I have an existing website that I want to turn into an OpenID provider. All my user accounts are stored in a mysql table.
I figured since an OpenID is represented as a URL, I am going to do something like: http://login.mydomain.com/username
I've setup a subdomain, and created an htaccess that redirects all URLs to /login.php?username=[username]
The way I see it, and tell me if I'm wrong, someone goes to let's say StackOverflow, they enter http://login.mydomain.com/myUsername. They get to a page on my server that asks for their password (since I already know their username), I check that it matches, and return the key?
People online recommended using Zend_OpenId_Provider. I've been reading their documentation (http://framework.zend.com/manual/en/zend.openid.provider.html), but I find it very confusing. They have no real world example where the user login/password are stored in a database.
I've also seen php-open-id (http://github.com/openid/php-openid), but no help there either.
It seems to be a pretty common thing to do. Is there a tutorial out there or an example I can easily adapt?