Скачать или смотреть Web-Feeds: RSS and Atom: Beyond the Blog Reader

Chapter 7 of the O'Reilly ebook "Learning API Styles" introduces the concept of web feeds, specifically the Atom and RSS formats used for asynchronous information delivery.

A web feed, also known as a news feed or syndication format, is a digital document that typically contains media such as web content updates (HTML) or links to other websites. It serves as a data format that delivers regularly updated information to users. Web feeds are used for asynchronous information distribution to keep users informed about new content such as news, blog posts, podcasts, or videos without requiring them to constantly check websites.

Although web feeds flourished around the year 2000, they are used less frequently today, primarily by news media, technology companies, bloggers, and academics. Their popularity declined as content migrated to login-protected social platforms like Meta or X. Nevertheless, web feeds remain relevant due to their historical significance and the use of XML.
Web feeds are a type of pull-based API, where the client requests data from the server. In some cases, the client frequently needs to know when new data is available, which is where web feeds come in handy, as they enable asynchronous data discovery. Importantly, notifications about updated feed content are not initiated by the server; instead, the client periodically retrieves the feeds. The server then returns the document, and the client compares the new content with existing data and adds the newly published content.
Web feeds are useful in various scenarios:
*News and Blogs:* A classic example is a news website where the owner wants to inform readers about the publication of new articles.
*Cloud Providers:* Operations teams can follow web feeds from cloud providers to be notified of changes to services, such as new features, deprecations, or outages.
*Cloud Providers:* * *Cybersecurity:* Cybersecurity companies can use web feeds to inform users about new threats or discovered vulnerabilities, allowing them to receive the latest updates and take action.
Various feed formats exist, such as Media RSS, JSON Feed, RSS, and Atom, with RSS and Atom being the most common sources.
RSS (Really Simple Syndication)
*Definition:* RSS is a type of web feed that provides updates about website content in a standardized XML format that can be read by both humans and computers.
*Evolution:* The RSS specification (XML 1.0 formatted) was published by Netscape in 1999.
*Structure:* An RSS feed contains a summary of the content (news or blog). It begins with a `rss` root element, which indicates the version of the specification. The `channel` element contains metadata about the feed. The required elements for the channel are `title`, `description`, `link`, and `language`. The actual content is provided in the `item` element.
*Legacy Technology:* RSS feeds are now considered **legacy technology**. The challenges that led to the development of new formats were the fragmentation of different RSS variants (0.90 to 2.0), validation difficulties, limited support from feed readers, and a lack of extensibility.
Atom
*Definition:* Atom is a web standard that includes the *Atom Syndication Format* (an XML-based language for web feeds) and the *Atom Publishing Protocol (AtomPub)* (an HTTP-based protocol for publishing and editing web resources).
*Successor:* Atom was developed as the successor to RSS to address its shortcomings. It allows for metadata extensibility, supports Unicode for internationalization, enables the integration of various content types (text, HTML, XML), and was standardized by the IETF in 2005 as an official web feed format (RFC 4287).
*Structure:* Atom is an XML 1.0-based syndication format.
*Features:* Atom feeds can be combined. The format allows for specifying an individual language for each entry.
Content Syndication
Syndication refers to the act of selling or making content available to other organizations so that it can be published or displayed in multiple locations to reach a wider audience. In the context of web feeds, web syndication refers to the process of distributing and aggregating web content (such as blog posts, podcasts, or videos) to other websites.
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