Authentication

Hi,

I'm wondering if we have an API for Authenticate the Moodle user by sending an HTTP request,

for example, I know the web service API for moodle that we can get the user info:

http://mysite.com/moodle/webservice/rest/server.php?wstoken=token&wsfunction=core_user_get_users_by_id&userids[0]=1&moodlewsrestformat=xml

Is there any url that we can use to verify the username and password, and return maybe a boolean to indicate the result?

Thanks a lot