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How the WCF Syndication Object Model Maps to Atom and RSS

When developing a Windows Communication Foundation (WCF) syndication service, you create feeds and items using the following classes:

A SyndicationFeed can be serialized into any syndication format for which a formatter is defined. WCF ships with two formatters: Atom10FeedFormatter and Rss20FeedFormatter.

The object model around SyndicationFeed and SyndicationItem is aligned more closely with the Atom 1.0 specification than the RSS 2.0 specification. This is because Atom 1.0 is a more substantial specification that defines elements that are ambiguous or omitted from the RSS 2.0 specification. Because of this, many items in the WCF syndication object model have no direct representation in the RSS 2.0 specification. When serializing SyndicationFeed and SyndicationItem objects into RSS 2.0, WCF allows you to serialize Atom-specific data elements as namespace-qualified extension elements that conform to the Atom specification. You can control this with a parameter passed to the Rss20FeedFormatter constructor.

The code samples in this topic use one of two methods defined here to do the actual serialization.

SerializeFeed serializes a syndication feed.


public void SerializeFeed(SyndicationFeed feed)
{
    Atom10FeedFormatter atomFormatter = feed.GetAtom10Formatter();
    Rss20FeedFormatter rssFormatter = feed.GetRss20Formatter();

    XmlWriter atomWriter = XmlWriter.Create("atom.xml");
    XmlWriter rssWriter = XmlWriter.Create("rss.xml");
    atomFormatter.WriteTo(atomWriter);
    rssFormatter.WriteTo(rssWriter);
    atomWriter.Close();
    rssWriter.Close();
}


SerializeItem serializes a syndication item.


public void SerializeItem(SyndicationItem item)
{
    Atom10ItemFormatter atomFormatter = item.GetAtom10Formatter();
    Rss20ItemFormatter rssFormatter = item.GetRss20Formatter();

    XmlWriter atomWriter = XmlWriter.Create("atom.xml");
    XmlWriter rssWriter = XmlWriter.Create("rss.xml");
    atomFormatter.WriteTo(atomWriter);
    rssFormatter.WriteTo(rssWriter);
    atomWriter.Close();
    rssWriter.Close();
}


The following code example shows how to serialize the SyndicationFeed class to Atom 1.0 and RSS 2.0.


SyndicationFeed feed = new SyndicationFeed("My Feed Title", "My Feed Description", new Uri("http://MyFeedURI"));
feed.Copyright = new TextSyndicationContent("Copyright 2007");
feed.Language = "EN-US";
feed.LastUpdatedTime = DateTime.Now;
feed.Generator = "Sample Code";
feed.Id = "FeedID";
feed.ImageUrl = new Uri("http://server/image.jpg");

SyndicationCategory category = new SyndicationCategory("MyCategory");
category.Label = "categoryLabel";
category.Name = "categoryName";
category.Scheme = "categoryScheme";
feed.Categories.Add(category);

SyndicationItem item = new SyndicationItem("Item Title", "Item Content", new Uri("http://MyItemURI"));
item.Authors.Add(new SyndicationPerson("Jesper.Aaberg@contoso.com", "Jesper Aaberg", "http://Contoso/Aaberg"));
item.Categories.Add(category);
item.Contributors.Add(new SyndicationPerson("Lene.Aaling@contoso.com", "Lene Aaling", "http://Contoso/Aaling"));
item.Copyright = new TextSyndicationContent("Copyright 2007");
item.Id = "ItemID";
item.LastUpdatedTime = DateTime.Now;
item.PublishDate = DateTime.Today;
item.SourceFeed = feed;
item.Summary = new TextSyndicationContent("Item Summary");

Collection<SyndicationItem> items = new Collection<SyndicationItem>();
items.Add(item);
feed.Items = items;

SerializeFeed(feed);


The following XML shows how the SyndicationFeed is serialized to Atom 1.0.

