The Basics of RSS Feeds and their growing popularity:
RSS is an increasingly popular format for delivering content such as broadcasts, blogs, news, syndications, and metadata over the Internet. This simple, XML-based method of content publishing allows users the ability to subscribe to various forms information. Most commonly, RSS Feeds are used throughout many web communities for sharing topical information such as linking to headline news articles and sharing user comments (up-to-date posts) within blog groups.
Subscribing to an RSS Feed allows for the integration of outside or third-party content into one's own website or blog forum without actually having to host the content themselves nor provide the means for streaming it in order to access and share with others. In this type of RSS delivery, users simply click on the provided RSS Feed links and then access the data or information, which actually resides (and is hosted by) the original publisher of the content.
RSS Feeds are also becoming a popular way of providing information related to online shopping and services. Companies that deal in e-commerce and online product promotion are using RSS Feeds to advertise, cross-promote, and expose their goods or services across a much broader audience spectrum. Amazon.Com for example, provides a web service that allows users to keep track of their favorite or best selling books through RSS Feed subscriptions. This Feed can then be placed upon the customer's website or delivered to a preferred newsreader as a means of accessing and exposing the product to others at any given time.
Various definitions are used to describe the RSS acronym, depending on which version is being referred to. Currently, the accepted definition for RSS (version 2.0) stands for "Really Simple Syndication". Earlier versions carry a slightly different definition such as the RSS (versions 0.91 & 1.0), often called "Rich Site Summary". Basically, RSS is family of web formats (specified in XML) that are used to provide users with frequently updated information and/or multimedia rich material through subscriptions to RSS web feeds. The publishers of the material distribute their content to their RSS Feeder, which delivers the data as an XML file to the subscribers. The subscribers are then able to access the media by using a Feed Reader (a.k.a. an aggregator program) that runs locally on their system.
An aggregator program provides a quick and almost effortless means of regularly checking a website for updates through user subscriptions to RSS Feeders. Subscribing to a feed gives the aggregator the ability to periodically search for new content (search intervals set by user preference) and retrieve it as it becomes updated or when new information becomes available. XML Aggregator programs can be found in portal sites such as My Yahoo!, Google, modern web browsers, e-mail applications, Apple iTunes, mobile phones and Tivo recording systems.
The RSS Structure:
RSS files are made up of "Channel" elements ( <channel> - open/closed braces swaped for purpose of HTML display) and their sub-elements. The RSS <channel> contains elements that represent metadata about the channel's items such as Title ( <title>) , Link ( <link> ), and Description ( <description> ). These items typically make up the bulk of the channel element, and contain dynamic content that frequently changes.
A channel usually has three elements that describe the channel itself:
- <title> - The name of the channel or webfeed
- <link> - The URL of the Web site providing this channel
- <description> - A brief summary of what the channel content is
Channel sub-elements are optional in the RSS Structure but there are some that are commonly used such as the "Image" element ( <image> - open/closed braces swaped for purpose of HTML display), which contains three required sub-elements in order to be used:
- <url> - The URL of a GIF, JPEG, or PNG image that represents the channel identity
- <title> - Describes the image. It is used in the ALT attribute of the HTML <image> tag when the channel is rendered in HTML
- <link> - The URL of the site. When the channel is rendered as HTML, the image can act as a link to the site.
Optional <image> elements
"Image" ( <image> ) also has three optional items or sub-elements:
- <width> - Number indicating the width of the image in pixels.
- <height> - Number indicating the height of the image in pixels.
- <description> - Contains text that is included in the "title" attribute of the link that's formed upon image rendering
Other Optional Channels ( <channel> )
Addition options are available for use within channel elements such as those shown below.
- <language> - en-us
- <copyright> - Copyright 2003, James Lewin
- <managingEditor> - contact_me.com (Editor's Name)
- <webmaster> - contact_me.com (Web Master's Name)
- <pubDate> - Sun, 25 Dec 2004 0:00:00 EST
- <lastBuildDate> - Sun, 25 Dec 2004 0:00:00 EST
- <category> - ecommerce
- <generator> - a CMS
- <docs> - http://aii.edu/docs/rss
- <cloud> - Allows processes to register with a "cloud" to be notified of updates to the channel, implementing a lightweight publish-subscribe protocol for RSS feeds
- <ttl> - "Time to live", a number representing the minutes a feed can be cached before it should be refreshed.
- <rating> - Rating for the channel
- <textInput> - Defines an input box that can be displayed along with the channel
- <skipHours> - A hint for aggregators that tells them which hours can be skipped for updating
- <skipDays> - A hint for aggregators that tells them which days can be skipped for updating
The most important part of a web feeds are the items within them, often blog entries, complete articles, movie reviews, classified ads, audio & video syndications, etc. Items are sub-elements that change frequently while other elements of a channel ( <channel> ) stay constant.
Elements of news items
"Items" typically contains three elements:
- <title> - This is the name of the item which is translated into a headline within the HTML
- <link> - The URL of the item. The title is commonly used as a link, pointing to the URL contained within the <link> element
- <description> - This is usually a summary about the URL that is pointed to in the link
All other elements are optional, but an item must contain either a <title> or <description> tag.
Other optional elements of items that can be used are:
- <author> - E-mail address of the author
- <category> - Supports organizing entries
- <comments> - URL of a page for comments on the item
- <enclosure> - Supports media objects associated with the item
- <guide> - A permanent link that is uniquely tied to the item
- <pubDate> - When the item was published
- <source> - The RSS channel that an item comes from. This can be useful when items are aggregated together
Below is an example of a simple RSS Feed: