Web application: Difference between revisions

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In [[software engineering]], a '''Web application''' or '''webapp''' is an [[Application software|application]] that is accessed via web over a network such as the [[Internet]] or an [[intranet]].

{{short description|Application that uses a web browser as a client}}

{{Multiple issues|

{{More citations needed|date=February 2018}}

{{Original research|date=May 2022}}

{{Cleanup rewrite|reason=quality standards|date=May 2022}}

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[[File:Horde-portal.png|thumb|Screenshot from 2007 of [[Horde (software)|Horde]], a groupware and open-source web application]]

A '''web application''' (or '''web app''') is [[application software]] that is created with [[World Wide Web|web technologies]] and runs via a [[web browser]].<ref name="britannica" /><ref name="aws-web-app" /> Web applications emerged during the late 1990s and allowed for the server to [[Dynamic web page|dynamically]] build a response to the request, in contrast to [[Static web page|static web pages]].<ref name="docforge-web-app" />

Web applications are commonly distributed via a [[web server]]. There are several different tier systems that web applications use to communicate between the web browsers, the client interface, and server data. Each system has its own uses as they function in different ways. However, there are many security risks that developers must be aware of during development; proper measures to protect user data are vital.

Web applications are popular due to the ubiquity of a [[client (computing)|client]], sometimes called a [[thin client]]. The ability to update and maintain Web applications without distributing and installing software on potentially thousands of client computers is a key reason for their popularity. Web applications are used to implement [[Webmail]], online [[retail sales]], [[online auction]]s, [[wiki]]s, [[Internet forum|discussion boards]], [[Weblog]]s, [[MMORPG]]s and many other functions.

Web applications are often constructed with the use of a [[web application framework]]. [[Single-page application|Single-page applications (SPAs)]] and [[Progressive web app|progressive web apps (PWAs)]] are two architectural approaches to creating web applications that provide a [[user experience]] similar to [[Native (computing)|native apps]], including features such as smooth navigation, offline support, and faster interactions.

==History==

In earlier types of [[client-server]] computing, each application had its own client program which served as its [[user interface]] and had to be separately installed on each user's [[personal computer]]. An upgrade to the server part of the application would typically require an upgrade to the clients installed on each user workstation, adding to the [[technical support|support]] cost and decreasing [[productivity]].

Web applications are often fully hosted on remote [[cloud service]]s, can require a constant connection to them, and can replace conventional desktop applications for operating systems such as [[Microsoft Windows]], thus facilitating the operation of [[software as a service]] as it grants the developer the power to tightly control billing based on use of the remote services as well as vendor lock-in by hosting data remotely. Modern browsers such as Chrome offer sandboxing for every browser tab which improves security and restricts access to local resources. No software installation is required as the app runs within the browser which reduces the need for managing software installations. With the use of remote cloud services, customers do not need to manage servers as that can be left to the developer and the cloud service and can use the software with a relatively low power, low-resource PC such as a [[thin client]]. The source code of the application can stay the same across operating systems and devices of users with the use of [[responsive web design]], since it only needs to be compatible with web browsers which adhere to web standards, making the code highly portable and saving on development time. Numerous [[Comparison of JavaScript-based web frameworks| JavaScript frameworks]] and [[CSS frameworks]] facilitate development.

In contrast, Web applications dynamically generate a series of [[Web document]]s in a standard format supported by common browsers such as [[HTML]]/[[XHTML]]. [[Client-side scripting]] in a standard language such as [[JavaScript]] is commonly included to add dynamic elements to the user interface. Generally, each individual Web page is delivered to the client as a static document, but the sequence of pages can provide an interactive experience, as user input is returned through Web [[form]] elements embedded in the page markup. During the session, the Web browser interprets and displays the pages, and acts as the ''universal'' client for any Web application.

==InterfaceHistory==

The concept of a "web application" was first introduced in the Java language in the Servlet Specification version 2.2, which was released in 1999. At that time, both JavaScript and [[XML]] had already been developed, but the [[XMLHttpRequest]] object had only been recently introduced on Internet Explorer 5 as an [[ActiveX]] object.{{citation needed|date=May 2025}} Beginning around the early 2000s, applications such as "[[Myspace]] (2003), [[Gmail]] (2004), [[Digg]] (2004), [and] [[Google Maps]] (2005)," started to make their client sides more and more interactive. A web page script is able to contact the server for storing/retrieving data without downloading an entire web page. The practice became known as Ajax in 2005. Eventually this was replaced by [[web API]]s using [[JSON]], accessed via [[JavaScript]] asynchronously on the client side.

