Cookies

Besides the cookies used by google analytics, which are obfuscated by javascript, happs-tutorial uses cookies to track session state -- the data that corresponds to the current user's session in

data AppState = AppState {
appsessions :: Sessions SessionData,
appdatastore :: Users
} deriving (Show,Read,Typeable,Data)

When you log in, a cookie is created that expires in an hour (3600 seconds). Every time a happstack handler needs to check if a user is logged in (for example, when it needs to decide whether to show the logged-in-user menubar), a check is made to see if a cookie has been set.

The cookie code is in ControllerMisc.hs:

startsess' getLandingpage (RenderGlobals origRq ts _) user = do
let sd = SessionData user
key <- update \$ NewSession sd
addCookie (3600) (mkCookie "sid" (show key))
.....

getMbSessKey rq = runReaderT (readCookieValue "sid") (rqInputs rq,rqCookies rq)

As you can see, the basic use of cookies is surprisingly simple with the two functions addCookie and mkCookie

We've spent a good bit of time now on how happstack-server handles requests, so we're ready to move on to the major feature of happstack-state, MACID.