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PHP core components and operating principles
php includes a total of 3 Modules:
1, php kernel
2, zend engine
3, php extension layer
Kernel: Used to handle requests, file streams, error handling and other related processing.
zend engine: Convert the source file into machine language (actually bytecode opCode), and then run it on the zend virtual machine (this is similar to the java virtual machine).
Extension layer: A set of functions, class libraries and streams that PHP uses to perform some specific operations, such as the need to use mysql extensions.
zend module includes:
1. zend engine, this is the lowest level .
2. zend api
3. zend extensions, extensions of zend engine. For example, the most famous one is: php_xdebug_version..._vc6.dll
Pay attention to understanding the difference between configuration and entity files
All configuration files, whether windows or linux , unix system, are just a description of the function of the software/program/system, a kind of scheduling, a kind of adjustment (illustrative/descriptive/command/) document! It is equivalent to cooking/cooking Make a list (for example, how many grams of dish A, how many grams of dish B, how much oil, how much salt), and then when you cook/cook, just follow this list ("Stir-fry configuration").
When the program starts, it will follow the instructions in your "configuration file" to start certain functions/features and specifications you specified. So the configuration file is actually a kind of document, which may be an ini , conf, cnf, xml, etc. (httpd.conf, php.ini, my.cnf).
The functions of actual software/programs/systems still have to be realized by specific physical files/physical objects/components, etc. For example: when you cook, you need those specific vegetables, oil, salt, etc. Etc. For programs, you must have the corresponding dll file, or so file, etc. Otherwise, if you only have the configuration file, it is equivalent to talking on paper. Is it empty talk? Since you want to configure it, you need that software/program, etc. There is configurability: it must be configurable and can be set!
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