How Does RSS Work?
Overview
RSS acts as an infrastructure layer. A publisher hosts a structured XML file at a permanent URL. A consumer fetches that URL at regular intervals, parses the data, and triggers actions based on new entries.
This architecture decouples the publisher from the reader. The publisher doesn't need to know who is reading the feed, and the consumer doesn't need to understand the website's visual layout. The XML file is the stable contract between them.
The Source–Feed–Consumer Model
Every RSS workflow relies on three components:
The Source: Where the content originates (a blog, news site, or social profile). The source owns the data.
The Feed: An XML file served at a specific URL. It acts as the interface: a machine-readable version of the source that stays the same even if the website is redesigned.
The Consumer: Any software that reads the feed. This includes feed readers, automation platforms (Zapier/Make/n8n), or AI ingestion pipelines. The consumer "polls" the URL, compares the content to previous fetches, and processes new items.
What is Inside an RSS Feed?
An RSS feed uses standardized fields so that automation remains deterministic. You never have to "guess" where the data is.
Channel-Level Fields
Every feed begins with channel metadata describing the source:
<title>— The name of the feed or source<link>— The URL of the source website<description>— A brief description of what the feed contains<language>— The primary language of the content<lastBuildDate>— When the feed was last generated
Item-Level Fields
Each entry in the feed represents one update:
<title>— The headline or title of the item<link>— The permanent URL where the full content lives<pubDate>— When the item was published (RFC 822 format)<guid>— A unique identifier that never changes for this item<description>— Summary or full content of the item
How Updates Are Detected: The Power of the GUID
RSS uses a polling model for update detection. Consumers periodically request the feed URL and compare the response to what they have seen before.
The <guid> field is the anchor of this process. When a consumer polls a feed, it checks each item's GUID against its stored list of known GUIDs. Items with new GUIDs are treated as new content. Items with known GUIDs are skipped.
This prevents common automation errors:
- Edits: If a headline is edited but the GUID stays the same, no duplicate alert is triggered.
- Rendering: If an old post moves to the top of the feed, the system knows it isn't "new" because of the GUID.
- Updates: If items are reordered in the feed, GUIDs identify what is actually new.
Why XML?
While modern APIs often use JSON, RSS remains built on XML for three technical reasons:
Deterministic parsing. XML has a strict specification. A valid XML document parses the same way in every language and on every platform.
Hierarchical structure. The tags clearly define the hierarchy (Feed → Items → Fields), making the data model obvious to any machine.
Longevity. XML tooling exists in every programming language. An RSS feed created twenty years ago can still be read by any modern system today.
Where RSS.app Fits: Creating the Missing Interface
In the usual Source–Feed–Consumer model, the Source provides the Feed. However, many modern platforms do not provide a native XML interface.
This is where RSS.app fits into the architecture. It acts as an Interface Provider, sitting between the Source and the Feed:
1. Bridging the Gap
For websites that do not offer RSS natively, RSS.app monitors the Source's HTML and generates the RSS Feed automatically. This allows any website to be integrated into the Source–Feed–Consumer model as if it had a native RSS output.
2. The Standardization Layer
Even when a website provides a native feed, the data can be inconsistent or "noisy." RSS.app acts as a quality control layer to ensure the feed is production-ready:
- Data Normalization: Converting non-standard date formats into valid timestamps.
- Schema Correction: Fixing broken XML code that would otherwise crash automation tools.
- Media Enrichment: Extracting images and thumbnails from the source and placing them in standardized
<enclosure>tags.
3. Technical Uniformity
From the perspective of the Consumer, there is no distinction between a native feed and one generated by RSS.app. The technical exchange is identical. This uniformity allows organizations to build a single, consistent data pipeline that handles everything from a small blog to a global social media platform using the exact same logic.
Frequently Asked Questions
How often do RSS feeds update?
RSS feeds update whenever the source publishes new content. There is no fixed schedule—feeds reflect the source's publishing frequency. Consumer applications typically poll feeds every 15 minutes to 1 hour, though this varies by tool and use case.
What is polling in the context of RSS?
Polling means periodically checking a feed URL for new content. Unlike push notifications where servers send updates to clients, RSS uses a pull model where clients request the feed at intervals they control. This gives consumers full control over when and how often they check for updates.
What is a GUID and why does it matter?
A GUID (Globally Unique Identifier) is a permanent identifier for each item in a feed. It allows consumers to reliably detect new items even if titles or links change. Without GUIDs, a simple title edit could make an old item appear as new content.
Can RSS feeds be password protected?
Yes. RSS feeds can be served behind HTTP authentication or with token-based URLs. Private feeds work the same as public feeds—the protection happens at the HTTP layer, not in the RSS format itself.
What happens if a feed is temporarily unavailable?
Well-designed feed consumers handle temporary failures gracefully. They cache the last successful response and retry after a delay. The RSS format does not change—the resilience comes from how consumers implement polling and caching.
Is there a size limit for RSS feeds?
There is no technical limit in the RSS specification, but practical limits exist. Most feeds contain 10-50 recent items to keep file sizes manageable. Larger archives are typically handled through pagination or separate archive feeds.
How do podcasts use RSS differently?
Podcasts use RSS with enclosure tags that point to audio files. The feed structure is identical to any other RSS feed, but items include media attachments. Podcast apps are essentially specialized RSS readers that know how to handle audio enclosures.
Can RSS feeds include full article content?
Yes. Publishers choose whether to include full content or just summaries. The description field can contain complete articles with HTML formatting, or brief excerpts that link to the full piece. Some feeds use a separate content:encoded field for full HTML content.