module RSS - rss: Ruby Standard Library Documentation

# module RSS

# `RSS` reading and writing¶ ↑

Really Simple Syndication (`RSS`) is a family of formats that describe ‘feeds,’ specially constructed `XML` documents that allow an interested person to subscribe and receive updates from a particular web service. This portion of the standard library provides tooling to read and create these feeds.

The standard library supports `RSS` 0.91, 1.0, 2.0, and `Atom`, a related format. Here are some links to the standards documents for these formats:

- `RSS`

  - 0.9.1

  - 1.0

  - 2.0

- Atom

## Consuming `RSS`¶ ↑

If you’d like to read someone’s `RSS` feed with your Ruby code, you’ve come to the right place. It’s really easy to do this, but we’ll need the help of open-uri:

    require 'rss'
    require 'open-uri'

    url = 'http://www.ruby-lang.org/en/feeds/news.rss'
    URI.open(url) do |rss|
      feed = RSS::Parser.parse(rss)
      puts "Title: #{feed.channel.title}"
      feed.items.each do |item|
        puts "Item: #{item.title}"
      end
    end

As you can see, the workhorse is RSS::Parser#parse, which takes the source of the feed and a parameter that performs validation on the feed. We get back an object that has all of the data from our feed, accessible through methods. This example shows getting the title out of the channel element, and looping through the list of items.

## Producing `RSS`¶ ↑

Producing our own `RSS` feeds is easy as well. Let’s make a very basic feed:

    require "rss"

    rss = RSS::Maker.make("atom") do |maker|
      maker.channel.author = "matz"
      maker.channel.updated = Time.now.to_s
      maker.channel.about = "http://www.ruby-lang.org/en/feeds/news.rss"
      maker.channel.title = "Example Feed"

      maker.items.new_item do |item|
        item.link = "http://www.ruby-lang.org/en/news/2010/12/25/ruby-1-9-2-p136-is-released/"
        item.title = "Ruby 1.9.2-p136 is released"
        item.updated = Time.now.to_s
      end
    end

    puts rss

As you can see, this is a very Builder-like DSL. This code will spit out an `Atom` feed with one item. If we needed a second item, we’d make another block with maker.items.new_item and build a second one.

## Copyright¶ ↑

Copyright © 2003-2007 Kouhei Sutou <kou@cozmixng.org>

You can redistribute it and/or modify it under the same terms as Ruby.

There is an additional tutorial by the author of `RSS` at: www.cozmixng.org/~rwiki/?cmd=view;name=RSS+Parser%3A%3ATutorial.en

### Constants

AVAILABLE_PARSERS

  The list of all available parsers, in constant form.

AVAILABLE_PARSER_LIBRARIES

  The list of all available libraries for parsing.

CONTENT_PREFIX

  The prefix for the Content `XML` namespace.

CONTENT_URI

  The `URI` of the Content specification.

DC_PREFIX

  The prefix for the Dublin Core `XML` namespace.

DC_URI

  The `URI` of the Dublin Core specification.

DublincoreModel

  For backward compatibility

IMAGE_ELEMENTS

  This constant holds strings which contain the names of image elements, with the appropriate prefix.

IMAGE_PREFIX

  The prefix for the Image `XML` namespace.

IMAGE_URI

  The `URI` for the Image specification.

ITUNES_PREFIX

  The prefix for the iTunes `XML` namespace.

ITUNES_URI

  The `URI` of the iTunes specification.

SLASH_PREFIX

  The prefix for the Slash `XML` namespace.

SLASH_URI

  The `URI` of the Slash specification.

SY_PREFIX

  The prefix for the Syndication `XML` namespace.

SY_URI

  The `URI` of the Syndication specification.

TAXO_ELEMENTS

  The listing of all the taxonomy elements, with the appropriate namespace.

TAXO_PREFIX

  The prefix for the Taxonomy `XML` namespace.

TAXO_URI

  The `URI` for the specification of the Taxonomy `XML` namespace.

URI

  The `URI` of the `RSS` 1.0 specification

VERSION

  The current version of `RSS`