Editing Zend Engine

{{Short description|PHP scripting engine}}
{{Distinguish|text=[[Laminas]] formerly known as Zend Framework}}
{{primary sources|date=July 2016}}
{{Use dmy dates|date=August 2021}}
{{Infobox software
| name                   = Zend Engine
| title                  = Zend Engine
| logo                   = Zend_Engine_logo.png
| screenshot             = <!-- [[File: ]] -->
| caption                = 
| collapsible            = 
| author                 = [[Andi Gutmans]], [[Zeev Suraski]]
| developer              = [[Zend Technologies]], The PHP Development Team
| released               = 1999 <!-- {{Start date|1999|MM|DD|df=yes/no}} -->
| discontinued           = 
| latest release version = 3.4 (PHP 7.4) <br /> 4.0 (PHP 8.0)
| latest release date    = <!-- {{Start date and age|YYYY|MM|DD|df=yes/no}} -->
| latest preview version = 
| latest preview date    = {{Start date and age|2015|11|12|df=yes}}
| programming language   = [[C (programming language)|C]]
| operating system       = 
| platform               = 
| size                   = 
| language               = 
| genre                  = Scripting engine
| license                = [[Zend Engine License]] (some parts are under the [[PHP License]])
| repo                   = {{URL|https://github.com/php/php-src}}<ref>{{Cite web|title=php.internals: Changes to Git commit workflow|url=https://news-web.php.net/php.internals/113838|access-date=2021-04-22|website=news-web.php.net}}</ref>
| website                = {{URL|https://www.zend.com/}}
}}

The '''Zend Engine''' is a [[compiler]] and [[runtime system |runtime environment]] for the [[PHP]] scripting language and consists of the Zend Virtual Machine, which is composed of the Zend Compiler and the Zend Executor, that compiles and executes the PHP code.<ref>{{cite web |url=http://www.phpinternalsbook.com/php7/zend_engine.html |title=Zend engine |website=PHP Internals Book |access-date=2021-10-04 }}</ref> It was originally developed by [[Andi Gutmans]] and [[Zeev Suraski]] while they were students at the [[Technion – Israel Institute of Technology]].  They later founded a company called [[Zend Technologies]] in [[Ramat Gan]], [[Israel]]. The name Zend is a combination of their forenames, Zeev and Andi.

The first version of the Zend Engine appeared in 1999 in PHP version 4.<ref>{{cite web|url=http://www.zend.com/en/community/php/|title=Zend's History with PHP|publisher=Zend Technologies}}</ref> It was written in [[C (programming language)|C]] as a highly optimized modular back-end, which for the first time could be used in applications outside of PHP. The Zend Engine provides memory and resource management, and other standard services for the PHP language. Its performance, reliability and [[extensibility]] played a significant role in PHP's increasing popularity.

This was followed by ''Zend Engine 2'' at the heart of [[PHP 5]].

This was followed by ''Zend Engine 3'', originally codenamed ''phpng'', which was developed for [[PHP 7]] and significantly improves performance.<ref>{{Cite web|url=https://www.php.net/manual/en/faq.general.php#faq.general.relation-versions|title=PHP: General Information - Manual|website=php.net|access-date=2019-11-22}}</ref>

The newest version is ''Zend Engine 4'', which was developed for [[PHP 8]].

The source code for the Zend Engine has been freely available under the [[Zend Engine License]] (although some parts are under the [[PHP License]]) since 1999,<ref>{{Cite web|title=- License update · php/php-src@fec59d3|url=https://github.com/php/php-src/commit/fec59d3b4da7fdc111dd0af19a4b0488dc817fc7|access-date=2021-12-26|language=en|date=1999-07-14|first=Andi|last=Gutmans}}</ref> as part of the official releases from php.net, as well as the official [[git (software)|git]] repository or the [[GitHub]] mirror. Various volunteers contribute to the PHP/Zend Engine codebase.

== Architecture ==
Zend Engine is used internally by PHP as a compiler and runtime engine. 
PHP Scripts are loaded into memory and compiled into Zend [[opcodes]]. 
These opcodes are executed and the HTML generated is sent to the client.<ref>{{cite web|url=http://www.careerride.com/PHP-zend-engine.aspx|title=PHP - What is zend engine?|publisher=careerride}}</ref>

To implement a Web script interpreter requires three parts:
# The interpreter part analyzes the input code, translates it, and executes it.
# The functionality part implements the functionality of the language (its functions, etc.).
# The interface part talks to the Web server, etc.
Zend takes part 1 completely and a bit of part 2; PHP takes parts 2 and 3.

Zend itself really forms only the language core, implementing PHP at its very basics with some predefined functions.

==See also==
*{{Portal inline|Free and open-source software}}

==References==
{{reflist}}

==External links==
* {{Official website}}
* {{cite web|url= http://www.zend.com/engine2/ZendEngine-2.0.pdf |title= Zend Engine 2.0 Design |archive-date= 13 August 2011 |archive-url= https://web.archive.org/web/20110813194014/http://www.zend.com/engine2/ZendEngine-2.0.pdf}}
* [https://github.com/php/php-src Official git repository]
* {{cite web|url= https://wiki.php.net/internals/engine |title= Zend Engine Documentation |date= 22 September 2017  |website= PHP development wiki }}

{{PHP}}

[[Category:1999 software]]
[[Category:C (programming language) software]]
[[Category:PHP]]
[[Category:PHP software]]