In-depth study of PHP Session cross-domain technology

In-depth study of PHP Session cross-domain technology requires specific code examples

Abstract: With the development of the Internet, cross-domain technology is becoming more and more important. This article will delve into the PHP Session cross-domain technology and provide specific code examples to help readers better understand and apply it.

Introduction
In Internet applications, cross-domain technology is very necessary. When the front end of a website needs to access data from another website, cross-domain access will be denied due to browser security policy restrictions. PHP Session cross-domain technology can help us solve this problem and make cross-domain access possible.

1. Basic knowledge of PHP Session
   Before introducing cross-domain technology, you first need to understand the basic knowledge of PHP Session. Session is a technology used to save user information. It can save user-related data between the browser and the server. Session in PHP identifies each user through a unique Session ID and stores the data on the server side. Users can access and modify their own Session data through this Session ID.
2. Cross-domain access problem
   By default, the browser does not allow access to data from one domain name to another domain name. This is the problem of cross-domain access. For example, if the front end of a website needs to access the data of another website, such access request will be denied due to the browser's security policy. At this time, we can use PHP Session cross-domain technology to solve this problem.
3. PHP Session cross-domain technology implementation
   In order to implement PHP Session cross-domain technology, we need to perform the following steps:

3.1 Create Session# on the backend of the first website ##In the back-end code of the first website, first create a Session and write relevant data to the Session. The specific code is as follows:

session_start();
$_SESSION['username'] = 'user1';
$_SESSION['email'] = 'user1@ example.com';
?>
3.2 Get Session ID

After creating the Session on the backend of the first website, we need to get the Session ID. The specific code is as follows:

session_start();
$sessionId = session_id();
echo $sessionId;
?>
3.3 Cross-domain transfer of Session ID

Pass the Session ID obtained from the first website to the second website, which can be passed through URL parameters, cookies, HTTP Header and other methods. In the following example, we will use URL parameters to pass the Session ID. The specific code is as follows:

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