<?xml version="1.0" encoding="utf-8"?>
<feed xml:lang="EN-US" xmlns="http://www.w3.org/2005/Atom">
  <title type="text">My Feed Title</title>
  <subtitle type="text">My Feed Description</subtitle>
  <id>FeedID</id>
  <rights type="text">Copyright 2007</rights>
  <updated>2007-08-29T13:57:17-07:00</updated>
  <category term="categoryName" label="categoryLabel" scheme="categoryScheme" />
  <logo>http://server/image.jpg</logo>
  <generator>Sample Code</generator>
  <link rel="alternate" href="http://myfeeduri/" />
  <entry>
    <id>ItemID</id>
    <title type="text">Item Title</title>
    <summary type="text">Item Summary</summary>
    <published>2007-08-29T00:00:00-07:00</published>
    <updated>2007-08-29T13:57:17-07:00</updated>
    <author>
      <name>Jesper Aaberg</name>
      <uri>http://Jesper/Aaberg</uri>
      <email>Jesper@Aaberg.com</email>
    </author>
    <contributor>
      <name>Lene Aaling</name>
      <uri>http://Lene/Aaling</uri>
      <email>Lene@Aaling.com</email>
    </contributor>
    <link rel="alternate" href="http://myitemuri/" />
    <category term="categoryName" label="categoryLabel" scheme="categoryScheme" />
    <content type="text">Item Content</content>
    <rights type="text">Copyright 2007</rights>
    <source>
      <title type="text">My Feed Title</title>
      <subtitle type="text">My Feed Description</subtitle>
      <id>FeedID</id>
      <rights type="text">Copyright 2007</rights>
      <updated>2007-08-29T13:57:17-07:00</updated>
      <category term="categoryName" label="categoryLabel" scheme="categoryScheme" />
      <logo>http://server/image.jpg</logo>
      <generator>Sample Code</generator>
      <link rel="alternate" href="http://myfeeduri/" />
    </source>
  </entry>
</feed>

The following XML shows how the SyndicationFeed is serialized to RSS 2.0.

<?xml version="1.0" encoding="utf-8"?>
<rss xmlns:a10="http://www.w3.org/2005/Atom" version="2.0">
  <channel>
    <title>My Feed Title</title>
    <link>http://myfeeduri/</link>
    <description>My Feed Description</description>
    <language>EN-US</language>
    <copyright>Copyright 2007</copyright>
    <lastBuildDate>Wed, 29 Aug 2007 13:57:17 -0700</lastBuildDate>
    <category domain="categoryScheme">categoryName</category>
    <generator>Sample Code</generator>
    <image>
      <url>http://server/image.jpg</url>
      <title>My Feed Title</title>
      <link>http://myfeeduri/</link>
    </image>
    <a10:id>FeedID</a10:id>
    <item>
      <guid isPermaLink="false">ItemID</guid>
      <link>http://myitemuri/</link>
      <author>Jesper@Aaberg.com</author>
      <category domain="categoryScheme">categoryName</category>
      <title>Item Title</title>
      <description>Item Summary</description>
      <source>My Feed Title</source>
      <pubDate>Wed, 29 Aug 2007 00:00:00 -0700</pubDate>
      <a10:updated>2007-08-29T13:57:17-07:00</a10:updated>
      <a10:rights type="text">Copyright 2007</a10:rights>
      <a10:content type="text">Item Content</a10:content>
      <a10:contributor>
        <a10:name>Lene Aaling</a10:name>
        <a10:uri>http://Lene/Aaling</a10:uri>
        <a10:email>Lene@Aaling.com</a10:email>
      </a10:contributor>
    </item>
  </channel>
</rss>

The following code example shows how to serialize the SyndicationItem class to Atom 1.0 and RSS 2.0.


