Explanation
A developer needs to make a call to a long running web service which is critical to finalizing their checkout process. The developer should consider the following items in their implementation:
* A new CORS entry may need to be created in Setup. CORS stands for Cross-Origin Resource Sharing, which is a mechanism that allows web browsers to make requests to servers on different domains. If the web service is hosted on a different domain than the B2B Commerce site, the developer may need to add a CORS entry in Setup to allow the browser to access the web service. This entry specifies the origin, path, and method of the request, as well as any headers or cookies that are allowed1.
* A new Named Credential may need to be created in Setup. A Named Credential is a type of metadata that stores the URL and authentication settings of a web service. By using a Named Credential, the developer can avoid hardcoding the web service URL and credentials in their code, and instead reference the Named Credential by name. This makes the code more secure and easier to maintain2.
* An Apex method returning a Continuation will need to be created. A Continuation is a special type of Apex object that allows the developer to make asynchronous calls to long running web services.
Byusing a Continuation, the developer can avoid blocking the main thread and improve the user experience. A Continuation method must return a Continuation object, specify the web service URL and parameters, and register a callback method that handles the response3.
Option D and Option E are incorrect because they are not relevant to the scenario. Option D suggests that the developer should broker the requests to the web service, which means to use an intermediary service that manages the requests and responses. This may be useful for some scenarios, but it is not required for making a call to a long running web service. Option E suggests that the developer should create a new Remote Site in Setup, which is a way to whitelist the domains that can be accessed from Apex code. However, this is not necessary if the developer uses a Named Credential, which automatically handles the Remote Site setting2.
References:
* Set Up CORS
* Named Credentials
* Continuation Class