WEB 2.0 TECHNOLOGIES

Web 2.0 can be defined as the web development and web design that facilitates interactive in sharing the information, user-centered and the combination on the World Wide Web. It is also known as loose collection of information technologies and applications, and of the web sites that use them. The applications of web 2.0 are XML, AJAX, tagging, blogs, wikis, Really Simple Indication, podcasting and video casting. AJAX is a Web development technique that allows portions of the Web pages to reload with fresh data instead of requiring the entire Web page to reload. This process speeds up response time and increases user satisfaction. A tag is a keyword that describes a piece of information. Tagging allows users to place information in multiple associations rather than in rigid categories. While, a weblog(blog) is a personal website, for public to express his feelings or opinions. The blogosphere is the term for the millions of blogs on the Web. Then, a wiki is a Web site on which anyone can post material and make changes to other material. Really Simple Syndication (RSS) allows users to receive the information they want, when they want it, without having to surf thousands of Web sites. It is also allows anyone to publish his blog and the other content, to anyone who has an interest in subscribing. Next, a podcast is a digital audio file that is distributed over the Web using RSS for playback on portable media players on personal computers. A video cast is the same as podcast.



There are several types of Web 2.0. There are social media, aggregators, and mashups. The first types is social networking is the Web 2.0 that allows users to upload their content to the Web, in the form of text, voice, images, and videos. It provides an easy and interactive way to communicate and cooperate with on others on the web. It is also useful to help small business around the world. Secondly, an aggregator is the Web sites that provide collections of content from the Web. Lastly, mashup means to mix and match content from other parts of the Web. It can be defined as a Web site that takes content from a number of other Web sites and mixes them together to create a new kind of content.

The term "Web 2.0" is commonly associated with web applications which facilitate interactive information sharing, interoperability, user-centered design and collaboration on the World Wide Web. Examples of Web 2.0 include web-based communities, hosted services, web applications, social-networking sites, video-sharing sites, wikis, blogs, mashups and folksonomies. A Web 2.0 site allows its users to interact with other users or to change website content, in contrast to non-interactive websites where users are limited to the passive viewing of information that is provided to them.

The term is closely associated with Tim O'Reilly because of the O'Reilly Media Web 2.0 conference in 2004.Although the term suggests a new version of the World Wide Web, it does not refer to an update to any technical specifications, but rather to cumulative changes in the ways software developers and end-users use the Web. Whether Web 2.0 is qualitatively different from prior web technologies has been challenged by World Wide Web inventor Tim Berners-Lee who called the term a "piece of jargon".

How it works
The client-side/web browser technologies typically used in Web 2.0 development are Asynchronous JavaScript and XML (Ajax), Adobe Flash, and JavaScript/Ajax frameworks such as Yahoo! UI Library, Dojo Toolkit, MooTools, and jQuery. Ajax programming uses JavaScript to upload and download new data from the web server without undergoing a full page reload, hence the term "asynchronous."
The data fetched by an Ajax request is typically formatted in XML or JSON (JavaScript Object Notation) format, two widely used structured data formats. Since both of these formats are natively understood by JavaScript, a programmer can easily use them to transmit structured data in their web application. When this data is received via Ajax, the JavaScript program then uses the Document Object Model (DOM) to dynamically update the web page based on the new data, allowing for a rapid and interactive user experience. In short, using these techniques, Web designers can make their pages function like desktop applications. For example, Google Docs uses this technique to create a Web-based word processor.
Adobe Flash is another technology often used in Web 2.0 applications. As a widely available plugin independent of W3C (World Wide Web Consortium, the governing body of web standards and protocols), standards, Flash is capable of doing many things which are not currently possible in HTML, the language used to construct web pages. Of Flash's many capabilities, the most commonly used in Web 2.0 is its ability to play audio and video files. This has allowed for the creation of Web 2.0 sites such as YouTube, where video media is seamlessly integrated with standard HTML.
In addition to Flash and Ajax, JavaScript/Ajax frameworks have recently become a very popular means of creating Web 2.0 sites. At their core, these frameworks do not use technology any different from JavaScript, Ajax, and the DOM. What frameworks do is smooth over inconsistencies between web browsers and extend the functionality available to developers. Many of them also come with customizable, prefabricated 'widgets' that accomplish such common tasks as picking a date from a calendar, displaying a data chart, or making a tabbed panel.