SyndicationItem item = new SyndicationItem("Item Title", "Item Content", new Uri("http://MyItemURI"));
item.Authors.Add(new SyndicationPerson("Jesper.Aaberg@contoso.com", "Jesper Aaberg", "http://Contoso/Aaberg"));
item.Authors.Add(new SyndicationPerson("Syed.Abbas@contoso.com", "Syed Abbas", "http://Contoso/Abbas"));

SyndicationCategory category = new SyndicationCategory("MyCategory");
category.Label = "categoryLabel";
category.Name = "categoryName";
category.Scheme = "categoryScheme";

SyndicationCategory category2 = new SyndicationCategory("MyCategoryTwo");
category2.Label = "categoryLabel";
category2.Name = "categoryName";
category2.Scheme = "categoryScheme";

item.Categories.Add(category);
item.Categories.Add(category2);
item.Contributors.Add(new SyndicationPerson("Lene.Aaling@contoso.com", "Lene Aaling", "http://Contoso/Aaling"));
item.Contributors.Add(new SyndicationPerson("Kim.Abercrombie@contoso.com", "Kim Abercrombie", "http://Contoso/Abercrombie"));
item.Copyright = new TextSyndicationContent("Copyright 2007");
item.Id = "ItemID";
item.LastUpdatedTime = DateTime.Now;
item.PublishDate = DateTime.Today;
item.SourceFeed = feed;
item.Summary = new TextSyndicationContent("Item Summary");

Collection<SyndicationItem> items = new Collection<SyndicationItem>();
items.Add(item);
feed.Items = items;

SerializeItem(item);


The following XML shows how the SyndicationItem is serialized to Atom 1.0.

<entry xmlns="http://www.w3.org/2005/Atom">
  <id>ItemID</id>
  <title type="text">Item Title</title>
  <summary type="text">Item Summary</summary>
  <published>2007-08-29T00:00:00-07:00</published>
  <updated>2007-08-29T14:07:09-07:00</updated>
  <author>
    <name>Jesper Aaberg</name>
    <uri>http://Contoso/Aaberg</uri>
    <email>Jesper.Aaberg@contoso.com</email>
  </author>
  <author>
    <name>Syed Abbas</name>
    <uri>http://Contoso/Abbas</uri>
    <email>Syed.Abbas@contoso.com</email>
  </author>
  <contributor>
    <name>Lene Aaling</name>
    <uri>http://Contoso/Aaling</uri>
    <email>Lene.Aaling@contoso.com</email>
  </contributor>
  <contributor>
    <name>Kim Abercrombie</name>
    <uri>http://Contoso/Abercrombie</uri>
    <email>Kim.Abercrombie@contoso.com</email>
  </contributor>
  <link rel="alternate" href="http://myitemuri/" />
  <category term="categoryName" label="categoryLabel" scheme="categoryScheme" />
  <category term="categoryName" label="categoryLabel" scheme="categoryScheme" />
  <content type="text">Item Content</content>
  <rights type="text">Copyright 2007</rights>
  <source>
    <title type="text">My Feed Title</title>
    <subtitle type="text">My Feed Description</subtitle>
    <link rel="alternate" href="http://myfeeduri/" />
  </source>
</entry>

The following XML shows how the SyndicationItem is serialized to RSS 2.0.

<item>
  <guid isPermaLink="false">ItemID</guid>
  <link>http://myitemuri/</link>
  <author xmlns="http://www.w3.org/2005/Atom">
    <name>Jesper Aaberg</name>
    <uri>http://Jesper/Aaberg</uri>
    <email>Jesper@Aaberg.com</email>
  </author>
  <author xmlns="http://www.w3.org/2005/Atom">
    <name>Syed Abbas</name>
    <uri>http://Contoso/Abbas</uri>
    <email>Syed.Abbas@contoso.com</email>
  </author>
  <category domain="categoryScheme">categoryName</category>
  <category domain="categoryScheme">categoryName</category>
  <title>Item Title</title>
  <description>Item Summary</description>
  <source>My Feed Title</source>
  <pubDate>Wed, 29 Aug 2007 00:00:00 -0700</pubDate>
  <updated xmlns="http://www.w3.org/2005/Atom">2007-08-29T14:07:09-07:00</updated>
  <rights type="text" xmlns="http://www.w3.org/2005/Atom">Copyright 2007</rights>
  <content type="text" xmlns="http://www.w3.org/2005/Atom">Item Content</content>
  <contributor xmlns="http://www.w3.org/2005/Atom">
    <name>Lene Aaling</name>
    <uri>http://Contoso/Aaling</uri>
    <email>Lene.Aaling@contoso.com</email>
  </contributor>
  <contributor xmlns="http://www.w3.org/2005/Atom">
    <name>Kim Abercrombie</name>
    <uri>http://Contoso/Abercrombie</uri>
    <email>Kim.Abercrombie@contoso.com</email>
  </contributor>
</item>

The following code example shows how to serialize the SyndicationPerson class to Atom 1.0 and RSS 2.0.


