Cs 891 2rev B

Atom: The Atom Syndication Format RFC 4287 - M. Nottingham and R. Sayre (editors) and hAtom 0.1 David Janes, Benjamin Carlyle, and Tantek Celik Presented by: Chuck Cartledge and Carlton Northern

Trying to set the tone.
“ In the Developer’s Bars of the world – those dark, sordid places filled with grizzled coders and their clans – a special corner is always reserved for the developers of content-syndication standards. There, weeping in their beer, you’ll find veterans of a long and difficult process. Most likely, they will have the Thousand Yard Stare of those who have seen more than they should. The standards you read about in the this book were not born fresh and innocent, of a streamlined process overseen by the Wise and Good. Rather the following chapters have been dragged into the world and tempered through brawls, knife fights, and the occasional riot.”
Ben Hammersley, “Developing Feeds with RSS and Atom,” O’Reilly Media, Inc., 2005, ISBN 0-596-0081-3

What we will cover and how
What are RFCs and why should we care
Where Atom fits in the Grand Scheme of things
How Atom compares with RSS
How Atom compares with RSS 2.0
Atom, the RFC
Atom, the Simplest Feed
Demonstration of Atom Feeds
Atom compared to hAtom?
Our conclusions
Questions for you

What is an RFC and why should we care?
Request for Comments (RFCs) are the glue that allows the I’net to work
Draft RFCs (Internet Drafts) are submitted to the Internet Engineering Task Force (IETF) for review and comments
IDs are assigned a sequential number and released for comment
RFCs are the standards that anyone wanting to “play” on the I’net have to adhere to
RFCs that we have addressed in class – 4287, 5005, 4685, 4946, 5023,
RFCs that it would be nice to address in class – 1149 and 2549
The I’net works because people do things IAW the RFCs. It is the “law.”
www.ipv6style.jp/jp/20061220/ietf1.html

How does Atom fit into the Grand Scheme of Things?
“… in 2003, it became painfully clear that the RSS world was not going to declare a truce and agree to sort things out … a large group of developers split off to design a new format from the ground up. After much tooing, foring, cogitating, and argument, not the least over the name of the thing, a format has arisen: the Atom Syndication Format.”
Ben Hammersley, “Developing Feeds with RSS and Atom,” O’Reilly Media, Inc., 2005, ISBN 0-596-0081-3 http://en.wikipedia.org/wiki/Syndication_format_family_tree

How does Atom compare with RSS?
“ So, there are now two basic formats for syndicating a web site. RSS is older with many different versions, Atom is newer, more standard, and only beginning to be adopted. Atom was constructed to work across a wide variety of platforms and devices.”
http://www.commoncraft.com/archives/000592.html
Atom is documented in RFCs
4287 The Atom Syndication Format, Dec. 2005
4685 Atom Threading Extensions, Sept 2006
5023 The Atom Publishing Protocol , Oct. 2007
RSS has various flavors and mutually incompatible implementations

How does Atom compare to RSS 2.0?
RSS
Content model – plain text or escaped HTML, no way to distinguish
Date formats – based on RFC 822
Internationalization – can identify feed, but not items
Modularity/reuse – not part of the design
Atom
Content model – explicitly and unambiguously labels the type of content being provided by the entry
Date formats – based on RFC 3339 (a subset of ISO 8601)
Internationalization – uses xml:lang to make it possible to specify a language for every piece of human readable content
Modularity/reuse – specifically designed to allow elements to be reused
Atom gives a good deal of info about the resource and the content, but leaves the meaning of the content to RSS
http://en.wikipedia.org/wiki/Atom_(standard)

Atom: The RFC
Two kinds of Atom Documents
Feeds – represents an Atom Feed
Metadata about the feed
Some or all entries associated with the feed
Entries
Exactly one entry
Outside of an Atom feed
Atom documents MUST be well-formed XML
Atom is extensible

Atom: The RFC – Verbose or Concise
RFC Specification in two different formats
Verbose (words, words, lots of words)
Concise Relax NG schema
Verbose:
3.1.1. The "type" Attribute Text constructs MAY have a "type" attribute. When present, the value MUST be one of "text", "html", or "xhtml". If the "type" attribute is not provided, Atom Processors MUST behave as though it were present with a value of "text". Unlike the atom:content element defined in Section 4.1.3, MIME media types [MIMEREG] MUST NOT be used as values for the "type" attribute on Text constructs.
Concise
atomPlainTextConstruct = atomCommonAttributes,
attribute type { "text" | "html" }?,
text atomXHTMLTextConstruct = atomCommonAttributes,
attribute type { "xhtml" },
xhtmlDiv
Verbose has implementation guidance as well as semantic information

Atom: The RFC – Relaxed NG Symbols
A schema language for XML
On track to become ISO Standard 19757-2
A language agnostic schema that can be processed language specific parsers
For our purposes limited XML-tag following operators are of interest:
* => 1 or more occurrences
? => less than or equal to 1 occurrence
null => exactly one occurrence
http://www.relaxng.org/
http://books.xmlschemata.org/relaxng/

Atom: The RFC – Example of Relaxed NG Common Attributes
atomCommonAttributes =
attribute xml:base { atomUri }?,
attribute xml:lang { atomLanguageTag }?, undefinedAttribute*

