMP Connector project with your own enhancements, submit pull requests to the repository at https://github.com/forcedotcom/EMP-Connector.

Important

Prerequisites:

Steps:

  1. To get a local copy of the EMP-Connector GitHub repository: 
    1$ git clone https://github.com/forcedotcom/EMP-Connector.git
  2. To build the EMP-Connector tool, enter these commands: 
    1$ cd EMP-Connector
2$ mvn clean package
    The generated JAR file includes the connector and the DevLoginExample functionality. The shaded JAR contains all the dependencies for the connector, so you don’t have to download them separately. The JAR file has a -phat Maven classifier.
  3. Run this command. 
    1$ java -classpath 
2target/emp-connector-0.0.1-SNAPSHOT-phat.jar com.salesforce.emp.connector.example.DevLoginExample https://MyDomainName.my.salesforce.com <username> <password> <channel>

    For a sandbox, replace https://MyDomainName.my.salesforce.com with https://MyDomainName--SandboxName.sandbox.my.salesforce.com.

    If you’re not using enhanced domains, your sandbox My Domain URLs are different. You can find your org’s My Domain login URL on the My Domain Setup page.

    Note

    For <channel>, use the channel to subscribe to. For example, /data/ChangeEvents.