The Web interface places very few limits on client functionality. Through [[Java (Sun)|Java]], [[JavaScript]], [[DHTML]], [[Adobe Flash|Flash]] and other technologies, application-specific methods such as drawing on the screen, playing audio, and access to the keyboard and mouse are all possible. Many services have worked to combine all of these into a more familiar interface that adopts the appearance of an operating system. General purpose techniques such as [[drag and drop]] are also supported by these technologies. Web developers often use client-side scripting to add functionality, especially to create an interactive experience that does not require page reloading (which many users find disruptive). Recently, technologies have been developed to coordinate client-side scripting with server-side technologies such as [[PHP]]. [[Ajax (programming)|Ajax]], a web development technique using a combination of various technologies, is an example of technology which creates a more interactive experience.

In earlier computing models like client-server, the processing load for the application was shared between code on the server and code installed on each client locally. In other words, an application had its own pre-compiled client program which served as its [[user interface]] and had to be separately installed on each user's [[personal computer]]. An upgrade to the server-side code of the application would typically also require an upgrade to the client-side code installed on each user workstation, adding to the [[Technical support|support]] cost and decreasing [[productivity]]. Additionally, both the client and server components of the application were bound tightly to a particular [[computer architecture]] and [[operating system]], which made [[porting]] them to other systems prohibitively expensive for all but the largest applications.

==Technical considerations==

A significant advantage of building Web applications to support standard browser features is that they should perform as specified regardless of the operating system or OS version installed on a given client. Rather than creating clients for [[Microsoft Windows|MS Windows]], [[Mac OS X]], [[Linux|GNU/Linux]], and other [[operating system]]s, the application can be written once and deployed almost anywhere. However, inconsistent implementations of the [[HyperText Markup Language|HTML]], [[Cascading Style Sheets|CSS]], [[Document Object Model|DOM]] and other browser specifications can cause problems in web application development and support. Additionally, the ability of users to customize many of the display settings of their browser (such as selecting different font sizes, colors, and typefaces, or disabling scripting support) can interfere with consistent implementation of a Web application.

Later, in 1995, [[Netscape]] introduced the [[client-side scripting]] language called [[JavaScript]], which allowed programmers to add [[Dynamic HTML|dynamic elements]] to the user interface that ran on the client side. Essentially, instead of sending data to the server in order to generate an entire web page, the embedded scripts of the downloaded page can perform various tasks such as [[Data validation|input validation]] or showing/hiding parts of the page.

Another (less common) approach is to use [[Adobe Flash]] or [[Java applet]]s to provide some or all of the user interface. Since most Web browsers include support for these technologies (usually through plug-ins), Flash- or Java-based applications can be implemented with much of the same ease of deployment. Because they allow the programmer greater control over the interface, they bypass many browser-configuration issues, although incompatibilities between Java or Flash implementations on the client can introduce different complications. Because of their architectural similarities to traditional client-server applications, with a somewhat "thick" client, there is some dispute over whether to call systems of this sort "Web applications"; an alternative term is "[[Rich Internet Application]]".

"[[Progressive web app|Progressive web apps]]", the term coined by designer Frances Berriman and [[Google Chrome]] engineer Alex Russell in 2015, refers to apps taking advantage of new features supported by modern browsers, which initially run inside a web browser tab but later can run completely offline and can be launched without entering the app URL in the browser.

==Structure==

{{Primary sources|section|date=November 2022}}

Though many variations are possible, a Web application is commonly structured as a [[Three-tier (computing)|three-tiered]] application. In its most common form, a Web browser is the first tier, an engine using some dynamic Web content technology (such as [[Active Server Pages|ASP]], [[ASP.NET]], [[Common Gateway Interface|CGI]], [[ColdFusion]], [[Java Servlet|JSP/Java]], [[PHP]], [[Python]], or [[Ruby On Rails]]) is the middle tier, and a database is the third tier. The Web browser sends requests to the middle tier, which services them by making queries and updates against the database and generates a user interface.

