Understanding the Platform Event Error Handling Challenge
Platform events operate within a distributed system that doesn't provide the same guarantees as traditional transactional databases. Events are queued and published asynchronously, with no synchronous response mechanism. In rare cases, event messages might not be persisted properly, and no built-in mechanism surfaces these errors to publishers or consumers.This asynchronous nature creates unique challenges for error handling that differ from traditional Salesforce development patterns.
Causes of the Platform Event Errors
1. Persistence failures: In rare cases, event messages might not be persisted properly in the distributed system during initial or subsequent publish requests. 2. Uncatchable exceptions: When Apex limit exceptions occur in platform event triggers (like DML or SOQL exceptions), they can't be caught with traditional try-catch blocks, causing the code to fail and making the current batch of events unavailable. 3. Unhandled exceptions: If a non-limit exception occurs in your trigger and isn't caught, the trigger stops execution and unprocessed events from the batch won't be available again. 4. Subscriber failures: When subscriber Apex fails to complete processing an event, there needs to be a mechanism to retry or monitor these failures.How to Handle the Platform Event Errors
1. Implement Robust Platform Event Triggers
Write robust triggers that are resilient when exceptions occur. A key feature to leverage is thesetResumeCheckpoint method, which allows triggers to resume execution after uncatchable exceptions.
apextrigger OrderEventTrigger on Order_Event__e (after insert) { // Set checkpoint for the first event EventBus.TriggerContext.currentContext().setResumeCheckpoint(Trigger.new[0].ReplayId); try { // Your processing logic here } catch (Exception e) { // Handle exceptions LoggingService.logError('Order_Event__e', e); } }
2. Use Retryable Exceptions
Another powerful technique is to useEventBus.RetryableException to retry the trigger with the entire batch of events. This gives you another chance to process event messages when a transient error occurs. When you throw this exception, events are resent after a small delay (which increases in subsequent retries) in their original order based on the ReplayId field values.
apextrigger OrderEventTrigger on Order_Event__e (after insert) { try { // Check for a condition that requires retry if(!SystemStatus.isReady()) { throw new EventBus.RetryableException('System not ready, retry later'); } // Processing logic } catch (Exception e) { // Log error LoggingService.logError('Order_Event__e', e); // Determine if retryable if(isRetryableError(e)) { throw new EventBus.RetryableException('Retrying due to: ' + e.getMessage()); } } }
3. Implement Error Logging
Create a custom Exception object to log the details of errors that occur during platform event processing. This approach allows administrators to monitor and troubleshoot issues.apex// Example exception logging catch(Exception e) { // Get exception details String exDetails = e.getCause() + '; ' + e.getLineNumber() + '; ' + e.getMessage() + '; ' + e.getStackTraceString() + '; ' + e.getTypeName(); // Publish exception to a custom exception event ExceptionUtil.publishException('PlatformEventProcessor', 'Event Processing', recordId, exDetails); }
Conclusion
Platform event error handling requires a different approach than traditional Salesforce development due to its asynchronous, distributed nature. By implementing checkpoint resumption, retryable exceptions, and robust error logging, you can create resilient platform event processes that gracefully handle failures.
Remember that the event-driven architecture of platform events brings powerful decoupling capabilities, but requires thoughtful error handling strategies to ensure message delivery and processing reliability.