Force.com Apex Code Developer's Guide

Getting Started
Writing Apex
Ways to Invoke Apex
Invoking Apex
Apex Transactions and Governor Limits
Using Salesforce Features with Apex
Integration and Apex Utilities
Invoking Callouts Using Apex
Adding Remote Site Settings
SOAP Services: Defining a Class from a WSDL Document
Invoking HTTP Callouts
Using Certificates
Callout Limits and Limitations
Make Long-Running Callouts from a Visualforce Page
JSON Support
XML Support
Securing Your Data
Encoding Your Data
Using Patterns and Matchers
Finishing Touches
Reference
Appendices
Glossary
PDF

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Invoking Callouts Using Apex

An Apex callout enables you to tightly integrate your Apex with an external service by making a call to an external Web service or sending a HTTP request from Apex code and then receiving the response. Apex provides integration with Web services that utilize SOAP and WSDL, or HTTP services (RESTful services).
  • Before any Apex callout can call an external site, that site must be registered in the Remote Site Settings page, or the callout fails. Salesforce prevents calls to unauthorized network addresses.
  • If you use setEndpoint(endpoint) to specify a named credential as the endpoint, you don’t need to configure remote site settings. A named credential specifies the URL of a callout endpoint and its required authentication parameters in one definition. To set up named credentials, see “Define a Named Credential” in the Salesforce Help.

Note

To learn more about the types of callouts, see:

Callouts enable Apex to invoke external web or HTTP services. Apex Web services allow an external application to invoke Apex methods through Web services.

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