RSS-版本历史

什么是RSS?

RSS(Rich Site Summary 或 Really Simple Syndication)是一种用于在线发布和订阅更新内容的标准格式。使用RSS可以将更新内容通过RSS阅读器传输到订阅者的设备上，并能够实时更新内容。

RSS的版本历史

RSS 0.90

最早的RSS版本是 RSS 0.90，由Netscape公司于1999年创建。此版本由RDF格式组成，它本身是一种简单的、类XML的元数据语言，可用于描述万维网资源。

<rss version="0.90">
  <channel>
    <title>Liftoff News</title>
    <link>http://liftoff.msfc.nasa.gov/</link>
    <description>Liftoff to Space Exploration.</description>
    <language>en-us</language>
    <pubDate>Tue, 10 Jun 2003 04:00:00 GMT</pubDate>
    <lastBuildDate>Tue, 10 Jun 2003 09:41:01 GMT</lastBuildDate>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <generator>Weblog Editor 2.0</generator>
    <managingEditor>editor@example.com</managingEditor>
    <webMaster>webmaster@example.com</webMaster>
    <item>
      <title>Star City</title>
      <link>
        http://liftoff.msfc.nasa.gov/news/2003/news-starcity.asp
      </link>
      <description>How do Americans get ready to work with Russians aboard the International Space Station? They take a crash course in culture, language and protocol at Russia's Star City.</description>
      <pubDate>Tue, 03 Jun 2003 09:39:21 GMT</pubDate>
      <guid>
        http://liftoff.msfc.nasa.gov/2003/06/03.html#item573
      </guid>
    </item>
  </channel>
</rss>

RSS 0.91

RSS 0.91 于2000年发布，是对0.90版本的一次小改进，主要添加了“cloud”元素和“category”元素。该版本没有使用XML命名空间。

<rss version="0.91">
  <channel>
    <title>Liftoff News</title>
    <link>http://liftoff.msfc.nasa.gov/</link>
    <description>Liftoff to Space Exploration.</description>
    <lastBuildDate>Tue, 10 Jun 2003 09:41:01 GMT</lastBuildDate>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <cloud domain='rpc.sys.com' port='80' path='/RPC2' registerProcedure='pingMe' protocol='soap'/>
    <category domain="http://sys.com/category">sometopic</category>
    <item>
      <title>Star City</title>
      <link>
        http://liftoff.msfc.nasa.gov/news/2003/news-starcity.asp
      </link>
      <description>How do Americans get ready to work with Russians aboard the International Space Station? They take a crash course in culture, language and protocol at Russia's Star City.</description>
    </item>
  </channel>
</rss>

RSS 0.92

在2001年，RSS 0.92发布，主要是通过添加XML命名空间清理了元素的混乱。该版本增加了“image”元素。

<rss version="0.92" xmlns:image="http://imagens.com/">
  <channel>
    <title>Liftoff News</title>
    <link>http://liftoff.msfc.nasa.gov/</link>
    <description>Liftoff to Space Exploration.</description>
    <language>en-us</language>
    <image>
        <url>http://liftoff.msfc.nasa.gov/gallery/images/</url>
        <title>Liftoff News</title>
        <link>http://liftoff.msfc.nasa.gov/</link>
    </image>
    <item>
      <title>Star City</title>
      <link>
        http://liftoff.msfc.nasa.gov/news/2003/news-starcity.asp
      </link>
      <description>How do Americans get ready to work with Russians aboard the International Space Station? They take a crash course in culture, language and protocol at Russia's Star City.</description>
    </item>
  </channel>
</rss>

RSS 1.0

RSS 1.0于2000年发布，是RDF Site Summary标准的扩展。 它基于RDF，并使用XML命名空间。该版本使用“rdf:about”属性作为项目标识符。

<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
         xmlns="http://purl.org/rss/1.0/">
  <channel rdf:about="http://liftoff.msfc.nasa.gov/">
    <title>Liftoff News</title>
    <link>http://liftoff.msfc.nasa.gov/home.htm</link>
    <description>Liftoff to Space Exploration.</description>
    <items>
      <rdf:Seq>
        <rdf:li rdf:resource="http://liftoff.msfc.nasa.gov/news/2003/news-starcity.asp"/>
      </rdf:Seq>
    </items>
  </channel>
  <item rdf:about="http://liftoff.msfc.nasa.gov/news/2003/news-starcity.asp">
    <title>Star City</title>
    <link>http://liftoff.msfc.nasa.gov/news/2003/news-starcity.asp</link>
    <description>How do Americans get ready to work with Russians aboard the International Space Station? They take a crash course in culture, language and protocol at Russia's Star City. </description>
  </item>
</rdf:RDF>

RSS 2.0

于2002年发布的RSS 2.0是目前最常用的版本。它仍然使用XML命名空间，并添加了“enclosure”元素和“GUID”元素。

<rss version="2.0">
  <channel>
    <title>Liftoff News</title>
    <link>http://liftoff.msfc.nasa.gov/</link>
    <description>Liftoff to Space Exploration.</description>
    <language>en-us</language>
    <pubDate>Tue, 10 Jun 2003 04:00:00 GMT</pubDate>
    <lastBuildDate>Tue, 10 Jun 2003 09:41:01 GMT</lastBuildDate>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <generator>Weblog Editor 2.0</generator>
    <managingEditor>editor@example.com</managingEditor>
    <webMaster>webmaster@example.com</webMaster>
    <item>
      <title>Star City</title>
      <link>
        http://liftoff.msfc.nasa.gov/news/2003/news-starcity.asp
      </link>
      <description>How do Americans get ready to work with Russians aboard the International Space Station? They take a crash course in culture, language and protocol at Russia's Star City.</description>
      <pubDate>Tue, 03 Jun 2003 09:39:21 GMT</pubDate>
      <guid isPermaLink="false">http://liftoff.msfc.nasa.gov/2003/06/03.html#item573</guid>
      <enclosure url="http://liftoff.msfc.nasa.gov/2003/06/03.html#item573"
                 length="123456"
                 type="audio/mpeg" />
    </item>
  </channel>
</rss>

总体来说，RSS在不断地演变和改进，它在内容的领域内已经成为了一个非常重要的标准。