Kohana was originally created as a project fork of the CodeIgniter PHP framework under the name Blue Flame. The principal reason for the fork was to create a more community-based web application framework as many users were frustrated with CodeIgniter's lack of bug fixes and inclusion of new features requested by the community. In July 2007, Blue Flame was renamed to Kohana to avoid possible copyright issues. The name Kohana was chosen when the developers began looking through Native American dictionaries to find words that would have little copyright conflict. Kohana is the Sioux word for 'swift.' It is also the Japanese word for 'tiny flower', Ukrainian word for 'beloved' (only of feminine gender) and the name of a famous killer whale (Kohana)--none of which have any relation to the original intended meaning.
While the initial release of Kohana was essentially an improved version of CodeIgniter, by the end of 2007 the Kohana development team had released version 2.0 which was a complete re-write from the ground up. The new version 2.0 was strictly a PHP5 framework and has formed the basis for all other releases since.
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Cascading resources visualized.
Strict PHP5OOP. Offers many benefits: visibility protection, automatic class loading, overloading, interfaces, abstracts, and singletons.
Kohana has joined the GoPHP5 initiative. All releases from 2.2 on will conform with this project.
Continues CodeIgniter design patterns. Anyone who has used CodeIgniter will quickly understand Kohana's structure and design patterns.
Community, not company, driven. Kohana is driven by community discussion, ideas, and code. Kohana developers are from all around the world, each with their own talents. This allows a rapid and flexible development cycle that can respond to bugs and requests within hours, instead of days or months.
GET, POST, COOKIE, and SESSION arrays all work as expected. Kohana does not limit your access to global data, but offers the same filtering and XSS protection that CodeIgniter does.
Cascading resources, modules, and inheritance. Controllers, models, libraries, helpers, and views can be loaded from any location within your system, application, or module paths. Configuration options are inherited and can by dynamically overwritten by each application.
No namespace conflicts. Class suffixes, like _Controller, are used to prevent namespace conflicts. This allows a User's controller and Users model to both be loaded at the same time.
True auto-loading of classes. This includes libraries, controllers, models, and helpers. This is not pre-loading, but true dynamic loading of classes, as they are instantiated.
Helpers are static classes, not functions. For example, instead of using form_open(), you would use form::open().
Library drivers and API consistency. Libraries can use different "drivers" to handle different external APIs transparently. For example, multiple session storage options are available (database, cookie, and native), but the same interface is used for all of them. This allows new drivers to be developed for existing libraries, which keeps the API consistent and transparent.
Powerful event handler. Kohana events can by dynamically added to, replaced, or even removed completely. This allows many changes to Kohana execution process, without modification to existing system code.