generating syndication feeds

Generating syndication feeds and other syndicated content

All of the framework API classes that represent syndication resources (RSS feeds, Atom feeds and entry documents, OPML documents, etc.) expose an overloaded Save method that allows you to persist a syndication resource. While the framework is flexible enough to load syndication resources that may not conform to their syndication specification, the framework will +always+ generate XML output that conforms strictly to the appropriate syndication specification. This "load flexibly, write strictly" methodology ensures you can consume syndication resources with confidence while still knowing that you will be publishing syndicated content that is standards based.

Example #1: Writing syndicated content

The simplest way to persist a syndication resource (e.g. feed) is to pass a Stream to the Save method that all framework syndication resources expose. If you want to have more control over the XML formatting of the persisted data, you can pass an XmlWriter as the argument to the Save method instead. When passing a Stream as the argument to the Save method, the framework uses the default SyndicationResourceSaveSettings class properties to determine the indenting and character encoding of the XmlWriter that is constructed against the supplied stream.

How to save an RSS feed

using System.IO;
using Argotic.Syndication;

RssFeed feed = new RssFeed();

feed.Channel.Link = new Uri("http://localhost");
feed.Channel.Title = "Simple RSS Feed";
feed.Channel.Description = "A minimal RSS 2.0 syndication feed.";

RssItem item = new RssItem();
item.Title = "Simple RSS Item";
item.Link = new Uri("http://localhost/items/SimpleRSSItem.aspx");
item.Description = "A minimal RSS channel item.";

feed.Channel.AddItem(item);

using(FileStream stream = new FileStream("SimpleRssFeed.xml", FileMode.Create, FileAccess.Write))
{
    feed.Save(stream);
}

The RSS feed generated in the above example represents the minimal information required per the RSS 2.0 specification.

How to save an Atom feed

using System.IO;
using Argotic.Syndication;

AtomFeed feed = new AtomFeed();

feed.Id = new AtomId(new Uri("http://localhost"));
feed.Title = new AtomTextConstruct("Simple Atom Feed");
feed.UpdatedOn = DateTime.Now;

feed.Authors.Add(new AtomPersonConstruct("Brian William Kuhn"));

AtomLink selfLink = new AtomLink();
selfLink.Relation = "self";
selfLink.Uri = new Uri("http://localhost/atom.xml");
feed.Links.Add(selfLink);

AtomEntry entry = new AtomEntry();
entry.Id = new AtomId(new Uri("urn:uuid:fbd850a0-e333-12dc-bc36-7d8b00dd6d4c"));
entry.Title = new AtomTextConstruct("Simple Atom Entry");
entry.UpdatedOn = DateTime.Now;
entry.Summary = new AtomTextConstruct("A minimal Atom feed entry.");

AtomLink alternateLink = new AtomLink();
alternateLink.Relation = "alternate";
alternateLink.Uri = new Uri("http://localhost/entries/SimpleAtomEntry.aspx");
entry.Links.Add(alternateLink);

feed.AddEntry(entry);

using (FileStream stream = new FileStream("SimpleAtomFeed.xml", FileMode.Create, FileAccess.Write))
{
    feed.Save(stream);
}

The Atom feed generated in the above example represents the minimal information required per the Atom 1.0 specification.

How to save an Atom entry document

using System.IO;
using Argotic.Syndication;

AtomEntry entry = new AtomEntry();

entry.Id = new AtomId(new Uri("http://localhost"));
entry.Title = new AtomTextConstruct("Atom Entry Document");
entry.UpdatedOn = DateTime.Now;
entry.Authors.Add(new AtomPersonConstruct("Brian William Kuhn"));
entry.Summary = new AtomTextConstruct("A stand-alone Atom Entry Document.");

AtomLink alternateLink = new AtomLink();
alternateLink.Relation = "alternate";
alternateLink.Uri = new Uri("http://localhost/entries/SimpleAtomEntry.aspx");
entry.Links.Add(alternateLink);

using (FileStream stream = new FileStream("AtomEntryDocument.xml", FileMode.Create, FileAccess.Write))
{
    entry.Save(stream);
}

The Atom entry document generated in the above example represents the minimal information required per the Atom 1.0 specification.

Example #2: Specifying the set of features to support when generating syndicated content

The framework provides a means of specifying the set of features that are supported when persisting a syndication resource via the SyndicationResourceSaveSettings class. This class is passed as an argument to the Save method of the syndication resource in order to configure how the save operation is performed.

The SyndicationResourceSaveSettings class exposes the following properties:

• AutoDetectExtensions - Indicates if syndication extensions supported by the save operation are automatically determined based on the syndication extensions added to the syndication resource and its child entities.
• CharacterEncoding - Indicates the character encoding that is used when persisting a syndication resource.
• MinimizeOutputSize - Indictaes if syndication resource persist operations should attempt to minimize the physical size of the resulting output.
• SupportedExtensions - Indicates the custom syndication extensions that you wish the save operation to support.

How to save an RSS feed with a smaller total file size

using System.IO;
using Argotic.Common;
using Argotic.Syndication;

RssFeed feed = new RssFeed();

feed.Channel.Link = new Uri("http://localhost");
feed.Channel.Title = "Compact RSS Feed";
feed.Channel.Description = "A minimal and non-indented RSS 2.0 syndication feed.";
    
RssItem item = new RssItem();
item.Title = "Simple RSS Item";
item.Link = new Uri("http://localhost/items/SimpleRSSItem.aspx");
item.Description = "A minimal RSS channel item.";
    
feed.Channel.AddItem(item);

using (FileStream stream = new FileStream("CompactRssFeed.xml", FileMode.Create, FileAccess.Write))
{
    SyndicationResourceSaveSettings settings = new SyndicationResourceSaveSettings();
    settings.MinimizeOutputSize = true;

    feed.Save(stream, settings);
}