When managing multiple websites on a Windows server using Internet Information Services (IIS), a common question arises: How does IIS know which website is using which version of PHP? This inquiry is crucial for web developers and system administrators who want to ensure compatibility between their web applications and the PHP versions they rely on. In this article, we'll explore the answer to this question, examining the configuration and functionality of IIS regarding PHP versions.
Original Problem Scenario
The original inquiry can be summarized as follows: "How does IIS determine which PHP version is associated with each website it hosts?"
IIS and PHP: An Overview
IIS is a web server developed by Microsoft that allows the hosting of websites and applications. PHP (Hypertext Preprocessor) is a widely-used open-source server-side scripting language designed for web development. When running multiple websites on IIS, it's crucial to specify the PHP version each site should use, especially if the websites have different PHP requirements.
How IIS Handles Multiple PHP Versions
IIS uses a combination of configuration files and settings to determine the PHP version for each website. Here's how it works:
-
Handler Mappings: IIS utilizes handler mappings to define how requests to certain file types (like
.php) are processed. Each website can have its own handler mapping that specifies which PHP executable to use. This configuration is found in the IIS Manager under the "Handler Mappings" feature. -
Web.Config File: Each website hosted on IIS can have its own
web.configfile, which includes settings that override the global IIS settings. Within this file, you can specify which version of PHP to use by defining the appropriate handler mappings.For example:
<configuration> <system.webServer> <handlers> <add name="PHP_v7" path="*.php" verb="*" modules="FastCgiModule" scriptProcessor="C:\PHP\v7.4\php-cgi.exe" resourceType="Unspecified" /> </handlers> </system.webServer> </configuration> -
FastCGI Configuration: IIS can work with FastCGI, which is a protocol for interfacing interactive programs with a web server. Each PHP version that you install on the server can be configured to run as a FastCGI process. By associating specific versions with particular websites in their respective configuration files, IIS can effectively manage multiple PHP installations.
-
Global vs. Site-Specific Settings: When configuring PHP versions, it's important to note that settings can be applied globally (to all sites) or site-specifically. Global settings can be overridden by site-specific settings in the
web.configfile.
Practical Example
Imagine you are running two websites on your IIS server:
- Site A requires PHP 7.3.
- Site B requires PHP 8.0.
You would set up the handler mappings and web.config files for each website as follows:
Site A's Web.Config:
<configuration>
<system.webServer>
<handlers>
<add name="PHP_v7.3" path="*.php" verb="*" modules="FastCgiModule" scriptProcessor="C:\PHP\v7.3\php-cgi.exe" resourceType="Unspecified" />
</handlers>
</system.webServer>
</configuration>
Site B's Web.Config:
<configuration>
<system.webServer>
<handlers>
<add name="PHP_v8.0" path="*.php" verb="*" modules="FastCgiModule" scriptProcessor="C:\PHP\v8.0\php-cgi.exe" resourceType="Unspecified" />
</handlers>
</system.webServer>
</configuration>
By using the above configurations, IIS will correctly serve each site using its specified version of PHP.
Conclusion
Understanding how IIS determines which PHP version to use for different websites is essential for effective web application management. By leveraging handler mappings, web.config files, and FastCGI configurations, IIS can efficiently serve multiple PHP versions across different websites. This flexibility allows developers to maintain compatibility with various applications without compromising performance or functionality.
Additional Resources
By following the guidelines laid out in this article, you'll ensure that your IIS server effectively manages different PHP versions, allowing your websites to run seamlessly.
