Drupal

Drupal

Screenshot  Home page of a default Drupal 6 installation
Original author(s)	Dries Buytaert
Initial release	January 2001 (2001-01)
Stable release	6.19 / August 11, 2010; 6 months ago (2010-08-11)
Preview release	7.0-alpha 6 / July 9, 2010; 7 months ago (2010-07-09)[1]
Development status	Active
Written in	PHP
Operating system	Cross-platform
Type	Content management framework, Content management system, Community and Blog software
License	GNU General Public License version 2
Website	http://drupal.org

Drupal (pronunciation: /ˈdruːpəl/) is a free and open source content management system (CMS) written in PHP and distributed under the GNU General Public License.^[2][3][4] It is used as a back-end system for at least 1% of all websites worldwide ranging from personal blogs to larger corporate and political sites including whitehouse.gov and data.gov.uk.^[5][6] It is also used for knowledge management and business collaboration.

The standard release of Drupal, known as Drupal core, contains basic features common to most CMSs. These include user account registration and maintenance, menu management, RSS-feeds, page layout customization, and system administration. The Drupal core installation can be used as a brochureware website, a single- or multi-user blog, an Internet forum, or a community website providing for user-generated content.

Over 5800 free (as of July 20, 2010) third-party community-contributed modules, known as contrib modules, are available to alter and extend Drupal's core capabilities and add new features or customize Drupal's behavior and appearance. Because of this plug-in extensibility and modular design, Drupal is sometimes described as a content management framework.^[3][7] Drupal is also described as a web application framework, as it meets the generally accepted feature requirements for such frameworks.

Although Drupal offers a sophisticated programming interface for developers, no programming skills are required for basic website installation and administration.^[8]

Drupal runs on any computing platform that supports both a web server capable of running PHP 4.4.0+ (including Apache, IIS, Lighttpd, and nginx) and a database (such as MySQL or PostgreSQL) to store content and settings.^[4]

History

Originally written by Dries Buytaert as a message board, Drupal became an open source project in 2001.^[9] Drupal is an English rendering of the Dutch word “druppel”, which means “drop” (as in “a water droplet”).^[10] The name was taken from the now-defunct Drop.org website, whose code slowly evolved into Drupal. Buytaert wanted to call the site “dorp” (Dutch for “village”) for its community aspects, but made a typo when checking the domain name and thought it sounded better.^[9]

A large community now helps develop Drupal^[11], and Drupal's popularity is growing rapidly. From May 2007 to April 2008, Drupal was downloaded from the Drupal.org website more than 1.4 million times, an increase of approximately 125% from the previous year.^[12][13]

As of July 2010, hundreds of well-known organizations use Drupal^[14], including companies, non-profits^[15], schools, and individuals. No one knows exactly how many websites currently use Drupal, but it was estimated to be about 7.2 million as of July 2010. ^[16] Drupal has also won several Packt Open Source CMS Awards^[17] and three times (in a row) won the Webware 100.^[18][19]

Drupal 6.19, released in August 2010, is the latest release.^[20] On March 5, 2009, Dries Buytaert announced a code freeze for Drupal 7 for September 1, 2009.^[21] The latest test version, DRUPAL-7-0-ALPHA-6, was released on July 9, 2010.^[1] There is no date announced yet for the final release of Drupal 7.

Drupal core

Drupal core is the stock installation of Drupal, which can be optionally extended by third-party contributions. In its default configuration, a Drupal website's content can be contributed by either registered or anonymous users (at the discretion of the administrator) and is made accessible to web visitors by a variety of selectable criteria. Drupal core also includes a hierarchical taxonomy system, which allows content to be categorized or tagged with key words for easier access.^[8]

Drupal maintains a detailed changelog of core feature updates by version.^[22]

Core modules

Drupal core includes core modules which can be enabled by the administrator to extend the functionality of the core website.^[23]

The core Drupal distribution provides a number of features^[23], including:

Core themes

The color editor being used to adjust the "Garland" core theme

Drupal core includes selectable core themes, which customize the aesthetic "look and feel" of the site.^[25]

The Color Module, introduced in Drupal core 5.0, allows administrators to change the color scheme of certain themes via a Web-browser interface. This feature was added to allow a high level of customization for administrators.^[26]

Localization

By February 2008, Drupal's interface had been made available in 44 languages besides English (the default).^[27] Support is included for right-to-left languages such as Arabic, Persian and Hebrew.^[28]

Auto-update notification

Drupal can automatically notify the administrator when a new version of any module, theme, or the Drupal core itself becomes available. This feature can help keep a Drupal installation up-to-date with the latest features and security fixes.^[28]

Extending Drupal core

Drupal core is designed to be modular with a system of hooks and callbacks, which are accessed internally via an API.^[29] This design allows third-party contributed (often abbreviated to "contrib") modules and themes to extend or override Drupal's default behaviors without changing Drupal core's code.

