Cookies for Experiments
Content Experiments rely on cookies to store session data about the Content Variant a visitor is viewing and make sure they always see the same one. By default, Experience Optimization tries to write httpOnly cookies. But if you are using REL, or if it cannot write the cookies in the header (for example, when the response buffer is flushed), Experience Optimization cannot directly read and write cookies. In such circumstances, a JavaScript cookie is written.
- Changing the buffer size
-
When the response buffer is flushed (that is, it is kept low for performance reasons), the header is sent in the response before Experience Optimization can write the
httpOnlycookie. In this case, the tags or controls will output JavaScript to set a cookie to avoid invalidating the Experiment. - Writing out cookies for REL–based implementation
-
If your Output Format is
REL(Render Engine Language), the Content Delivery Web service renders content at request time. SinceRELhas no Web context, Experience Optimization cannot directly read and write cookies.