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Web application framework

Web Design & Development Guide

Web application framework

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List of web application frameworks


A web application framework is a software framework that is designed to support the development of dynamic websites, Web applications and Web services. The framework aims to alleviate the overhead associated with common activities used in Web development. For example, many frameworks provide libraries for database access, templating frameworks and session management, and often promote code reuse.

History

Common Gateway Interface

As the design of the World Wide Web was not inherently dynamic, early hypertext consisted of hand-coded HTML that was published on web servers. Any modifications to published pages needed to be performed by the pages' author. To provide a dynamic web page that reflected user inputs, the Common Gateway Interface (CGI) standard was introduced for interfacing external applications with web servers.[1] CGI could adversely affect server load, though, since each request had to start a separate process.

Tighter integration

Programmers wanted tighter integration with the web server to enable high traffic web applications. The Apache HTTP Server, for example, supports modules that can extend the web server with arbitrary code executions (such as mod_python) or forward specific requests to a web server that can handle dynamic content (such as mod_jk). Some web servers (such as Apache Tomcat) were specifically designed to handle dynamic content by executing code written in some languages, such as Java.

Web languages

Around the same time, new languages were being developed specifically for use in the web, such as PHP and Active Server Pages.

Web libraries

While the vast majority of languages available to programmers to use in creating dynamic web pages have libraries to help with common tasks, web applications often require specific libraries that are useful in web applications, such as creating HTML (for example, JavaServer Faces).

Full Stack

Eventually, mature, "full stack" frameworks appeared, that often gathered multiple libraries useful for web development into a single cohesive software stack for web developers to use.

Architectures

Model view controller

Many frameworks follow the Model View Controller (MVC) architectural pattern to separate the data model, business rules and user interface.

Push-based vs. Pull-based

Most MVC frameworks follow a push-based architecture. These frameworks use actions that do the required processing, and then "push" the data to the view layer to render the results.[2] Struts and Ruby on Rails are good examples of this architecture.

An alternative to this is pull-based architecture, sometimes also called "component-based". These frameworks start with the view layer, which can then "pull" results from multiple controllers as needed. In this architecture, multiple controllers can be involved with a single view. Tapestry and JBoss Seam are examples of pull-based architectures.

Features

Security

Some web application frameworks come with authentication and authorization frameworks, that enable the web server to identify the users of the application, and restrict access to functions based on some defined criteria. Django is one example that provides role-based access to pages, and provides a web-based interface for creating users and assigning them roles.

Database access and mapping

Many web application frameworks create a unified API to a database backend, enabling web applications to work with a variety of databases with no code changes, and allowing programmers to work with higher-level concepts. Additionally, some object-oriented frameworks contain mapping tools to provide Object-Relational Mapping, which will map objects to tuples.

Other features web application frameworks may provide include transactional support and database migration tools.

URL mapping

By automatically rewriting a url with parameters to a friendly URL, the system becomes easier to use, and as an additional benefit, is better indexed by search engines. An example would be the address ending in ?cat=1&pageid=3 to /category/science/topic/physics or just /science/physics. When the id of the category changes the url can stay the same (hence the advantage for search engines). Rewriting URL's can help make an application better conform to some elements of RESTful design practices.

Web template system

Dynamic web pages usually consist of a static part (HTML) and a dynamic part, which is code that generates HTML. The code that generates the HTML can do this based on variables in a template, or on code. The text to be generated can come from a database, thereby making it possible to dramatically reduce the number of pages in a site.

Consider the example of a real estate agent with 500 houses for sale. In a static web site, the agent would have to create 500 pages in order to make the information available. In a dynamic website, the agent would simply connect the dynamic page to a database table of 500 records.

In a template, variables from the programming language can be inserted without using code, thereby losing the requirement of programming knowledge to make updates to the pages in a web site. A syntax is made available to distinguish between HTML and variables. E.g. in JSP the <c:out> tag is used to output variables, and in Smarty, {$variable} is used.

Many template engines do support limited logic tags, like IF and FOREACH. These are to be used only for decisions that need to be made for the presentation layer, in order to keep a clean separation from the business logic layer, or the M(odel) in the MVC pattern.

Some frameworks will generate a basic, but fully-functional, application, once the developer specifies the structure of the data, or it is discovered through introspection. In some frameworks, this scaffolding supports the create, read, update and delete (CRUD) operations necessary to manipulate data.

Caching

Web caching is the caching of web documents in order to reduce bandwidth usage, server load, and perceived "lag". A web cache stores copies of documents passing through it; subsequent requests may be satisfied from the cache if certain conditions are met. Some application frameworks provide mechanisms for caching documents and bypassing the web template system.

Ajax

Ajax, shorthand for "Asynchronous JavaScript and XML", is a web development technique for creating interactive web applications. The intent is to make web pages feel more responsive by exchanging small amounts of data with the server behind the scenes, so that the entire web page does not have to be reloaded each time the user requests a change. This is intended to increase the web page's interactivity, speed, and usability.

Due to complexity of Ajax programming, there are numerous Ajax frameworks that exclusively deal with Ajax support. Some Ajax frameworks are even embedded as a part of larger frameworks. For example, the Prototype JavaScript Framework is included in Ruby on Rails.

Automatic configuration

Some frameworks minimize web application configuration through the use of introspection and/or following known conventions. For example, many Java frameworks use Hibernate as a persistence layer, which can generate a database schema at runtime capable of persisting the necessary information. This allows the application designer to design business objects without needing to explicitly define a database schema. Frameworks such as Ruby on Rails can also work in reverse, that is, define properties of model objects at runtime based on a database schema.

Web services

Main article: Web services

Some frameworks provide tools for creating and providing web services. These utilities may offer similar tools as the rest of the web application.

Technologies

See also: List of web application frameworks

Languages

Many languages have an associate web application framework. However, certain languages either have a critical mass of developers to give a higher level of support to frameworks, or provide features that prove conducive to the development of web application frameworks

Java

There are numerous Java frameworks either in development or in use. Many of these frameworks are built on top of, or borrow elements from the Java EE platform.

ASP.NET

For Microsoft's ASP.NET platform there is the DotNetNuke web application framework. Since ASP.NET itself is a technology designed for building web apps it's often wrongly referred to as a web application framework.

PHP

PHP's original design for dynamic web pages has given support to projects such as CakePHP, symfony, Zoop_Framework, the eZ publish web publishing framework and the Zend Framework.

Perl, Python and Ruby

There are numerous dynamic language frameworks. Perl has Maypole and Catalyst. Python has Django, TurboGears, pylons, Quixote, and Karrigell. Ruby has Nitro and Ruby on Rails, a particularly well known framework.

Smalltalk

Seaside is an open source web application framework for developing web applications in Smalltalk. Although the main development of Seaside happens in Squeak there exist ports for other Smalltalk dialects.

JavaScript

Helma is an open source web application framework / publishing system written in Java which uses Javascript as programming language.

Operating Systems

With very few exceptions, web application frameworks are based upon platform independent languages that run on a variety of platforms. While some frameworks may recommend particular configurations, most can run on Windows, Linux, Mac and other Unix-based platforms. A notable exception is DotNetNuke, written for the .NET Framework, that does not support the Mono runtime.

References

  1. ^ CGI: Common Gateway Interface.
  2. ^ Thomson, Kris (2003-10-29). Clarification on MVC Pull and MVC Push.

See also


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