Overview: This details how a user_id is set by the Adaptive Plugin using a cookie and shows how this behavior can be modified.
User ID via Cookie
The default behavior for the IRIS.TV Adaptive Library is to drop a domain-specific cookie for a user. For users located in Europe, the default behavior is to not set a cookie. Every time the plugin is initialized, it will check if an IRIS.TV cookie already exists for that domain and use the user_id on the cookie. If one is not found, it will create a new one. The cookie will expire after 30 days of inactivity.
This behavior can be changed through the "set_cookie" Plugin Customization Option (details on those options here: Adaptive Plugin Customization Options). Setting "set_cookie" to false prevents the Adaptive Library from creating a cookie for a user when the plugin is initialized.
An example of an IRIS.TV Adaptive Library configuration with "set_cookie":