OfficeIMO.Opml 3.4.2

OfficeIMO.Opml

OfficeIMO.Opml creates, reads, edits, validates, converts, and writes OPML 1.0 and 2.0 documents without a third-party parser. A declared OPML 1.1 document is read using the 1.0 profile, as specified by OPML 2.0.

Install

dotnet add package OfficeIMO.Opml

using OfficeIMO.Opml;

OpmlDocument document = OpmlDocument.Create(OpmlVersion.Opml20);
document.Head.Title = "Subscriptions";

OpmlOutline folder = document.AddOutline("Technology");
OpmlOutline feed = folder.AddChild("OfficeIMO");
feed.Type = "rss";
feed.XmlUrl = "https://example.com/feed.xml";
feed.HtmlUrl = "https://example.com/";

document.Validate();
document.Save("subscriptions.opml");

Standard subscription attributes are typed, while GetAttribute and SetAttribute accept XName for namespaced extensions. Unknown attributes, elements, comments, processing instructions, and namespace declarations remain in the backing XDocument. An unchanged file or stream is written byte-for-byte; after an edit, preserved XML is serialized around the changed values.

ToOfficeDocumentModel() and FromOfficeDocumentModel() map nested outlines through OfficeDocumentModel.Structure; subscription and outline URLs are also published through OfficeDocumentModel.Links. Independent flat blocks or links are appended as top-level outlines when recursive structure does not already represent them, with a placement-loss diagnostic. Tables, assets, pages, forms, and structured visuals have no OPML outline equivalent, so reverse conversion omits each populated item with a loss diagnostic. Both conversion directions enforce OpmlConversionOptions.MaxStructureDepth and MaxStructureNodes; reverse conversion also rejects cyclic structures. Conversion results implement IOfficeConversionReport, so callers can inspect diagnostics or call RequireNoLoss().

Safety and profile limits

• XML DTDs and external entity resolution are disabled.
• Default limits are 16 MiB encoded input, 16 million XML characters, 128 levels, 250,000 total elements, 100,000 outlines, and 500,000 attributes. Override them with OpmlReadOptions.
• Validation covers the OPML root/head/body contract, declared version, required text, RSS xmlUrl, and link/include url.
• Validation and conversion retain at most 100 detailed diagnostics per code by default, followed by one occurrence summary. Override the budget with OpmlValidationOptions or OpmlConversionOptions.
• Reader integration is provided by OfficeIMO.Reader.Opml.

The implemented vocabulary follows the OPML 2.0 specification. Targets: netstandard2.0, net8.0, net10.0, and net472 on Windows.

Dependency footprint

• External: None.
• OfficeIMO: OfficeIMO.Core.

See the complete OfficeIMO package map for related formats and conversion paths.