Integration Basics: Sync vs Async
By the end of this lesson, you'll be able to:
- Explain what an integration is in the Salesforce context
- Distinguish a synchronous callout from an asynchronous one
- Recognize the governor limit that makes this distinction matter
Prerequisites: Module 35: "Project: Client Health Dashboard"
What "integration" means here
Every lesson so far has worked entirely within Salesforce's own data. An integration connects Apex to something outside it — a shipping-rate API, a payment processor, an external inventory system. Module 31's "Mocking HTTP Callouts" lesson tested this exact boundary already; this module teaches the calling side that lesson assumed existed.
Synchronous: wait for the answer
HttpResponse response = new Http().send(request); // execution pauses here until a response arrives
System.debug(response.getBody());A synchronous callout pauses the current transaction until the external system responds — simple to reason about, but the whole transaction is now only as fast as the slowest external system it's waiting on.
Why synchronous callouts have real limits
Apex allows a maximum of 10 seconds of total callout time per transaction, and — critically — a callout can only run in specific contexts: never inside a trigger directly, since a trigger might be part of a larger bulk operation the callout's delay would badly affect. This is exactly why a later Asynchronous Apex module exists: moving a callout to run asynchronously (via a Queueable, covered there) sidesteps both of these constraints.
Exercise
As a comment, explain why a synchronous HTTP callout cannot be made directly inside a trigger.
Show hint
Think about what a trigger could be part of — a single record save, or a bulk operation.
Integration Basics: Sync vs Async Quiz
My Notes
Log in to keep private notes on this lesson.
Questions about this lesson
No questions yet — be the first to ask.
Log in to ask a question about this lesson.
Summary
An integration connects Apex to a system outside Salesforce — synchronously, waiting for an immediate response, or asynchronously, firing work off and moving on.