Apex Developer Guide

Apex Developer Guide
Getting Started with Apex
Writing Apex
Running 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
Named Credentials as Callout Endpoints
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
Process for Using Asynchronous Callouts
Testing Asynchronous Callouts
Asynchronous Callout Limits
Making Multiple Asynchronous Callouts
Chaining Asynchronous Callouts
Making an Asynchronous Callout from an Imported WSDL
JSON Support
XML Support
Securing Your Data
Encoding Your Data
Using Patterns and Matchers
Debugging, Testing, and Deploying Apex
Apex Language Reference
Appendices
Glossary
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Making an Asynchronous Callout from an Imported WSDL

In addition to HttpRequest-based callouts, asynchronous callouts are supported in Web service calls that are made from WSDL-generated classes. The process of making asynchronous callouts from a WSDL-generated class is similar to the process for using the HttpRequest class.

When you import a WSDL in Salesforce, Salesforce autogenerates two Apex classes for each namespace in the imported WSDL. One class is the service class for the synchronous service, and the other is a modified version for the asynchronous service. The autogenerated asynchronous class name starts with the Async prefix and has the format AsyncServiceName. ServiceName is the name of the original unmodified service class. The asynchronous class differs from the standard class in the following ways.

  • The public service methods contain an extra Continuation parameter as the first parameter.
  • The Web service operations are invoked asynchronously and their responses are obtained with the getValue method of the response element.
  • The WebServiceCallout.beginInvoke and WebServiceCallout.endInvoke are used to invoke the service and get the response respectively.

You can generate Apex classes from a WSDL in the Salesforce user interface. From Setup, enter Apex Classes in the Quick Find box, then select Apex Classes.

To make asynchronous Web service callouts, call the methods on the autogenerated asynchronous class by passing your Continuation instance to these methods. The following example is based on a hypothetical stock-quote service. This example assumes that the organization has a class, called AsyncSOAPStockQuoteService, that was autogenerated via a WSDL import. The example shows how to make an asynchronous callout to the service by using the autogenerated AsyncSOAPStockQuoteService class. First, this example creates a continuation with a 60-second timeout and sets the callback method. Next, the code example invokes the beginStockQuote method by passing it the Continuation instance. The beginStockQuote method call corresponds to an asynchronous callout execution.

When the external service returns the response of the asynchronous callout (the beginStockQuote method), this callback method is executed. It gets the response by calling the getValue method on the response object.

The following is the entire controller with the action and callback methods.

This example shows the corresponding Visualforce page that invokes the startRequest method and displays the result field.

Testing WSDL-Based Asynchronous Callouts

Testing asynchronous callouts that are based on Apex classes from a WSDL is similar to the process that’s used with callouts that are based on the HttpRequest class. Before you test ContinuationSOAPController.cls, create a class that implements WebServiceMock. This class enables safe testing for ContinuationTestForWSDL.cls, which we'll create in a moment, by enabling a mock continuation and making sure that the test has no real effect.

This example is the test class that corresponds to the ContinuationSOAPController controller. The test method in the class sets a fake response and invokes a mock continuation. The callout isn’t sent to the external service. To perform a mock callout, the test calls these methods of the Test class: setContinuationResponse(requestLabel, mockResponse) and invokeContinuationMethod(controller, request).