First I'd like to know if PHP 8.0 is supported
UBB.threads 7.7.5 fully supports PHP 7. UBB.threads 8.0.0 is still being tested with PHP 8 and has multiple changes made to the core scripts to support PHP 8. Its still being worked on with new features and applying further corrections to some PHP 8 issues that might not blatantly be apparent on simple tests. A few of the third party assets are also being replaced or updated to fully support PHP 8. UBB.threads 8.0.0 will be released shortly.
Second I'm wondering how IIS knows which PHP engine to call for a particular request. IIS allows the installation of multiple versions of PHP, and I was wondering how IIS knows which to use at any given time.
Does the PHP script itself contain some type of identifier that identifies its preferred PHP?.
Both Apache and IIS use the PHP executable that you have associated with the *.php file extension.
In Microsoft IIS 10, you would use the PHP Manager
inside of your IIS Manager, which looks like this:
This is also the same with Linux using the command executable you have associated with an file extension. For example, your .htaccess file may specify the following line to choose between which executable will be used -- but only if your host has setup a multi-PHP environment. Current CPanel users are already familiar with MultiPHP Manager
controlling these .htaccess lines
# AddHandler application/x-httpd-ea-php56 .php .php7 .phtml
# AddHandler application/x-httpd-ea-php70 .php .php7 .phtml
# AddHandler application/x-httpd-ea-php72 .php .php7 .phtml
# AddHandler application/x-httpd-ea-php73 .php .php7 .phtml
# AddHandler application/x-httpd-ea-php74 .php .php7 .phtml
AddHandler application/x-httpd-ea-php80 .php .php8 .phtml