Drupal's modular design, which isolates Drupal core's files from contributed module and themes, increases flexibility and security and allows Drupal administrators to cleanly upgrade to new releases of Drupal core without potentially overwriting their site's customizations.^[30] To maintain this separation, Drupal administrators are instructed to avoid altering Drupal core's software.^[31]

Contributed modules

Contributed Drupal modules offer a variety of features including image galleries, custom content types and content listings, WYSIWYG editors, private messaging, third-party integration tools^[32], and more. The Drupal website lists over 5800 free modules (as of July 20, 2010), written and contributed to by the Drupal community.^[7][33][34]

For example, some of the most powerful and commonly used contrib modules include:

• Content Construction Kit (CCK): allows site administrators to dynamically create content types by extending the database schema. A content type describes any kind of information to be stored in the website's database. These may include, but are not limited to, events, invitations, reviews, articles, and products.
• Views: facilitates the retrieval and presentation, through a database abstraction system, of content to site visitors.
• Panels: drag and drop layout manager that allows site administrators to visually design their site.

The CCK Fields API has been integrated into Drupal core in the development Drupal 7 branch.^[35]

Contributed themes

Contributed themes adapt or replace a Drupal site's default look and feel.

Drupal themes use standardized formats that may be generated by common third-party theme design engines. Many themes for Drupal are written in the PHPTemplate engine^[36] or, to a lesser extent, the XTemplate engine.^[37] Some templates use hard-coded PHP.

Although early versions of Drupal's theming system were criticized^[38] for being less design-oriented and more complicated than those for Mambo, Joomla! and Plone, the inclusion of the PHPTemplate and XTemplate engines in Drupal has addressed some of these concerns. The new Drupal 6 theming system utilizes a template engine in an attempt to further separate HTML/CSS from PHP. A Drupal development module, Devel, provides assistance to theme authors who use Drupal 6.

Community-contributed themes^[39] at the Drupal website are released under a free GPL license,and most of them are demonstrated at the Drupal Theme Garden^[40].

Contributed installation profiles

In the past, those wanting a fully-customized installation of Drupal had to download a pre-tailored version separately from the official Drupal core. Today, however, an installation profile can be used to create a fresh Drupal installation built to suit a specific purpose.

Installation profiles offer a way to "pre-customize" a new Drupal site without having to manually seek out and install third-party contrib modules or adjust configuration settings. They are collections of modules, themes, and associated configuration settings that "build" Drupal to taste. For example, an installation profile might be used to install Drupal as a "brochureware" site rather than a "news" site. Another installation profile might be used to install Drupal as an online store.

Popular installation profiles include OpenPublish ^[41], Drupal Commons^[42], Open Atrium^[43], Managing News^[44], Tattler^[45], and NodeStream^[46].

Community

Drupal has a large community of users and developers. More than 830,000 user accounts have been created on Drupal.org, and more than 2000 people have signed up for developer accounts. The Drupal conference happens twice a year, alternating between North America and Europe.^[47] DrupalCon Szeged 2008, held in August 2008, had an attendance of 500. DrupalCon Washington DC 2009 attracted over 1400 people.^[48] In September 2009, the conference was held in Paris, with 800 attendees.^[49] Over 3000 people registered for DrupalCon San Francisco in April 2010.^[50] The European DrupalCon 2010 took place in August 2010 at Bella Center in Copenhagen, Denmark.

There are a number of active Drupal forums,^[51] mailing lists^[52] and discussion groups^[53]. Drupal also maintains several IRC channels^[54] on the Freenode network.

There are over 20 national communities^[55] around drupal.org offering language-specific support.

DrupalCon Events

^[56]

Security

Since early in the project's history, Drupal has adopted a full transparent policy towards security ^[57]. A dedicated security team has a transparent and methodical process ^[58] to review any reported issue—whether in Drupal core or contrib. If in core, a trusted core contributor is tasked to implement a fix in an expedited fashion, followed by re-review by the security team. If in contrib, the module maintainer is asked to implement the fix, followed by a review. Once obtained, the security team announces the nature of the vulnerability and the availability of the fixed code in a timely manner, so that site administrators can immediately take remedial action. Though this policy tends to lead observers to think that Drupal has a high number of security issues, there is no proof that this is the case; the Drupal project's transparent approach is generally considered superior to the alternative—security through obscurity.

