Web application

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In computing, the web application or web application is a client-server computer program that the client (including user interface and client-side logic) runs on a web browser. Common web applications include webmail, online retail sales, online auctions, wikis, instant messaging services, and many other functions.

Video Web application

Similar definitions and terms

The general difference between dynamic web pages of any kind and "web apps" is unclear. Websites most commonly referred to as "web apps" are sites that have similar functionality to desktop software applications, or to mobile apps. HTML5 introduces explicit language support to create apps that are loaded as web pages, but can store data locally and continue to work offline.

One-page apps are more like apps because they reject the more typical web paradigm of moving between different pages with different URLs. One-page templates like Sencha Touch and AngularJS can be used to speed up the development of such web apps for mobile platforms.

Mobile web app

There are several ways to target mobile devices when creating web apps:

• Responsive web design can be used to create web applications - whether a conventional website or a one-page app can be viewed on a small screen and works well with the touch screen.
• Progressive Web App is a composite of regular web pages (or websites) and mobile apps.
• The native app or "mobile app" runs directly on mobile devices, just like conventional software applications run directly on desktop computers, without a web browser (and potentially without the need for Internet connectivity); this is usually written in Java (for Android devices) or Objective-C or Swift (for iOS devices). More recently, frameworks such as React Native, Flutter, and Xamarin allow the development of native applications for all platforms using languages ​​apart from any standard native language.
• Hybrid apps embed a mobile website inside native apps, possibly using hybrid frameworks like Apache Cordova and Ionic or Appcelerator Titanium. This allows development using web technologies (and may directly copy the code from existing mobile websites) while also maintaining certain benefits of native apps (eg direct access to device hardware, offline operations, app store visibility).

Maps Web application

History

In previous computing models such as client-server, the processing load for the application is shared between the code on the server and the code that is installed on each client locally. In other words, the app has its own pre-compiled client program that functions as a user interface and must be installed separately on each user's personal computer. Upgrading to the server-side code of an application will typically also require upgrading to client-side code installed on each user's workstation, increasing support costs and lowering productivity. In addition, both client and server application components are usually tightly bound to certain computer architectures and operating systems and ported to others are often expensive for all but the largest applications. (Currently, native apps for mobile devices are also hobbled by some or all of the previous issues.)

Instead, web apps use web documents written in standard formats such as HTML and JavaScript, which are supported by various web browsers. Web applications can be considered a specific variant of client server software where client software is downloaded to client computers when visiting relevant web pages, using standard procedures such as HTTP. Client client software updates can occur every time a web page is visited. During this session, the web browser interprets and displays the page, and acts as a universal client for each web application.

In the early days of the Web, each individual web page was sent to the client as a static document, but the order of the pages could still provide an interactive experience, as user input was returned via web form elements embedded in the page markup. However, any significant changes to the web page require a round-trip back to the server to refresh the entire page.

In 1995, Netscape introduced a client-side scripting language called JavaScript that allows programmers to add multiple dynamic elements to the client-side client interface. So instead of sending data to the server to generate all the web pages, embedded scripts from the downloaded page can perform various tasks such as input validation or display/hide parts of the page.

In 1996, Macromedia introduced Flash, a vector animation player that can be added to the browser as a plug-in to embed animations on web pages. This allows the use of a scripting language to program interactions on the client side without the need to communicate with the server.

In 1999, the concept of "web application" was introduced in the Java language in Servlet Specification version 2.2. [2.1?]. At that time both JavaScript and XML have been developed, but Ajax is still not created and the XMLHttpRequest object has just been introduced in Internet Explorer 5 as an ActiveX object.

In 2005, the term Ajax was created, and apps like Gmail started to make their client-side more interactive. Web page scripts can contact the server to store/retrieve data without downloading the entire web page.

In 2011, HTML5 was completed, which provides graphics and multimedia capabilities without the need for client-side plug-ins. HTML5 also enriches document semantic content. The API and document object (DOM) model is no longer an addition, but is a fundamental part of the HTML5 specification. The WebGL API paves the way for advanced 3D graphics based on HTML5 canvas and JavaScript language. It has significance in creating a platform that is truly a platform and a rich independent web application browser.