Traditional PC applications are typically single-tiered, residing solely on the client machine. In contrast, web applications inherently facilitate a multi-tiered architecture. Though many variations are possible, the most common structure is the [[Three-tier (computing)|three-tiered]] application. In its most common form, the three tiers are called ''presentation'', ''application'' and ''storage''. The first tier, presentation, refers to a web browser itself. The second tier refers to any engine using dynamic web content technology (such as [[Active Server Pages|ASP]], [[Common Gateway Interface|CGI]], [[ColdFusion]], [[Dart (programming language)|Dart]], [[Java Servlet|JSP/Java]], [[Node.js]], [[PHP]], [[Python (programming language)|Python]] or [[Ruby on Rails]]). The third tier refers to a database that stores data and determines the structure of a user interface. Essentially, when using the three-tiered system, the web browser sends requests to the engine, which then services them by making queries and updates against the database and generates a user interface.

The 3-tier solution may fall short when dealing with more complex applications, and may need to be replaced with the n-tiered approach; the greatest benefit of which is how [[business logic]] (which resides on the application tier) is broken down into a more fine-grained model.<ref name="ntiered" /> Another benefit would be to add an integration tier, which separates the data tier and provides an easy-to-use interface to access the data.<ref name="ntiered" /> For example, the client data would be accessed by calling a "list_clients()" function instead of making an [[SQL]] query directly against the client table on the database. This allows the underlying database to be replaced without making any change to the other tiers.<ref name="ntiered" />

==Business use==

An emerging strategy for application software companies is to provide Web access to software previously distributed as local applications. Depending on the type of application, it may require the development of an entirely different browser-based interface, or merely adapting an existing application to use different presentation technology. These programs allow the user to pay a monthly or yearly fee for use of a software application without having to install it on a local hard drive. A company which follows this strategy is known as an [[application service provider]] (ASP), and ASPs are currently receiving much attention in the software industry.

There are some who view a web application as a two-tier architecture. This can be a "smart" client that performs all the work and queries a "dumb" server, or a "dumb" client that relies on a "smart" server.<ref name="ntiered" /> The client would handle the presentation tier, the server would have the database (storage tier), and the business logic (application tier) would be on one of them or on both.<ref name="ntiered" /> While this increases the scalability of the applications and separates the display and the database, it still does not allow for true specialization of layers, so most applications will outgrow this model.<ref name="ntiered" />

==Writing Web applications==

There are many [[Web application framework]]s which facilitate rapid application development by allowing the programmer to define a high-level description of the program. In addition, there is potential for the development of applications on [[Internet Operating Systems]], although currently there are not many viable platforms that fit this model.

==Security==

The use of Web application frameworks can often reduce the number of errors in a program, both by making the code more simple, and by allowing one team to concentrate just on the framework. In applications which are exposed to constant [[Hacker#Hacker: Intruder and criminal|hacking]] attempts on the Internet, security-related problems caused by errors in the program are a big issue. Frameworks may also promote the use of best practices such as [[Post/Redirect/Get|GET after POST]]

{{Main|Internet security}}

{{More citations needed section|date=February 2018}}

Security breaches on these kinds of applications are a major concern because it can involve both enterprise information and private customer data. Protecting these assets is an important part of any web application, and there are some key operational areas that must be included in the development process.<ref name="dell-secure" /> This includes processes for authentication, authorization, asset handling, input, and logging and auditing. Building security into the applications from the beginning is sometimes more effective and less disruptive in the long run.

==Development==

The [http://www.webappsec.org Web Application Security Consortium] (WASC), [http://www.cgisecurity.com CGI Security], and [http://www.owasp.org OWASP] are projects developed with the intention of documenting how to avoid security problems in Web applications.

Writing web applications is simplified with the use of [[web application frameworks]]. These frameworks facilitate [[rapid application development]] by allowing a development team to focus on the parts of their application which are unique to their goals without having to resolve common development issues such as user management.<ref name="docforge" />

In addition, there is potential for the development of applications on [[Internet operating system]]s, although currently there are not many viable platforms that fit this model.{{cn|date=November 2022|reason=Possibly undue, a source establishing weight of this in web application development overall is needed.}}

==See also==

{{portal|Internet}}

{|

* [[Web API]]

|- valign=top

* [[Software as a service|Software as a service (SaaS)]]

| width=50% |

* [[AJAXWeb 2.0]]

* [[Web engineering]]

*[[Active Server Pages|ASP]] (Active Server Pages)

