Test Case: Session Persistence

There are 2 types of HTTP cookies:

Session cookies are used by a physical browser that accesses a website to maintain application session persistence. They are usually stored in the browser's memory until it is closed. After the browser is restarted and navigated to the same website, a new application session will be established. A website session is controlled by one (or more) HTTP session cookies, so a new session means a new value of the cookie.
Non-session cookies are used by a physical browser to persist website data for an extended period of time. They are usually stored in a file on the browser's machine until they expire.

In StresStimulus, a VU can either restart a browser on every iteration (the session cookie will change on every iteration) or leave the browser open across all iterations (the session cookie will stay the same on every iteration). Maintaining session persistence across all iterations can be useful when a test case has a login process that needs to be done only on the first iteration and not on subsequent iterations.

Here are two examples:

Internal users are signing in to the application in the morning and maintain the same session while navigating through the scenario many times throughout the day. The server renders a session cookie on the first iteration, and StresStimulus will reuse it in subsequent iterations. A login is not required in subsequent iterations.
On the contrary, external users who use the application occasionally are signing in whenever they need to navigate through a scenario. A new session cookie is assigned in every iteration. A login is most likely required in every iteration as well.

Use the Cookie correlation scope to set which cookies are correlated between iterations.

Select All to auto-correlate all cookies. This will simulate VUs that keep their browsers open and have their session persist across all iterations. The session identified by a cookie was carried over to the subsequent iteration.
Select None not correlate any cookie and use the recorded values instead. This option eliminates session persistence between iterations to emulate a user that re-opens the web browser on every iteration.
Select Session to auto-correlate only session cookies.
Select Non-session to auto-correlate only non-session cookies.

Note: Session persistence within an iteration is always maintained.