What callback action is used to customize a request sent to an external REST service?

The use of the "On Before Request" callback action is crucial for customizing a request sent to an external REST service. This callback allows developers to intervene in the request lifecycle just before it is sent.

In practice, it provides a place where you can manipulate the request parameters, headers, or even the request body according to the requirements of the external service. For instance, if the external service requires specific authentication headers or custom query parameters, you can add those modifications in this callback.

This capability is essential for ensuring that the interaction with the external service aligns with its expectations and specifications, which can vary widely between different APIs. Integrating such customization increases the flexibility and robustness of your web applications when interacting with other services.

Other callback actions, while useful in their own contexts, do not serve this specific purpose. "On Consume" is generally related to handling the consumption of data from the service. The "On After Response" callback would typically be used for processing the response received from an external service rather than modifying the request being sent. "On REST Request" does not exist as a standard callback action in OutSystems for customizing requests. Thus, the "On Before Request" callback is the correct choice for customizing request details before they are dispatched