Pagination for syndication feeds

[nrako]

This might be a 🐇🕳️

The current library used to create the feeds do not support pagination: jpmonette/feed#84

This is also a gray area in RSS 2.0, in other ATOM & JSON this is well supported.

RSS 2.0

RSS 2.0 itself does not inherently support pagination. The RSS 2.0 specification, as originally released, focuses on providing a feed format for delivering updates to users, including items such as news articles, blog posts, and other content. The specification includes elements for describing the feed and its items but does not include built-in features for pagination, which would allow clients to fetch a subset of items based on a specific page number or limit.

However, pagination can still be implemented with RSS 2.0 feeds through various approaches, depending on the requirements of the publisher and the capabilities of the consuming application. Here are a few common methods:

1. Custom Elements: Feed publishers can add custom elements to their RSS feeds to indicate pagination controls or information. These might include elements specifying the current page, total number of items, total pages, and links to next or previous pages. Consuming applications that understand these custom elements can then use them to navigate the feed in a paginated manner.

2. Feed Segmentation: Publishers can segment their feeds into multiple, smaller feeds based on criteria such as date ranges, categories, or arbitrary pagination. Each segmented feed would represent a "page" of content. This approach requires the consumer to know how to access these segmented feeds, typically through different URLs.

3. Query Parameters: Some feed providers allow clients to request paginated feeds by appending query parameters to the feed URL (e.g., ?page=2&limit=10). This approach is controlled by the server-side implementation and requires the feed consumer to modify the feed URL according to the pagination scheme supported by the provider.

4. Link Elements: Although not a standard part of RSS 2.0, some feeds include <link> elements (not to be confused with the standard <link> element within an item) or other mechanisms in the feed metadata to provide URLs for pagination. These links can point to the next, previous, first, and last pages of content.

It's important to note that since these methods are not standardized within the RSS 2.0 specification, their support and implementation can vary widely. Consumers of RSS feeds need to rely on documentation provided by the feed publishers or inspect the feeds to determine if and how pagination is implemented.

Atom 1.0

Atom 1.0, unlike RSS 2.0, includes built-in support for pagination, which is a significant advantage for managing large feeds or for applications needing to process feed data in chunks. Pagination in Atom feeds is commonly handled through the use of link elements with rel attributes indicating their relationship to the current feed document. Here's how it works:

Pagination Elements in Atom 1.0

• <link rel="next">: This link points to the next "page" of entries in the feed. It indicates that there is more content available beyond what is currently being viewed or processed.
• <link rel="previous"> or <link rel="prev">: Similar to the "next" link but in the opposite direction. It points to the previous page of entries, allowing navigation to earlier content in the feed.
• <link rel="first">: Points to the first page of entries in the feed. This can be useful for users or applications that want to navigate to the beginning of the feed content.
• <link rel="last">: Points to the last page of entries. This allows users or applications to jump directly to the most recent content, regardless of their current position in the feed.

Example

In an Atom feed, pagination links might appear as follows:

<link rel="first" href="http://example.com/feed?page=1" />
<link rel="prev" href="http://example.com/feed?page=2" />
<link rel="next" href="http://example.com/feed?page=4" />
<link rel="last" href="http://example.com/feed?page=10" />

Implementation Notes

• Dynamic Content: Since Atom feeds often represent dynamic content (e.g., blog posts, news articles), the pagination links can change as new content is added. Clients consuming the feed should be prepared to handle these changes.
• Server-Side Support: Effective pagination requires support from the server generating the Atom feed. The server needs to calculate and insert the appropriate pagination links based on the total content available and the current position within that content.
• Client-Side Processing: Clients consuming Atom feeds with pagination support should be able to recognize these link elements and use them to navigate through the feed content efficiently, fetching additional pages of entries as needed.

Pagination in Atom 1.0 feeds provides a standardized way to navigate through large sets of feed entries, making it easier for both publishers and consumers to manage and consume feed content effectively.

JSON Feed 1.0

JSON Feed 1.0 supports pagination in a straightforward and flexible manner, similar to Atom 1.0, by utilizing link objects within the feed. These link objects can specify URLs for the next page of content, previous page, and other navigational links, depending on the publisher's implementation. Here's how it works:

Pagination in JSON Feed 1.0

• next_url: This is a key in the JSON Feed object that points to the URL of the next page of items. When present, it indicates that there are more items to fetch beyond what is included in the current feed document.
• _prev_url: Though not officially part of the JSON Feed specification, some implementations might include a similar key for the previous page URL, following the naming convention (_prev_url) or a similar one, to maintain consistency with next_url. However, because this is not standardized, its support and naming could vary.

Example

A JSON Feed with pagination might look something like this:

{
  "version": "https://jsonfeed.org/version/1",
  "title": "My Example Feed",
  "home_page_url": "http://example.com/",
  "feed_url": "http://example.com/feed.json",
  "items": [
    {
      "id": "2",
      "content_text": "This is a second item.",
      "url": "http://example.com/second-item"
    },
    {
      "id": "1",
      "content_text": "This is a first item.",
      "url": "http://example.com/first-item"
    }
  ],
  "next_url": "http://example.com/feed.json?page=2"
}

Implementation Notes

• Flexibility: JSON Feed allows for a flexible implementation of pagination, with the primary method being through the next_url. Publishers can also include custom keys for additional navigational links if they choose, but such implementations should be documented for consumers of the feed.
• Dynamic Content Management: As with Atom, managing dynamic content via pagination in JSON Feed requires the publisher to dynamically generate the next_url (and potentially other navigational links) as content is added or as the feed is requested.
• Client-Side Handling: Clients consuming JSON Feeds should be prepared to handle pagination by detecting the presence of next_url and making additional requests as needed to fetch the entire content of the feed.

Pagination support in JSON Feed 1.0 makes it easier for both publishers and consumers to manage and navigate large sets of data in a feed, providing a simple yet effective mechanism for content discovery and consumption.