Atom

Feed.Atom takes feed metadata and an entries list. It enforces id, title, and updated on the feed and each entry. Other validation rules in RFC 4287 remain the application's responsibility, including author inheritance, person names, link attributes, valid identifiers, and required entry content or alternate links.

Use stable absolute identifiers. updated represents modification time; published is optional publication time. Dates accept DateTimeInterface and CakePHP date-only objects, integer timestamps, and parseable strings and render as RFC 3339 values.

Text

Plain strings are XML-escaped text. HTML uses:

$feed['entries'][0]['content'] = ['@type' => 'html', '@' => '<p>Published HTML</p>'];

HTML text constructs are CDATA-wrapped. Sanitize untrusted HTML before publishing it. XHTML text constructs are unsupported and raise SerializationFailureException; use text or HTML instead. The same text handling applies to title, subtitle, rights, summary, and content.

Links

A string is an alternate link. Explicit links use XML attributes:

$feed['link'] = [
    ['@href' => 'https://example.org/', '@rel' => 'alternate'],
    ['@href' => 'https://example.org/feeds.atom', '@rel' => 'self', '@type' => 'application/atom+xml'],
];

CakePHP URL arrays are also accepted and resolved to absolute URLs. Lists support several links. For media enclosures use @rel => 'enclosure' with URL, MIME type, and byte length; Atom does not use the RSS enclosure shorthand.

People and categories

A bare author string becomes a person name. Structured people support name, email, and URI; lists represent multiple people. Contributors use the same shape:

$feed['author'] = ['name' => 'Example editor', 'email' => 'editor@example.org'];
$feed['category'] = ['@term' => 'news', '@scheme' => 'https://example.org/tags', '@label' => 'News'];

Categories also accept strings and lists. Entry source can contain metadata for the originating feed.

Namespaces

The Atom default namespace is automatic. Built-in extension prefixes are dc, content, and itunes. A top-level namespace map registers custom prefixes:

$feed['namespace'] = ['ex' => 'https://example.org/feed-extension'];
$feed['ex:owner'] = 'Example publisher';

Use explicit HTML text constructs for markup; Atom extension values such as content:encoded are not automatically treated as HTML. Register every custom prefix used by your extension data.