Using php sessions with ajax (mobile device)

I will explain my problem. I need to know if the steps below are correct:

The user enters their login details and these get submitted to the php server. If these are correct, I want to use the php code to start a session. However, because this is a mobile device I will be using html5 session storage. Now, my mobile website is all ajax based with no page reloads. So if the user submits the correct login credentials, I make an ajax response back to the user with what information? The SID/session_id of the session_start? Then, on the mobile device I place this session_id into the html5 session storage?

So, if these steps are correct, when the user then navigates around the website they are now logged in. And if they want to do something e.g. access a private page this creates an ajax request to the php server... this is where I am stuck. I assume that in this ajax request I send the session_id from the html5 session storage object, how does the php server use this id to prove the user is authentic? Presumably I need some kind of if statement and if it's not satisfied, send an 开发者_开发百科ajax response back which my javascript will interpret as redirecting the user back to the login screen.

Many thanks if anyone can help me, it will be much appreciated as I am very stuck.

Note that cookies are not an option...

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You could theoretically use HTML5 local storage to store the session ID, or transmit the session ID as a GET parameter in every request and pass it manually to PHP using session_id(), but I can't see the benefit. You might as well rely on cookies for this - they will be transmitted in Ajax requests.