CIT 383: Administrative Scripting Slide #1

CIT 383: Administrative Scripting

RSS

CIT 383: Administrative Scripting

Topics

1. Web Feeds

2. Aggregators

3. RSS

4. Atom

5. Feeds in Ruby

CIT 383: Administrative Scripting

Web Feeds

A web feed is a data format used for providing users with frequently updated information, like weather, news, comments. Content providers syndicate a web feed by

providing it via a URL on their web site. Readers subscribe to a web feed to get updates. Software like RSS Bandit or Google Reader

aggregate multiple web feeds in a single interface so user does not have to visit sites to check for updates manually.

CIT 383: Administrative Scripting

What data is available via feeds? Blogs Blog comments Tagged blog entries Music News Pictures (from Flickr) Social networking sites Transport schedules (Google Transit) Videos Weather

CIT 383: Administrative Scripting

Feeds vs E-mail

Web Feeds User pulls content

from provider. Provider doesn’t

know user e-mail. Unsubscribe by

configuring client.

E-mail Provider pushes

content to user. Provider has user e-

mail address. Unsubscribe by

contacting provider.

CIT 383: Administrative Scripting

Aggregators

CIT 383: Administrative Scripting

Aggregators

Browser Firefox (live bookmarks) Firefox Sage add-on IE 7 Opera

Standalone Akregator BottomFeeder Liferea RSS Bandit

Online AmphetaDesk Bloglines Fastladder Google Reader

Indirect iGoogle MyYahoo sidebars

CIT 383: Administrative Scripting

Web Feed Formats

Web feeds include both content and metadataContent: Title, link, full or summarized text

Metadata: Author, publication date

XML-data formatsAtom

RSS

CIT 383: Administrative Scripting

RSS Variants

RSS-DEV Working GroupRDF Site Summary 0.90 from Netscape

RDF Site Summary 1.0

Harvard’s Berkman CenterRich Site Summary 0.91 from Netscape

Really Simple Syndication 2.0

CIT 383: Administrative Scripting

RSS 1.0 Example

CIT 383: Administrative Scripting

Atom

Alternative to RSS, published as RFC 4287.

Features: Requires title, unique ID, and last updated time. Payload container specifies content type

Plain text Escaped or well-formed HTML Base64-encoded binary data

Separate summary and content elements. Standardizes feed autodiscovery.

CIT 383: Administrative Scripting

Atom Example

CIT 383: Administrative Scripting

Ruby Feeds

RSS Part of Ruby core library. Parses and writes RSS.

FeedTools Available as a gem. Parses Atom and RSS. Can convert between Atom and RSS versions.

Rails Can write Atom and RSS feeds.

CIT 383: Administrative Scripting

FeedTools

require ‘feed_tools’

url = ‘http://www.pragprog.com/podcasts/feed.rss’

feed = FeedTools::Feed.open(url)

feed.entries.each_with_index do |entry,i|

puts “#{i} #{entry.title}”

end

CIT 383: Administrative Scripting Slide #15

References1. Michael Fitzgerald, Learning Ruby, O’Reilly,

2008.2. David Flanagan and Yukihiro Matsumoto, The

Ruby Programming Language, O’Reilly, 2008.3. Hal Fulton, The Ruby Way, 2nd edition, Addison-

Wesley, 2007.4. Robert C. Martin, Clean Code, Prentice Hall,

2008.5. Dave Thomas with Chad Fowler and Andy Hunt,

Programming Ruby, 2nd edition, Pragmatic Programmers, 2005.