Parsing OPML Files with the RSS Component

OPML (Outline Processor Markup Language) is an XML format for outlines. It is commonly used to export and import lists of feed subscriptions (e.g., from feed readers and podcast applications), where each outline entry contains the URL of an RSS or Atom feed.

The RSS component can parse OPML files using the ReadOPML method. When it is called, the component parses the file, and fires the OPMLHeader event for each field in the header of the document (e.g., title or dateCreated), followed by the OPMLOutline event for each outline entry.

RSS rss = new RSS();

rss.OnOPMLHeader += (s, e) =>
{
  Console.WriteLine(e.Field + ": " + e.Value);
};

rss.OnOPMLOutline += (s, e) =>
{
  // Level is the depth of the entry in the outline, which can be used to show the hierarchy of the document.
  string indent = new string(' ', e.Level * 2);
  Console.WriteLine(indent + e.Text + (e.XMLURL.Length > 0 ? " (" + e.XMLURL + ")" : ""));
};

rss.ReadOPML("C:\\feeds\\subscriptions.opml");

The OPMLOutline event provides the common attributes of each outline entry as parameters:

The value of any other attribute can be retrieved by calling the OPMLAttr method with the name of the attribute inside the OPMLOutline event.

Reading OPML Files from a URL

The ReadOPML method reads a local file. To parse an OPML file from a web server, first download it to a local file using the HTTP component, and then pass the path of the file to ReadOPML.

HTTP http = new HTTP();
http.LocalFile = Path.Combine(Path.GetTempPath(), "subscriptions.opml");
http.Get("https://www.example.com/subscriptions.opml");

rss.ReadOPML(http.LocalFile);

Each feed found in the document can then be retrieved with the GetFeed method of the RSS component, using the URL in the XMLURL parameter.