Atom: The RFC Partial Relaxed NG atom:feed
start = atomFeed | atomEntry
atomPersonConsruct =
(element atom:name {text}
& element atom:uri { atomUri }?
…
atomFeed = [ … various rules …]
Element atomFeed { …
atomAuthor*
… }
atomAuthor = element atom:author { atomPersonConstruct }

Atom: The Simplest Feed
<?xml version="1.0" encoding="utf-8"?>
<feed version="draft-ietf-atompub-format-03: do not deploy"
xmlns="http://purl.org/atom/ns#draft-ietf-atompub-format-03">
<head>
<title>The Simplest Feed</title>
<link rel="alternate" type="text/html"
href="http://example.org/index.html"/>
<author><name>Ben Hammersley</name></author>
<updated>2004-10-25T15:07:02Z</updated>
</head>
<entry>
<title>The Simplest Entry Document</title>
<link rel="alternate" type="text/html" href="http://example.org/example_entry"/>
<author><name>Ben Hammersley</name></author>
<id>http://example.org/2004/12345679</id>
<updated>2004-10-25T15:07:02Z</updated>
<content type="TEXT">Simple Simple Simple</content>
</entry>
</feed>
Ben Hammersley, “Developing Feeds with RSS and Atom,” O’Reilly Media, Inc., 2005, ISBN 0-596-0081-3

An example of an Atom client application
Perl code from O’Reily’s book

An example of an Atom consolidator
Expand Perl code to pull data periodically and put into a standard file

An example of a web client
Basic HTML that does a periodically does a refresh of the file from the previous slide.

Google Reader Demo
http://carrotrevolution.blogspot.com/

What is hAtom?
A microformat conceptually based on the Atom Syndication Format.
Identifies semantic information in weblog posts, news feeds or similarly formatted content.
hAtom is not intended to replace RSS or Atom.

Why hAtom?
Provides a simple way to markup blog posts in the actual (X)HTML, eliminating the need of creating a separate file for RSS or Atom.
Use cases:
Make your web page your feed.
Provide a more semantic meaning to a blog without adding the overhead of implementing everything needed for an Atom or RSS feed.
For articles that were created before structuring syndication formats such as RSS and Atom, convert them to hAtom to give them structure and semantic meaning.

What is a Microformat?
A simple, open data format used to structure and represent very specific types of content on the web.
Microformats: real world semantics, AKA lowercase semantic web. ¹
Example: hCard is a microformat for representing people, companies, organizations, and places, using vCard.
Demo: http:// microformats.org/code/hcard/creator
¹ http://www.tantek.com/presentations/2004etech/realworldsemanticspres.html

List of Microformats
hCalendar – for marking up calendar events.
hCard – for marking up people, companies, organizations, and places.
hAtom – for marking up primarily blog posts.
hResume – for marking up resumes.
hReview – for marking up reviews.
xFolk – for marking up bookmarks.
VoteLinks – for marking up polls/votes.
XFN – for marking up relationships between people.
XMDP – for marking up metadata profiles.
adr – for marking up addresses.
geo – for marking up geographical coordinates.
There are more that are not listed here, and many more to come!

Microformats Demo
Using Firefox and the extension “Operator” we can see some pretty interesting stuff.
http://www.w3.org/People/Connolly/events/

How to Use hAtom?
Use the hAtom2Atom XSLT to convert hAtom to Atom.
Demo: http://lukearno.com/projects/hatom2atom/ using this input http://placenamehere.com/

Semantic XHTML Design Principles
hAtom and other microformats conform to semantic XHTML design principles.
Semantic XHTML, as opposed to presentational XHTML, deals with the identification of relationships and information.
Rules:
Reuse, Reuse, Reuse!!!
Be precise.
Use similar or same naming conventions as the original schema.

hAtom Schema Elements
hfeed - optional.
feed category – optional, keywords or phrases, using rel -tag .
hentry - required
entry-title – required, text.
entry-content – optional, text.
entry-summary - optional, text.
updated - required using datetime -design-pattern .
published - optional using datetime -design-pattern .
author - required using hCard .
bookmark (permalink) - optional, using rel -bookmark .
tags - optional, keywords or phrases, using rel -tag .

hAtom Example
Canned example: http://microformats.org/wiki/hatom-examples
Example in the wild: http://placenamehere.com/

What is the relationship between Atom and hAtom?
hAtom is derived from Atom.
Atom can be used to syndicate any kind of content that is frequently updated.
hAtom can technically be used to markup any content that can be syndicated by Atom, but is generally used for blog posts.
Atom can be constructed from hAtom. This is how documents that use hAtom are usually syndicated.
hAtom uses very similar, or exactly the same attributes as Atom.

hAtom and Atom Schema Comparison

Conclusion
Recap Atom versus RSS
Multiple non-standard formats
Syntax and recommended processing in the public domain
Designed based on lessons learned from RSS
Atom
Pure XML
Moderate, but limited defined tag set
Describes feeds and entries
Extensibility built in
Differences between Atom and hAtom

Our Questions for You
What is the purpose of an RFC? And, how do we know that an RFC has done its job?
When is hAtom a better choice than Atom?
What kinds of problems are unique to providing feeds to handheld devices?

Sources
http://microformatique.com/?page_id=138
http://www.tantek.com/presentations/2004etech/realworldsemanticspres.html

Cs 891 2rev B

by carlton.northern on Feb 28, 2008

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Cs 891 2rev B — Presentation Transcript