# 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'
    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