Calling SOAP Services from Apex
Force.com provides a code generation tool in its native user interface for creating Apex-friendly classes and methods from SOAP Web service definitions found in WSDL files. Like most code generation tools, using it is a hit-or-miss experience. When it works on your WSDL, it can save considerable effort over the alternative of manually constructing and parsing SOAP messages. But be prepared for cryptic error messages when code cannot be generated due to the impedance mismatch between WSDL, SOAP, and Apex.
If you’re able to use your WSDL wholesale or slim it down to successfully generate Apex code, most of your work is done. Invoking the remote SOAP Web service becomes a relatively simple matter of preparing the right input via Apex classes, invoking a method, and using the resulting Apex classes in your program. No interaction with HTTP or XML is necessary because these details are hidden by the generated Apex code.
Caution
For integrations that require a series of Web service calls strung together with cookies to maintain state between them, you cannot use the Apex code generated from WSDL. Additionally, generated code does not support HTTP-level authentication.
In general, no developer-modifiable options exist in the generated code, which uses an internal, undocumented API to perform the actual Web service callout. If your Web service call requires control over the SOAP message content or HTTP headers, you must write code to make the request from scratch using HTTPRequest, as described in the next subsection.
Here are the steps needed to generate Apex from WSDL:
1. Save the WSDL file on your local machine.
2. Go to the App Setup area and click Develop, Apex Classes.
3. Click the Generate from WSDL button.
4. Click the Browse button and locate the WSDL in your file system and then click the Parse WSDL button. The WSDL must describe a document-style service because Remote Procedure Call (RPC) is not supported.
5. Each WSDL namespace can be mapped to an Apex class name to be generated. You can map multiple namespaces to the same class. Force.com suggests an Apex class name based on the WSDL, but you can override this suggestion. When you’re done naming the classes, click the Generate Apex Code button.
6. If you refresh your Force.com IDE by right-clicking the project and selecting Force.com, Refresh from Server, you should see the new Apex class. If not, make sure that it was generated successfully and that you’ve subscribed to new Apex classes by right-clicking the Force.com project and selecting Force.com, Add/Remove Metadata Components.
Caution
Due to the complexity of WSDL, conflicts between its naming conventions and Apex syntax rules, and the limit on Apex class size, the WSDL to Apex feature might not work as expected in all cases. Investigate these issues further in the Force.com online help. As a best practice, keep your WSDL as simple as possible. Manually edit it to strip out extraneous services and ports.
Before you can run this code, you must authorize Force.com to make an outbound call to the endpoint of the Web service. Go to the Administration Setup area, click Security Controls, Remote Site Settings, and then add the host.