Which of the following statements is true about the call order of actions?

The statement about the call order of actions being true is that actions can be called before requests and after responses. This highlights the flexibility of the OutSystems platform in managing the sequence of actions during the execution of web applications.

In the context of web applications, there are points in the request-response lifecycle where actions can be triggered, such as before an HTTP request is sent to the server or after a response is received. This allows developers to implement logic to prepare data, validate inputs, handle errors, or modify the response. By providing this capability, it enhances the control developers have over the application flow, allowing for dynamic interactions depending on user input or external conditions.

The other choices introduce limitations or misconceptions about how actions can be utilized in the OutSystems environment. For instance, stating that actions are only called on error would suggest they have no application in normal operation, which is not accurate. Similarly, claiming that actions are not called for external services ignores the interaction possibilities with APIs and other integrations. Lastly, the assertion that actions can only be executed manually overlooks automated or event-driven execution patterns available in the OutSystems framework.