What is World Wide Web 2.0

Web 2.0, a phrase coined by O’Reilly Media in 2004, refers to a supposed second-generation of Internet-based services — such as social networking sites, wikis, communication tools, and folksonomies — that let people collaborate and share information online in previously unavailable ways. O’Reilly Media, in collaboration with MediaLive International, used the phrase as a title for a series of conferences and since then it has become a popular (though ill-defined and often criticized) buzzword amongst certain technical and marketing communities.

The complex and evolving technology infrastructure of Web 2.0 includes server-software, content-syndication, messaging-protocols, standards-based browsers with plugins and extensions, and various client-applications. These differing but complementary approaches provide Web 2.0 with information-storage, creation, and dissemination capabilities that go beyond what the public formerly expected of websites.

A Web 2.0 website typically features a number of the following techniques:

• Unobtrusive rich Internet application techniques (such as [Adobe Flash/Flex])
• CSS
• Semantically valid XHTML markup and/or the use of Microformats
• Syndication and aggregation of data in RSS/Atom
• Clean and meaningful URLs
• Weblog publishing
• Mashups
• REST or XML Webservice APIs

Rich Internet applications

Main article: Rich Internet application

Recently, rich-Internet application techniques such as Ajax, Adobe Flash and Flex have evolved that can improve the user-experience in browser-based web applications. Flash/Flex involves a web-page requesting an update for some part of its content, and altering that part in the browser, without refreshing the whole page at the same time.

Server-side software

The functionality of Web 2.0 rich Internet applications builds on the existing web server architecture, but puts much greater emphasis on back-end software. Syndication differs only nominally from the methods of publishing using dynamic content management, but web services typically require much more robust database and workflow support, and become very similar to the traditional intranet functionality of an application server. Vendor approaches to date fall under either a universal server approach, which bundles most of the necessary functionality in a single server platform, or a web-server plugin approach, which uses standard publishing tools enhanced with API interfaces and other tools.

Client-side software

The extra functionality provided by Web 2.0 depends on the ability of users to work with the data stored on servers. This can come about through forms in an HTML page, through a scripting language such as Javascript, or through Flash or Java. These methods all make use of the client computer to reduce the server workload.

RSS

Main article: RSS (file format)

The first and the most important step (in one view) of the evolution towards Web 2.0 involves the syndication of website content, using standardized protocols which permit end-users to make use of a site’s data in another context, ranging from another website, to a browser plugin, or to 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 flavors of XML. Specialized protocols such as FOAF and XFN (both for social networking) extend functionality of sites or permit end-users to interact without centralized websites. See microformats for more specialized data formats.

Due to the recent development of these trends, many of these protocols remain de facto (rather than formal) standards.

Web protocols

Web communication protocols provide a key element of the Web 2.0 infrastructure. Major protocols include REST and SOAP.

• REST (Representational State Transfer) indicates a way to access and manipulate data on a server using the HTTP verbs GET, POST, PUT, and DELETE
• SOAP involves POSTing XML messages and requests to a server that may contain quite complex, but pre-defined, instructions for the server to follow

In both cases, an API defines access to the service. Often this API is specific to the server, but standard web service APIs (for example, for posting to a blog) are also widely used. Most, but not all, communications with web services involve some form of XML (eXtensible Markup Language).

See also WSDL (Web Services Description Language) (the standard way of publishing a SOAP API) and the list of Web service specifications for links to many other web service standards, including those many whose names begin ‘WS-’.