Set up Moodle web services and call its REST API

Steps

1. As a Moodle administrator, enable web services at Site Administration > Advanced Features > Enable web services, then enable the REST protocol at Site Administration > Plugins > Web Services > Manage Protocols.
2. Create a dedicated service at Site Administration > Plugins > Web Services > External Services; add the specific API functions your integration needs (e.g., core_user_get_users, core_enrol_get_enrolled_users) to that service.
3. Create or designate a Moodle user with the appropriate capabilities, then generate a token for that user at Site Administration > Plugins > Web Services > Manage Tokens, associating it with your external service.
4. Call the REST endpoint using HTTPS: GET or POST to https://yourmoodle.example.com/webservice/rest/server.php?wstoken=your_token&wsfunction=function_name&moodlewsrestformat=json plus any function-specific parameters.
5. Parse the JSON response; Moodle wraps successful responses directly in the returned object, but errors return an object with an exception key and message field — always check for the exception key before processing the result.
6. For bulk operations (e.g., enrolling many users), batch calls where the function supports array parameters rather than making one HTTP call per user to avoid hitting server timeout or rate limits.