Determining user's page viewing time by sniffing traffic

Question

When a user request for a page (page request), browser request for several other components within that page (inline requests), i.e. images, CSSs, JSs, ...

By just sniffing the traffic between client and server, is there a way to differentiate page requests and inline requests? To find the time interval between user's page requests (page viewing time)?

Answer 1

The web is inherently stateless, so it's tricky to figure out what requests mean what. If you know, for example that the application is Java EE based, you can look for JSESSION elements in the request header to figure out if this is the same user. If you further know the pattern of page requests, you can then start to figure out how long they're spending on a page.

If you have access to the traffic on the wire, you could sneakily inject some Javascript into the outgoing page and get monitor events back.