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 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.[35] 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.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".