Considerations for Defining and Publishing Platform
Events
Take note of the considerations when defining and publishing
platform events.
Considerations for Defining Platform Events
Field-Level Security
All platform event fields are read only by default, and you can’t restrict access to a
particular field. Field-level security permissions don’t apply and the event message
contains all fields.
Enforcement of Field Attributes
Platform event records are validated to ensure that the attributes of their custom
fields are enforced. Field attributes include the Required and Default attributes, the
precision of number fields, and the maximum length of text fields.
Permanent Deletion of Event Definitions
When you delete an event definition, it’s permanently removed and can’t be restored.
Before you delete the event definition, delete the associated triggers. Published events
that use the definition are also deleted.
Renaming Event Objects
Before you rename an event, delete the associated triggers. If the event name is
modified after clients have subscribed to this event, the subscribed clients must
resubscribe to the updated topic. To resubscribe to the new event, add your trigger for
the renamed event object.
No Associated Tab
Platform events don’t have an associated tab because you can’t view event records in
the Salesforce user interface.
No SOQL Support
You can’t query event messages using SOQL.
No Record Page Support in Lightning App Builder
When creating a record page in Lightning App Builder, platform events that you defined
show up in the list of objects for the page. However, you can’t create a Lightning
record page for platform events because event records aren’t available in the user
interface.
Platform Events in Package Uninstall
When uninstalling a package with the option Save a copy of this package's
data for 48 hours after uninstall enabled, platform events aren’t
exported.
Event Volume in Package Installations and Upgrades
Installing a managed or unmanaged package that contains a standard-volume platform
event causes the event type to be saved as high volume in the subscriber org. Upgrading
a managed package doesn't change the event volume in the subscriber org.
No Support in Professional and Group Editions
Platform events aren’t supported in Professional and Group Edition orgs. Installation
of a package that contains platform event objects fails in those orgs.
Permissions for Defining and Using Platform Events
To define a custom platform event, you must have the Customize Application permission.
For the permissions for publishing and subscribing to platform events, see Platform Event Permissions.
Considerations for Publishing Platform Events
Publishing Events in Read-Only Mode
During read-only mode, publishing standard-volume platform events results in an
exception, and the events aren’t published. Publishing high-volume platform events in
read-only mode sometimes fails when the event schema isn’t up to date in Salesforce.
Your org is in read-only mode during Salesforce maintenance activities.
High-Volume Platform Event Persistence
Platform events are temporarily persisted to and served from an industry-standard
distributed system during the retention period. A distributed system doesn’t have the
same semantics or guarantees as a transactional database. As a result, we can’t provide
a synchronous response for an event publish request. Events are queued and buffered, and
Salesforce attempts to publish the events asynchronously. In rare cases, the event
message might not be persisted in the distributed system during the initial or
subsequent attempts. This means that the events aren’t delivered to subscribers, and
they aren’t
recoverable.
At-Least-Once Event Publishing and Duplicate Events
Asynchronous platform event publishing uses the at-least-once pub/sub model, not the
exactly-once model. With the at-least-once model, there’s a small chance of duplicate
events, because if the system encounters an internal error when publishing the queued
event, it retries the publishing. In rare cases, the system doesn't receive a publish
acknowledgment, so the same event is published more than once. However, if publish
acknowledgments are received as expected, no duplicate events are published.
A duplicate event is an event with the same EventUuid field value, a different ReplayId field value, and the same payload. We recommend you handle any
issues that result from duplicate events in your subscriber. For example, you can
implement deduplication logic using the EventUuid
value and avoid processing duplicate events.
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