As security holes are discovered and remedied, the Drupal core is updated to new versions. Administrators of Drupal sites are automatically notified of these new releases via the Update Status module.^[59] Additionally, Drupal.org maintains a security announcement mailing list, a history of all security advisories,^[60] a security team home page ^[61], and an RSS feed^[62] with the most recent security advisories. In 2008, eleven security vulnerabilities were reported and fixed in the Drupal core.^[60] Security holes were also found and fixed in 64 of the 2243 user-contributed modules.^[60][63]

Criticism

In an article about the adoption of Drupal by the Whitehouse.gov site, Slate noted that Recovery.gov, which is devoted to tracking stimulus spending, originally used Drupal but soon hired a private contractor at a reported cost of $18 million to rework the site.^[64] The article goes on to list some common criticisms of Drupal.^[64]

• Usability: Some aspects of Drupal's administration interface can be confusing and intimidating, particularly for new administrators.^[65] According to the Interaction Design and Information Architecture program at the University of Baltimore, Drupal lacks an intuitive, easy administration user interface.^[66][67][68] The administration area is regarded as clunky and cryptic with Drupal version 5 and 6, but improved ease of use is planned with the upcoming version 7. According to Dries Buytaert, Drupal 7 won't be released until 90% of the problems identified by the University of Minnesota^[69][70] and the University of Baltimore^[68] are solved. Usability will be one of the main improvements in Drupal 7 that will close the gap with easier CMSs.

• Learning curve: Some users have described Drupal as being fairly difficult to master.^[65][71][72]

• Backward compatibility (for software development): Drupal's designers have decided that, in terms of programming, backward compatibility may be sacrificed with each major revision.^[73] As a result, sometimes a new version's code is not compatible with a previous version. This means that contrib module and theme developers may be required to re-work some or all of their previous code to ensure compatibility with the latest version of Drupal. However, the policy enforced for Drupal core development is that Drupal may change an API, but it will not change how it uses your data. This means that while code may need changing between major releases, data from previous versions will still be usable without the need to alter the data itself in the new release.^[74][75] This could also be considered a feature, since many systems try to maintain legacy code for backwards compatibility, causing bloat. Drupal, by comparison, allows incompatibility, but any occurrences of this are clearly marked, allowing the user to make informed decisions about when and whether to upgrade.
• Performance/scalability: In 2008, performance tests between Drupal 6.1 and Joomla 1.5 demonstrated that Drupal's Web pages were delivered "significantly faster" than those of Joomla.^[76] Despite this, there persists a popular view that Drupal is slow.^[77] It is true that Drupal is likely to be slower when configured for a narrow usage as compared to an application specifically designed for that usage. For example, Wordpress may often outperform Drupal as a single-user blogging tool. However, the Drupal project itself suggests that narrowly focused applications are often preferable for narrow usage.^[78] To improve performance, Drupal offers caching to store various elements of pages, the use of which resulted in a 508% improvement. Static pages are typically delivered to only anonymous visitors; contributed modules must be installed to allow caching for logged in users.^[79] Thus, dramatic performance improvements from caching may not reflect real-world usage of some Drupal sites.^[80] Like performance, scalability, or the ability for a Web site to handle a growing number of visitors, can become a concern on large, interactive sites. Particularly, database (MySQL) query caching can help offset the load to the database server caused by Drupal's high query rate.^[81][82] Since version 6, Drupal caches database schema as well as elements such as blocks, forms and menus.^[83] Development versions of Drupal 7 increase performance in database queries with simultaneous performance decreases in PHP code usage.^[84]

Examples

These are examples of websites based on the Drupal CMS:

Further reading

• Beighley, Lynn (2009). Drupal for Dummies. New York: For Dummies. ISBN 978-0-470-55611-5. 
• Douglass, Robert T.; Mike Little and Jared W. Smith (2005). Building Online Communities With Drupal, phpBB, and WordPress. New York: Springer Verlag/Apress. ISBN 1-590-59562-9. 
• Mercer, David (2006). Drupal: Creating Blogs, Forums, Portals, and Community Websites. Birmingham, England: Packt Publishing. ISBN 1-904-81180-9. 
• Peacock, Michael (2008). Selling Online with Drupal e-Commerce. Birmingham, England: Packt Publishing. ISBN 978-1-847194-06-0. 
• Charlton, Chris (2007). Advanced Flex Application Development: Building Rich Media X with Drupal 5 & Flex 2. London, England: Friends of ED/Apress. ISBN 978-1590598962. 
• Roswell, Marjorie (2009). Drupal 5 Views Recipes. Birmingham, England: Packt Publishing. ISBN 978-1847196965. 
• Shreves, Ric (2007). Drupal 5 Themes. Birmingham, England: Packt Publishing. ISBN 1-847-19182-7. 
• VanDyk, John K. (2008). Pro Drupal Development, Second Edition. New York: Springer Verlag/Apress. ISBN 1-430-20989-5. 
• Herremans, D. (2009). Drupal 6: Ultimate Community Site Guide. Switzerland. ISBN 978-2-839-90490-2. 

See also

• List of content management systems
• List of web application frameworks
• Web application frameworks

Notes

External links

• Official website