Django (web framework)

Django (pronounced /ˈdʒæŋɡoʊ/ JANG-goh[1]) is an open source web application framework, written in Python, which follows the model-view-controller architectural pattern.[2] It was originally developed to manage several news-oriented sites for The World Company[3] of Lawrence, Kansas, and was released publicly under a BSD license in July 2005; the framework was named after gypsy jazz guitarist Django Reinhardt.[4] In June 2008 it was announced that a newly formed Django Software Foundation will take care of Django in the future. [5]

Django's primary goal is to ease the creation of complex, database-driven websites. Django emphasizes reusability and "pluggability" of components, rapid development, and the principle of DRY (Don't Repeat Yourself). Python is used throughout, even for settings, files, and data models.

Django also provides an optional administrative CRUD (create, read, update and delete) interface that is generated dynamically through introspection and configured via admin models.




Components
Screenshot of the Django admin interface for modifying a user.

The core Django framework consists of an object-relational mapper which mediates between data models (defined as Python classes) and a relational database; a regular-expression-based URL dispatcher; a view system for processing requests; and a templating system.

Also included in the core framework are:

* A lightweight, standalone web server for development and testing.
* A form serialization and validation system which can translate between HTML forms and values suitable for storage in the database.
* A caching framework which can use any of several cache methods.
* Support for middleware classes which can intervene at various stages of request processing and carry out custom functions.
* An internal dispatcher system which allows components of an application to communicate events to each other via pre-defined signals.
* An internationalization system, including translations of Django's own components into a variety of languages.
* A serialization system which can produce and read XML and/or JSON representations of Django model instances.
* A system for extending the capabilities of the template engine.
* An interface to Python's built-in unit test framework.

[edit] Bundled applications

The main Django distribution also bundles a number of applications in its "contrib" package, including:

* An extensible authentication system.
* The dynamic administrative interface.
* Tools for generating RSS and Atom syndication feeds.
* A flexible commenting system.
* A sites framework that allows one Django installation to run multiple websites, each with their own content and applications
* Tools for generating Google Sitemaps.
* Tools for preventing cross-site request forgery.
* Template libraries which enable the use of lightweight markup languages such as Textile and Markdown.
* A framework for creating GIS applications.

[edit] Applications built on Django

* The Pinax framework provides reusable applications aimed at Django-based social networking websites.
* RapidSMS is a framework for SMS applications built on Django.
* Pootle is an online translation management tool.
* Review Board is a web-based code review tool.

[edit] Server arrangements

Django can be run in conjunction with Apache using mod_python or mod_wsgi. Django also includes the ability to launch a FastCGI server, enabling use behind any web server which supports FastCGI. It should also be possible to use other WSGI-compliant web servers. Django officially supports four database backends: PostgreSQL, MySQL, SQLite and Oracle. MS SQL backend can be used with django-mssql but only in Microsoft operating systems, similarly external backends exist for IBM DB2 and SQL Anywhere.

Django may also be run in conjunction with Jython on any Java EE application server such as GlassFish or JBoss. In this case django-jython must be installed in order to provide JDBC drivers for database connectivity, which also provides functionality to compile Django in to a .war suitable for deployment.

Versions of Django prior to 1.0 had multithreading issues [6] and it would be recommended that those versions of Django only be used in a single threaded server configuration, such as with Apache prefork MPM using mod_python or embedded mode of mod_wsgi. Although Django 1.0 is principally believed to now be thread safe, some minor threading issues are still occasionally being found; it may be prudent to continue to use a single threaded server configuration and/or stay current with Django releases and notices about the multithreading issues. [6]

Google App Engine includes Django 0.96.1[7] as one of the bundled frameworks.
[edit] Django books

* July 2009: Apress published the second edition of the book The Definitive Guide to Django, for version 1.1, released under the GNU Free Document License (the first edition of the book was published in December 2007.)[8]
* June 2009: Apress published the second edition of the book Practical Django Projects by James Bennett (the first edition was released in June 2008.)[9]
* March 2009: Packt Publishing published Django 1.0 Website Development by Ayman Hourieh [10]
* December 2008: Packt Publishing published Django 1.0 Template Development by Scott Newman [11]
* December 2008: Apress also published the book Pro Django by Marty Alchin.[12]
* November 2008: Addison-Wesley published Python Web Development with Django by Jeff Forcier, Wesley Chun, and Paul Bissex. [13]
* April 2008: Packt Publishing published Learning Website Development with Django by Ayman Hourieh [14]