A practical comparison for architects deciding between Salesforce Outbound Messages and Platform Events — when to use each, security considerations, and best practices for scalable integrations.
Understanding the choice
Salesforce offers multiple asynchronous integration options. Outbound Messages (OM) are SOAP-based, point-to-point notifications suited to legacy systems, while Platform Events (PE) power event-driven, publish/subscribe architectures for modern, scalable integrations.
Key differences
- Protocol: Outbound Message uses SOAP/XML; Platform Events use JSON over the Event Bus (CometD/Streaming API).
- Delivery model: OM is point-to-point with 24-hour retries; PE is publish/subscribe with replay IDs and 72-hour retention.
- Scalability: OM is limited; PE supports high-volume events and multiple consumers.
- Security: OM supports basic auth / mutual TLS; PE uses OAuth 2.0 via Connected Apps and TLS transport.
When to choose Outbound Message
Use Outbound Messages for simple, declarative integrations where the external system requires SOAP, or when you need a low-code solution with guaranteed retries and predictable XML schemas.
- Legacy SOAP-only endpoints (ERP, on-prem middleware)
- Low-volume, point-to-point integrations
- Regulatory contexts that favor XML/schema validation
When to choose Platform Event
Platform Events are ideal for event-driven systems requiring loose coupling, multiple subscribers, and scalability. They integrate well with modern cloud architectures, message meshes, and streaming consumers.
- Microservice architectures and multi-consumer workflows
- Real-time business events (orders, payments, case escalations)
- High-throughput systems using High-Volume Platform Events
Best practices for architects
- Design for loose coupling: choose PE for future extensibility.
- Implement idempotent endpoints or deduplication logic to handle retries and replays.
- Enforce encryption (TLS) and use middleware or API gateways for added security and observability.
- Use Publish After Commit to ensure events are only published on successful transactions.
- Monitor delivery: use OM delivery reports and Event Bus metrics for PE.
Decision checklist
- Need multiple consumers or event routing? → Platform Event
- SOAP-only legacy endpoint & declarative setup desired? → Outbound Message
- Expect growth and high throughput? → Platform Event (HVPE)
Combining both patterns is also valid — for instance, OM to middleware which then publishes PE to an event mesh.
Conclusion
Choosing between Outbound Messages and Platform Events depends on your integration strategy, system maturity, and scalability needs. Outbound Messages remain a dependable option for legacy, SOAP-based use cases, while Platform Events are the strategic choice for modern, event-driven architectures. Architects should balance immediate needs with long-term flexibility, governance, and observability when designing integrations.
Why this matters: For Salesforce admins, developers, and architects, picking the right pattern affects system resilience, future integration velocity, and operational overhead. Align your choice with the enterprise roadmap — favor Platform Events when building for scale, and use Outbound Messages when simplicity and SOAP compatibility are primary constraints.