SyndicationFeed feed = new SyndicationFeed("My Feed Title", "My Feed Description", new Uri("http://MyFeedURI"));
feed.Authors.Add(new SyndicationPerson("Jesper.Aaberg@contoso.com", "Jesper Aaberg", "http://Contoso/Aaberg"));
feed.Authors.Add(new SyndicationPerson("Syed.Abbas@contoso.com", "Syed Abbas", "http://Contoso/Abbas"));

feed.Contributors.Add(new SyndicationPerson("Lene.Aaling@contoso.com", "Lene Aaling", "http://Contoso/Aaling"));
feed.Contributors.Add(new SyndicationPerson("Kim.Abercrombie@contoso.com", "Kim Abercrombie", "http://Contoso/Abercrombie"));

SerializeFeed(feed);


The following XML shows how the SyndicationPerson is serialized to Atom 1.0.

  <author>
    <name>Jesper Aaberg</name>
    <uri>http://Contoso/Aaberg</uri>
    <email>Jesper.Aaberg@contoso.com</email>
  </author>
<contributor>
    <name>Lene Aaling</name>
    <uri>http://Contoso/Aaling</uri>
    <email>Lene.Aaling@contoso.com</email>
  </contributor>

The following XML shows how the SyndicationPerson class is serialized to RSS 2.0 if only one SyndicationPerson exists in the Authors or Contributors collections, respectively.

<author>Jesper.Aaberg@contoso.com</author>
<a10:contributor>
    <a10:name>Lene Aaling</a10:name>
    <a10:uri>http://Contoso/Aaling</a10:uri>
    <a10:email>Lene.Aaling@contoso.com</a10:email>
</a10:contributor>

The following XML shows how the SyndicationPerson class is serialized to RSS 2.0 if more than one SyndicationPerson exists in the Authors or Contributors collections, respectively.

<a10:author>
    <a10:name>Jesper Aaberg</a10:name>
    <a10:uri>http://Contoso/Aaberg</a10:uri>
    <a10:email>Jesper.Aaberg@contoso.com</a10:email>
</a10:author>
<a10:author>
    <a10:name>Syed Abbas</a10:name>
    <a10:uri>http://Contoso/Abbas</a10:uri>
    <a10:email>Syed.Abbas@contoso.com</a10:email>
</a10:author>
<a10:contributor>
    <a10:name>Lene Aaling</a10:name>
    <a10:uri>http://Contoso/Aaling</a10:uri>
    <a10:email>Lene.Aaling@contoso.com</a10:email>
</a10:contributor>
<a10:contributor>
    <a10:name>Kim Abercrombie</a10:name>
    <a10:uri>http://Contoso/Abercrombie</a10:uri>
    <a10:email>Kim.Abercrombie@contoso.com</a10:email>
</a10:contributor>

The following code example shows how to serialize the SyndicationLink class to Atom 1.0 and RSS 2.0.


SyndicationFeed feed = new SyndicationFeed("My Feed Title", "My Feed Description", new Uri("http://MyFeedURI"));
feed.Links.Add(new SyndicationLink(new Uri("http://contoso/MyLink"), "alternate", "My Link Title", "text/html", 2048));

SerializeFeed(feed);


The following XML shows how the SyndicationLink is serialized to Atom 1.0.

<link rel="alternate" type="text/html" title="My Link Title" length="2048" href="http://contoso/MyLink" />

The following XML shows how the SyndicationLink is serialized to RSS 2.0.

<a10:link rel="alternate" type="text/html" title="My Link Title" length="2048" href="http://contoso/MyLink" />

The following code example shows how to serialize the SyndicationCategory class to Atom 1.0 and RSS 2.0.


