Callouts and Apex Web Services

Apex ProgrammingCallouts and Apex Web ServicesCall external REST and SOAP services safely with Named Credentials, handle JSON like a pro, respect callout limits and transaction rules, and expose your own Apex REST and SOAP APIs.Intermediate · about 75 minutesWhat you will learn

Make HTTP callouts with Http, HttpRequest and HttpResponse and handle errors and timeouts

Configure Named Credentials and External Credentials (principals, permission set mapping, custom headers) and use the callout: syntax

Serialize and deserialize JSON with typed classes, untyped maps and JSONParser

Explain the 'uncommitted work pending' rule and choose an async pattern to avoid it

Use Continuation for long-running callouts from LWC and know when External Services is the better tool

Expose versioned Apex REST endpoints with proper status codes and error bodies

Build a resilient integration with retries and logging

Contents

How a callout works

Named Credentials and External Credentials

Working with JSON

Callouts and the transaction: "uncommitted work pending"

Continuations: long-running callouts from LWC

External Services: the low-code alternative

Exposing Apex REST APIs

Apex SOAP web services

Security for integrations

Testing callouts

Worked example: a resilient shipping integration

Best practices

Common pitfalls

Hands-on exercises

Key takeaways