Note: The version number is bumped because new web services are added into the Mobile app service and into the mod_chat list of external functions. Create inside a course a new Chat activity Enrol two users in that course as students (student1 and student2) Log in as the students, visit the chat URL, and enter in the chat with both users: MOODLE_URL/mod/chat/view.php?id=$cmid Send messages with the users in chat Exit chat As admin, enable "Mobile services": Plugins ► Web Services ► Mobile Create a Token for the student1 Click on Site administration ► Plugins ► Web services ► Manage tokens Next, you can do a CURL REST call simulating a WS client with the student1 user token. You need to replace the wstoken, cmid (the chat instance value) and the URL of your moodle instance curl 'MOODLE_URL/webservice/rest/server.php?moodlewsrestformat=json' --data 'cmid=$cmid&wsfunction=mod_chat_view_sessions&wstoken=$wstoken' --compressed Put a wrong number in cmid to return an exception Change the capability mod/chat:readlog to false, retest the user access to the webservice function, should return a warning Access your course logs, filter by Web service, and check if have a session view register for student1 from Webservice that you created