An example of XML dialect: Content syndication¶

Introduction¶

The syndication (or broadcasting) of web content is that a part of the content of a web page is made available to other sites or individual subscribers through a web channel, the most common used format is RSS, followed by the Atom. Computer programs that comply with any of these standards they periodically consult a file with several entries linking to the full or partial articles on the original website. Unlike other media, web content broadcast rights are usually free, and do not usually intervene a contract between the parties but a licence rules.

A little history¶

As a web user, it is very important to get links from websites that interest you and store them. In such a way that you are able to get back to them quickly. If you wanted to follow the changes on the web pages the only way to do that it was to visit the website to check for news.

The advent of what became known as Web 2.0 complicated things. The Web was filled with a large number of blogs and pages that published information, and visiting them all to see if there were any changes took a long time, and, in addition, it is very likely that pages have not changed.

The advent of standard syndication systems made possible to obtain information updates a website in a stable way through an specific address. Content syndication changed the way the content is retrieved. You no longer had to look for information: it was the information that went to the user.

By using syndication, user no longer needs to visit the pages that interest him to see if there are any changes, because if there are any you will already receive them. This leads to savings of time, as you will not have to visit pages to discover that there are no changes.

Another advantage that syndication brings is inherent in XML. Unlike of what happens with HTML, it is easy to interpret the content of the information that is received and therefore it will also be easy to be able to reuse the content to make others tasks.

Although syndication is often seen as a system focused on detecting updates on the Web, it is also being used to keep updates in other fields. For example, some computer programs use RSS to find out if there are new versions or updates and thus keep the programs up to date.

Content syndication today¶

At present, with the emergence of social networks and other technologies, the use of content syndication with standard formats has decreased and the content broadcasting has focused on posting on social media and the use of other sharing systems such as APIs.

However, in the world of podcast, it continues to be used as an automatic way to share content.

Example of use¶

Using a podcatcher we can download the new podcasts published.

Adding the feed (name given to the list of items) shows us what's new that there is.

Once added, we are subscribed and the podcatcher will notify us of news.

Structure of content channels¶

Web feeds allow programs to check if there are updates posted on a website. To provide a web channel, the site owner may use specialized software (such as a content management system) that publishes a list (or "feed") of articles or recent content in a standardized automatic reading format.

The channel can be downloaded through programs that use it, such as websites that distribute feed content, or through feed readers called aggregators that allow Internet users to subscribe to channels and view their content.

A channel (feed) contains entries, which can be headlines, full-text articles, extracts, summaries, or links to content from a website along with various metadata.

Next we will analyse the characteristics of the two standards, based on XML, for creating content channels: RSS 2.0 and Atom 1.0.

RSS 2.0¶

RSS (RDF Site Summary or Really Simple Syndication) is a web feed (or feed) that allows users and applications access website updates in a format standardized and computer readable.

It was developed by the RSS Advisory Board and its first version, RSS 0.90, appeared in March 1999. The latest version, 2.0, was released in March 2009.

RSS is an XML dialect. The RSS format itself is relatively easy to read for both automated and human processes. An example feed can have content as follows:

<?xml version="1.0" encoding="UTF-8"?>
<rss version="2.0">
<channel>
 <title>RSS Title</title>
 <description> This is an example of an RSS feed</description>
 <link>http://www.example.com/main.html</link>
 <copyright>2020 Example.com All rights reserved</copyright>
 <lastBuildDate>Mon, 06 Sep 2010 00:01:00 +0000</lastBuildDate>
 <pubDate>Sun, 06 Sep 2009 16:20:00 +0000</pubDate>
 <ttl>1800</ttl>

 <item>
  <title>Example entry</title>
  <description>Here is some text containing an interesting 
    description.</description>
  <link> http://www.example.com/blog/post/1</link>
  <guid isPermaLink = "false">7bd204c6-1655-4c27-aeee-53f933c5395f</guid>
  <pubDate>Sun, 06 Sep 2009 16:20:00 +0000</pubDate>
 </item>
</channel>
</rss>

RSS feed tree diagram

At the top level, an RSS document is a <rss> element, with an attribute required called version, which specifies the RSS version it meets the document.

Subordinate to the <rss> element is a <channel> element that contains information about the channel (metadata) and its content in <item> elements.

Despite the fact that there is not an official RSS schema, we can find some implementations like this: RSS 2.0.

Atom¶

The atom syndication format is an XML dialect used for web feeds.

The Atom format was developed as an alternative to RSS. Ben Trott, defender of the new format that became Atom, believed that RSS had limitations and flaws, such as the lack of continuous innovation and its need to remain compatible, and that there were advantages in a new design.

A document based on the Atom format has the following structure:

<?xml version="1.0" encoding = "utf-8"?>

<feed xmlns = "http://www.w3.org/2005/Atom">
  <title> Example Feed </title>
  <subtitle> A subtitle. </subtitle>
  <link href = "http://example.org/feed/" rel = "self" />
  <link href = "http://example.org/" />
  <id> urn: uuid: 60a76c80-d399-11d9-b91C-0003939e0af6 </id>
  <updated> 2003-12-13T18: 30: 02Z </updated>


<entry>
  <title> Atom-Powered Robots Run Amok </title>
  <link href = "http://example.org/2003/12/13/atom03" />
  <link rel = "alternate" type = "text / html"
    href = "http://example.org/2003/12/13/atom03.html" />
  <link rel = "edit" href = "http://example.org/2003/12/13/atom03/edit" />
  <id> urn: uuid: 1225c695-cfb8-4ebb-aaaa-80da344efa6a </id>
  <updated> 2003-12-13T18: 30: 02Z </updated>
  <summary> Some text. </summary>
    <content type = "xhtml">
      <div xmlns = "http://www.w3.org/1999/xhtml">
        <p> This is the entry content. </p>
      </div>
    </content>
    <author>
      <name> John Doe </name>
      <email> johndoe@example.com </email>
    </author>
</entry>

</feed>

For more details: RFC 4287 - The Atom Syndication Format

Although it is possible to use XML validators, the most common is to do so serve specific programs to validate RSS and Atom such as the W3C Feed Validation Service (validator.w3.org/feed)

Credits, bibliography and webography¶

• Col·laboradors de la Viquipèdia. Redifusió de continguts web [en línia]. Viquipèdia, l'Enciclopèdia Lliure, 2019 [data de consulta: 15 de novembre del 2019]. Disponible en .

• Xavier Sala. Sindicació de continguts available at https://ioc.xtec.cat/materials/FP/Recursos/fp_asx_m04_/web/fp_asx_m04_htmlindex/WebContent/u3/a1/continguts.html.