Continuation Multiple Asynchronous Callouts

To make multiple callouts to a long-running service simultaneously from a Visualforce page, you can add up to three requests to the Continuation instance. An example of when to make simultaneous callouts is when you’re making independent requests to a service, such as getting inventory statistics for two products.When you’re making multiple callouts in the same continuation, the callout requests run in parallel and suspend the Visualforce request. Only after all callout responses are returned does the Visualforce process resume.The following Visualforce and Apex examples show how to make two asynchronous callouts simultaneously by using a single continuation.