On the server side, Web 2.0 uses many of the same technologies as Web 1.0. Languages such as PHP, Ruby, Perl, Python, and ASP are used by developers to dynamically output data using information from files and databases. What has begun to change in Web 2.0 is the way this data is formatted. In the early days of the internet, there was little need for different websites to communicate with each other and share data. In the new "participatory web," however, sharing data between sites has become an essential capability. To share its data with other sites, a web site must be able to generate output in machine-readable formats such as XML, RSS, and JSON. When a site's data is available in one of these formats, another website can use it to integrate a portion of that site's functionality into itself, linking the two together. When this design pattern is implemented, it ultimately leads to data that is both easier to find and more thoroughly categorized, a hallmark of the philosophy behind the Web 2.0 movement.

Usage
The popularity of the term Web 2.0, along with the increasing use of blogs, wikis, and social networking technologies, has led many in academia and business to coin a flurry of 2.0s, including Library 2.0, Social Work 2.0, Enterprise 2.0, PR 2.0, Classroom 2.0, Publishing 2.0, Medicine 2.0, Travel 2.0, Government 2.0, and even Porn 2.0. Many of these 2.0s refer to Web 2.0 technologies as the source of the new version in their respective disciplines and areas. For example, in the Talis white paper "Library 2.0: The Challenge of Disruptive Innovation," Paul Miller argues
Blogs, wikis and RSS are often held up as exemplary manifestations of Web 2.0. A reader of a blog or a wiki is provided with tools to add a comment or even, in the case of the wiki, to edit the content. This is what we call the Read/Write web.Talis believes that Library 2.0 means harnessing this type of participation so that libraries can benefit from increasingly rich collaborative cataloguing efforts, such as including contributions from partner libraries as well as adding rich enhancements, such as book jackets or movie files, to records from publishers and others. Here, Miller links Web 2.0 technologies and the culture of participation that they engender to the field of library science, supporting his claim that there is now a "Library 2.0." Many of the other proponents of new 2.0s mentioned here use similar methods.
Of course, not much time passed before "Web 3.0" was coined. Definitions of Web 3.0 vary. Amit Agarwal argues that it is the Semantic Web. Andrew Keen, author of The Cult of the Amateur, argues that Web 3.0 is the return of experts and authorities to the Web. For example, he points to Bertelsman's deal with the German Wikipedia to produce an edited print version of that encyclopedia. CNN Money's Jessi Hempel simply argues that Web 3.0 is Web 2.0 but with a profitable business model.

