Are PHP Sessions Associated with Particular Files

Question

Is PHP session data associated with a particular web page or PHP file? In other words, if a session is created in foo.php, would it's session data be accessible from bar.php, assuming that neither reference the other and both are accessed directly from the web browser.

If it is file specific, how does this work with include()s? For example, if foo.php creates a session, then includes bar.php, can the code in bar.php access session data? How about if the session is created in bar.php? Would the data then be specific to bar.php or foo.php?

Answer 1

Yes, session data is available across different files and requests, that is the whole point of sessions: to provide state where the HTTP protocol doesn't. You could look upon the session as a small storage on the web server for your code to store limited data in.

If your foo.php starts a session and then includes bar.php, the code in bar.php will indeed be able to access the session. If your bar.php executes the session_start() then the foo.php can access the session from then on (so after the include()).

Please do remember: a session is unique to a specific browser and volatile. I.e: close the browser and the session will become inactive, inaccessible and expire (usually after 30 minutes).

Note:- modern browsers have the ability to reconnect with session.

Answer 2

Session data is available across all pages in php. Generally we start session(session_start()) in file(config file) which is included in all files.

So if you do not have a common file or do not want to define globally then you need to start session_start() in every file.

Answer 3

I give answer to bar.php or foo.php includes each other.

• There is always a first file that was not included and call via browser or shell
• All other files are included after that (in witch order is on you)
• If you are include a file it is almost like merging some code blocks, nothing special.
• After one file called session_start the session is present in PHP
• So whatever file is now or later included has access to the session data
• But the next file that does session_start again will throw a notice, because the session is already started
• Also a file (or better the code in file) can do session_close and some other stuff to open a new session