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Interface

Through Java, JavaScript, DHTML, Flash, Silverlight and other technologies, application-specific methods such as screen drawing, audio play, 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 look of the operating system. General purpose techniques such as drag and drop are also supported by this technology. Web developers often use client-side script to add functionality, especially to create interactive experiences that do not require page loading. Recently, technology has been developed to coordinate client-side scripts with server-side technologies such as ASP.NET, J2EE, Perl/Plack and PHP.

Ajax, a web development technique using a combination of technologies, is an example of technology that creates a more interactive experience.

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Structure

Applications are usually broken down into logical sections called "tier", where each level is assigned a role. Traditional apps consist of only 1 tier, which are on client machines, but web applications lend themselves to n-tier approach by nature. Although many variations are possible, the most common structure is a three-tier application. In the most common form, the three levels are called presentations , apps and storage , in this order. Web browsers are first-level (presentations), machines that use multiple dynamic Web content technologies (such as ASP, CGI, ColdFusion, Dart, JSP/Java, Node.js, PHP, Python, or Ruby on Rails) are mid-level (application logic ), and the database is the third level (storage). The web browser sends a request to the middle tier, which serves it by generating queries and updates to the database and generating the user interface.

For more complex applications, 3-tier solutions may fail, and may be useful for using n-tier approaches, where the greatest benefit is solving business logic, which is at the application level, becoming more refined models. Another benefit might be to add an integration level that separates the data level from the other levels by providing a convenient interface for data access. For example, client data will be accessed by calling the function "list_clients ()" instead of creating a SQL query directly against the client table in the database. This allows the underlying database to be replaced without making changes to another level.

There are some who see the web app as a two-tier architecture. This could be a "smart" client that does all the work and queries of a "dumb" server, or a "dumb" client that relies on a "smart" server. The client will handle the presentation tier, the server will have the database (storage level), and business logic (application tier) will be in one of them or both. While this improves the application scalability and separates the look and the database, it still does not allow for the actual layer specialization, so most applications will be larger than this model.

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Business use

The emerging strategy for enterprise application software is providing web access to software that was previously distributed as a local application. Depending on the type of application, this may require the development of completely different browser-based interfaces, or simply adapt existing applications to use different presentation technologies. These programs allow users to pay monthly or yearly fees for the use of software applications without having to install them on a local hard drive. Companies that follow this strategy are known as application service providers (ASPs), and ASP is currently receiving much attention in the software industry.

Security breaches in this type of application are of major concern as they may involve company information and personal customer data. Protecting these assets is an important part of web applications and there are several key operational areas to be included in the development process. This includes processes for authentication, authorization, asset handling, input, and logging and auditing. Building security into the application from scratch can be more effective and less intrusive in the long run.

The Cloud Computing model web app is software as a service (SaaS). There are business applications provided as SaaS for companies for fixed dependency fees or usage. Other web apps are offered for free, often generating revenue from ads shown in the web app interface.

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Development

Writing web applications is often simplified by using web application frameworks such as Django, Ruby on Rails, and Symfony. This framework facilitates rapid application development by enabling development teams to focus on their unique parts of the application for their purposes without having to resolve common development issues such as user management. Many of the frameworks used are open-source software.

The use of web application frameworks can often reduce the number of errors in a program, either by making the code simpler, and by allowing one team to concentrate on templates while the other focuses on the specified usage case. In applications that are exposed to constant hacking attempts on the Internet, security-related issues can be caused by errors in the program. Frameworks can also promote the use of best practices such as GET after POST.

In addition, there is potential for application development on Internet operating systems, although currently there are not many viable platforms that fit this model.

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Apps

Examples of browser applications are simple office software (word processors, online spreadsheets, and presentation tools), but can also include more powerful applications such as project management, computer-aided design, video editing, and point-of-sale.

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See also

• Software as a service (SaaS)
• Web 2.0
• Web Techniques
• Web services
• Web Science
• Web widgets
• One-page app
• Ajax (programming)
• Web development tools
• Browser game

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References

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External links

• Recommended HTML5 Design, changes to HTML, and related APIs to make web-based apps easier.
• The Other Road Ahead - An article stating that the future lies in the server, not the client-rich interface
• Web Application in Curlie (based on DMOZ)
• Web App Working Group on the World Wide Web Consortium (W3C)

Source of the article : Wikipedia