* [[Web GIS]]

*[[Application service provider|ASP]] (Application Service Provider)

* [[AlphaWeb Fiveservice]]s

* [[ASP.NETWeb science]]s

* [[Web widget]]

*[[Cascading Style Sheets|CSS]]

*[[ColdFusion]]

==References==

*[[Content management framework]]

{{Reflist|refs=

*[[Dynamic HTML|DHTML]]

*[[Hypertext Markup Language|HTML]]

<ref name="britannica">{{cite web |title=Web app {{!}} Definition, History, Development, Examples, Uses, & Facts {{!}} Britannica |url=https://www.britannica.com/topic/Web-application |website=www.britannica.com |publisher=Encyclopædia Britannica |access-date=4 November 2024 |language=en}}</ref>

*[[Web document|Dynamic web document]]

*[[JavaScript]]

<ref name="docforge-web-app">{{cite web |title=Web applications |url=http://docforge.com/wiki/Web_application |website=DocForge |access-date=9 November 2024 |archive-url=https://web.archive.org/web/20150419035250/http://docforge.com/wiki/Web_application |archive-date=19 April 2015}}</ref>

| width=50% |

*[[JavaServer Pages|JSP]]

<ref name="aws-web-app">{{cite web |title=What is a Web App? - Web Application Explained - AWS |url=https://aws.amazon.com/what-is/web-application/ |website=Amazon Web Services, Inc. |access-date=4 November 2024}}</ref>

*[[Ruby On Rails]]

*[[Perl]]

<ref name="ntiered">{{Cite web |url=http://krunal-ajax-javascript.blogspot.bg/2008/09/benefits-of-using-n-tiered-approach-for.html |title=Benefits of using the n-tiered approach for web applications |last=Petersen |first=Jeremy |date=4 September 2008 |access-date=24 November 2017 |archive-date=1 December 2017 |archive-url=https://web.archive.org/web/20171201080946/http://krunal-ajax-javascript.blogspot.bg/2008/09/benefits-of-using-n-tiered-approach-for.html |url-status=live }}</ref>

*[[PHP]]

*[[Python (programming language)|Python]]

<ref name="dell-secure">{{cite web|url= http://content.dell.com/us/en/enterprise/d/large-business/secure-app-development.aspx|title= Top Tips for Secure App Development|publisher= Dell.com|access-date= 2012-06-22|archive-url= https://web.archive.org/web/20120522022522/http://content.dell.com/us/en/enterprise/d/large-business/secure-app-development.aspx|archive-date= 2012-05-22|url-status= dead}}</ref>

*[[Software development]]

*[[Web 2.0]]

<ref name="docforge">{{cite web | url=http://docforge.com/wiki/Web_application_framework | title=Web application framework | author=Multiple (wiki) | work=Docforge | access-date=2010-03-06 | archive-date=2020-06-20 | archive-url=https://web.archive.org/web/20200620213429/http://www.docforge.com/wiki/Web_application_framework | url-status=dead }}</ref>

*[[Software as a service|SaaS]]

*[[Web application framework]]

}}

*[[Web service]]s

*[[List of web application frameworks]]

*[[World Wide Web Consortium]] (Web standards)

|

|}

==External links==

*[http://www.joelonsoftwarewhatwg.comorg/articlesspecs/web-apps/current-work/multipage/APIWar.html HowHTML5 MicrosoftDraft lostrecommendation], the APIchanges war]to &mdash;HTML Aand discussionrelated onAPIs howto webease applicationsauthoring areof replacing Windowsweb-based applications.

*[http://www.whatwgw3.org/specs2008/web-apps/current-workwebapps/ Web Applications 1.0Working Group] isat the ongoing[http://www.w3.org/ workWorld of documenting howWide Web applicationsConsortium] will work.(W3C)

*[https://web.dev/progressive-web-apps/ PWAs on Web.dev] by [[Google Developers]].

*[http://www.paulgraham.com/road.html The Other Road Ahead] &mdash; An article arguing that the future lies on the server, not rich interfaces on the client

*[http://dmoz.org/Computers/Internet/On_the_Web/Web_Applications/ Web Applications] in the [[Open Directory Project]]

*[http://msdn.microsoft.com/webclientfactory Web Client Software Factory] &mdash; A discussion on how to create composite web and page flow applications on the Microsoft platform.

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