A practical architect’s comparison of Salesforce Outbound Messages and Platform Events — when to use each, security and scalability considerations, and best practices for building resilient integrations.
Overview
Salesforce offers multiple asynchronous integration mechanisms. Two common choices are Outbound Messages (SOAP-based) and Platform Events (event-driven). This post explains their architectures, pros and cons, and provides a decision framework to help architects, admins, and developers choose the right approach.
Outbound Messages — Quick Summary
Outbound Messages are a declarative, SOAP-based way to push record data from Salesforce to a single external endpoint. They are reliable, require minimal setup, and include built-in retry logic, making them suitable for legacy SOAP integrations and simple point-to-point use cases.
Platform Events — Quick Summary
Platform Events are Salesforce’s native event-driven mechanism built for publish/subscribe architectures. Events are published to the Event Bus and can be consumed by multiple subscribers (internal or external) via Streaming API/CometD, EMP Connector, or REST publish endpoints. They are designed for scalability and loose coupling.
Key Comparison
- Protocol: Outbound Message uses SOAP/XML; Platform Events use a JSON-based publish/subscribe model (CometD/Streaming API).
- Delivery: Outbound Messages provide point-to-point guaranteed delivery with 24-hour retries; Platform Events provide at-least-once delivery with replay IDs retained for 72 hours.
- Consumers: Outbound Messages have a single consumer; Platform Events support multiple subscribers.
- Scalability: Outbound Messages are limited; Platform Events scale well (including High-Volume Platform Events).
When to Use Each
- Use Outbound Message when: You need a low-effort, declarative SOAP integration with guaranteed delivery for a single legacy endpoint or strict XML schema requirements.
- Use Platform Events when: You need a loosely coupled, scalable publish/subscribe system where multiple services react to the same business event in real time.
Best Practices for Architects
- Design for loose coupling — prefer Platform Events for multi-consumer and evolving ecosystems.
- Implement idempotent endpoints and include unique identifiers to avoid duplicate processing.
- Enforce TLS/HTTPS, use OAuth/Connected Apps for Platform Events, and consider middleware or API gateways to reduce surface area.
- Use High-Volume Platform Events (HVPE) for large-scale workloads and Publish After Commit to ensure events fire only after successful transactions.
- Monitor both approaches: use Delivery Status reports for Outbound Messages and Event Bus metrics & replay monitoring for Platform Events.
Decision Framework
Architects should standardize choices with a simple matrix covering complexity, consumer count, volume, protocol, governance overhead, and scalability. This reduces ad-hoc decisions and ensures alignment with long-term integration strategy.
Conclusion
Neither Outbound Messages nor Platform Events is universally “better.” The right choice depends on your integration goals: legacy SOAP-driven, point-to-point integrations favor Outbound Messages; modern event-driven, multi-consumer architectures favor Platform Events. Prioritize security, observability, and idempotency regardless of your choice.
Why this matters: Salesforce admins, developers, and architects must choose patterns that match both immediate business needs and long-term scalability. The correct integration pattern reduces technical debt and supports future growth.