Web-based applications and desktops
Ajax has prompted the development of websites that mimic desktop applications, such as word processing, the spreadsheet, and slide-show presentation. WYSIWYG wiki sites replicate many features of PC authoring applications. Still other sites perform collaboration and project management functions. In 2006 Google, Inc. acquired one of the best-known sites of this broad class, Writely.
Several browser-based "operating systems" have emerged, including EyeOS and YouOS.Although coined as such, many of these services function less like a traditional operating system and more as an application platform. They mimic the user experience of desktop operating-systems, offering features and applications similar to a PC environment, as well as the added ability of being able to run within any modern browser. However, these operating systems do not control the hardware on the client's computer.
Numerous web-based application services appeared during the dot-com bubble of 1997–2001 and then vanished, having failed to gain a critical mass of customers. In 2005, WebEx acquired one of the better-known of these, Intranets.com, for $45 million. Internet applications
Main article: Rich Internet application XML and RSS
Advocates of "Web 2.0" may regard syndication of site content as a Web 2.0 feature, involving as it does standardized protocols, which permit end-users to make use of a site's data in another context (such as another website, a browser plugin, or a separate desktop application). Protocols which permit syndication include RSS (Really Simple Syndication — also known as "web syndication"), RDF (as in RSS 1.1), and Atom, all of them XML-based formats. Observers have started to refer to these technologies as "Web feed" as the usability of Web 2.0 evolves and the more user-friendly Feeds icon supplants the RSS icon.
Specialized protocols
Specialized protocols such as FOAF and XFN (both for social networking) extend the functionality of sites or permit end-users to interact without centralized websites.
Other protocols, like XMPP enables services to users like Services over the Messenger Web APIs
Machine-based interaction, a common feature of Web 2.0 sites, uses two main approaches to web APIs, which allow web-based access to data and functions: REST and SOAP.
REST (Representational State Transfer) web APIs use HTTP alone to interact, with XML (eXtensible Markup Language) or JSON payloads;
SOAP involves POSTing more elaborate XML messages and requests to a server that may contain quite complex, but pre-defined, instructions for the server to follow.
Often servers use proprietary APIs, but standard APIs (for example, for posting to a blog or notifying a blog update) have also come into wide use. Most communications through APIs involve XML or JSON payloads.
Web Services Description Language (WSDL) is the standard way of publishing a SOAP API and there are a range of Web Service specifications.
See also EMML by the Open Mashup Alliance for enterprise mashups.
Criticism
Critics of the term claim that "Web 2.0" does not represent a new version of the World Wide Web at all, but merely continues to use so-called "Web 1.0" technologies and concepts. First, techniques such as AJAX do not replace underlying protocols like HTTP, but add an additional layer of abstraction on top of them. Second, many of the ideas of Web 2.0 had already been featured in implementations on networked systems well before the term "Web 2.0" emerged. Amazon.com, for instance, has allowed users to write reviews and consumer guides since its launch in 1995, in a form of self-publishing. Amazon also opened its API to outside developers in 2002.Previous developments also came from research in computer-supported collaborative learning and computer-supported cooperative work and from established products like Lotus Notes and Lotus Domino, all phenomena which precede Web 2.0.
But perhaps the most common criticism is that the term is unclear or simply a buzzword. For example, in a podcast interview, Tim Berners-Lee described the term "Web 2.0" as a "piece of jargon":
"Nobody really knows what it means...If Web 2.0 for you is blogs and wikis, then that is people to people. But that was what the Web was supposed to be all along."Other critics labeled Web 2.0 “a second bubble” (referring to the Dot-com bubble of circa 1995–2001), suggesting that too many Web 2.0 companies attempt to develop the same product with a lack of business models. For example, The Economist has dubbed the mid- to late-2000s focus on Web companies "Bubble 2.0".Venture capitalist Josh Kopelman noted that Web 2.0 had excited only 53,651 people (the number of subscribers at that time to TechCrunch, a Weblog covering Web 2.0 startups and technology news), too few users to make them an economically viable target for consumer applications.Although Bruce Sterling reports he's a fan of Web 2.0, he thinks it is now dead as a rallying concept.
Critics have cited the language used to describe the hype cycle of Web 2.0 as an example of Techno-utopianist rhetoric.In terms of Web 2.0's social impact, critics such as Andrew Keen argue that Web 2.0 has created a cult of digital narcissism and amateurism, which undermines the notion of expertise by allowing anybody, anywhere to share - and place undue value upon - their own opinions about any subject and post any kind of content regardless of their particular talents, knowledgeability, credentials, biases or possible hidden agendas. He states that the core assumption of Web 2.0, that all opinions and user-generated content are equally valuable and relevant, is misguided and is instead "creating an endless digital forest of mediocrity: uninformed political commentary, unseemly home videos, embarrassingly amateurish music, unreadable poems, essays and novels," also stating that Wikipedia is full of "mistakes, half truths and misunderstandings".