SyndicationFeed feed = new SyndicationFeed("My Feed Title", "My Feed Description", new Uri("http://MyFeedURI"));

SyndicationCategory category = new SyndicationCategory("MyCategory");
category.Label = "categoryLabel";
category.Name = "categoryName";
category.Scheme = "categoryScheme";
feed.Categories.Add(category);

SerializeFeed(feed);


The following XML shows how the SyndicationCategory is serialized to Atom 1.0.

<category term="categoryName" label="categoryLabel" scheme="categoryScheme" />

The following XML shows how the SyndicationCategory is serialized to RSS 2.0.

<category domain="categoryScheme">categoryName</category>

The following code example shows how to serialize the TextSyndicationContent class to Atom 1.0 and RSS 2.0 when TextSyndicationContent is created with HTML content.


SyndicationItem htmlItem = new SyndicationItem();
htmlItem.Content = new TextSyndicationContent("<html> some html </html>", TextSyndicationContentKind.Html);

SerializeItem(htmlItem);


The following XML shows how the TextSyndicationContent class with HTML content is serialized to Atom 1.0.

<content type="html">&lt;html&gt; some html &lt;/html&gt;</content>

The following XML shows how the TextSyndicationContent class with HTML content is serialized to RSS 2.0.

<description>&lt;html&gt; some html &lt;/html&gt;</description>

The following code example shows how to serialize the TextSyndicationContent class to Atom 1.0 and RSS 2.0 when TextSyndicationContent is created with plain text content.


SyndicationItem txtItem = new SyndicationItem();
txtItem.Content = new TextSyndicationContent("Some Plain Text", TextSyndicationContentKind.Plaintext);

SerializeItem(txtItem);


The following XML shows how the TextSyndicationContent class with plain text content is serialized to Atom 1.0.

<content type="text">Some Plain Text</content>

The following XML shows how the TextSyndicationContent class with plain text content is serialized to RSS 2.0.

<description>Some Plain Text</description>

The following code example shows how to serialize the TextSyndicationContent class to Atom 1.0 and RSS 2.0 when TextSyndicationContent is created with XHTML content.


SyndicationItem xhtmlItem = new SyndicationItem();
xhtmlItem.Content = new TextSyndicationContent("<html> some xhtml </html>", TextSyndicationContentKind.XHtml);

SerializeItem(xhtmlItem);


The following XML shows how the TextSyndicationContent class with XHTML content is serialized to Atom 1.0.

<content type="xhtml">

<html> some xhtml </html>

</content>

The following XML shows how the TextSyndicationContent class with XHTML content is serialized to RSS 2.0.

<description>&lt;html&gt; some xhtml &lt;/html&gt;</description>

The following code example shows how to serialize the UrlSyndicationContent class to Atom 1.0 and RSS 2.0.


SyndicationItem urlItem = new SyndicationItem();
urlItem.Content = new UrlSyndicationContent(new Uri("http://Contoso/someUrl"), "audio");

SerializeItem(urlItem);


The following XML shows how the UrlSyndicationContent class is serialized to Atom 1.0.

<content type="audio" src="http://someurl/" />

The following XML shows how the UrlSyndicationContent class with XHTML content is serialized to RSS 2.0.

<description />

<content type="audio" src="http://Contoso/someurl/" xmlns="http://www.w3.org/2005/Atom" />

The following code example shows how to serialize the XmlSyndicationContent class to Atom 1.0 and RSS 2.0.


SyndicationItem xmlItem = new SyndicationItem();

xmlItem.Title = new TextSyndicationContent("Xml Item Title");
xmlItem.Content = new XmlSyndicationContent("mytype", new SyndicationElementExtension(new SomeData()));

SerializeItem(xmlItem);


The following XML shows how the XmlSyndicationContent class is serialized to Atom 1.0.

<content type="mytype">

<SomeData xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://schemas.datacontract.org/2004/07/FeedMapping" />

</content>

The following XML shows how the XmlSyndicationContent class with XHTML content is serialized to RSS 2.0.

<content type="mytype" xmlns="http://www.w3.org/2005/Atom">

<SomeData xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://schemas.datacontract.org/2004/07/FeedMapping" />

</content>

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