Metadata Proposal

BottomFeeder MetaData Proposal

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This document is a work-in-progress -- assume errors and omissions! Tell me what to fix. Send comments to Rich Demers

Last updated on June 4, 2003

Introduction

RSS stands for Really Simple Syndication or RDF Site Summary, depending on which version of the standards you read. Six versions are in current use, plus a variety of modules, corresponding to XML namespaces, have been added to make RSS more descriptive or more functional. This makes it difficult for producers to know how to build RSS files -- too many choices. And it makes it difficult for aggregators because there are too many variations to handle.

This document attempts to resolve this problem for the BottomFeeder aggregator by identifying general rules for handling elements, and by identifying how RSS elements should be individually handled.

RSS Versions

Version	Standard or Module
0.9	RSS 0.9
0.91	RSS 0.91
0.92	RSS 0.92. RSS 0.92 is upward compatible with RSS 0.91, with the noted additional elements.
0.93	RSS 0.93. RSS 0.93 is upward compatible with RSS 0.92 and RSS 0.91, with the noted additional elements.
1.0	RSS 1.0. RSS 1.0 is upward compatible with RSS 0.9, but with an RDF syntax and extension through modules.
content	RSS 1.0 Content Module
sy	RSS 1.0 Syndication Module
admin	RSS 1.0 Administrative Module
2.0	RSS 2.0
dc	Dublin Core Module
tb	Trackback Module
pb	Pingback Module
geo	RDF Geographical Module
icbm	ICBM Geographical Module
wfw	Well Formed Web Comment API Module

Element Normalization Table

The element normalization table alphabetically lists all metadata elements of all the RSS standards plus those of some important modules. It identifies which metadata elements are equivalent, and specifies how BottomFeeder should use them. This table is deliberately redundant across versions so that equivalences and differences are more visible.

1. Each element is associated with a BottomFeeder identifier; elements with the same identifier are used the same way (displayed, searched, browsed, etc.). Click identifiers shown as links to go to the specification of how that element is used.
2. Some elements with different names from different standards or modules have the same meaning. If more than one such element (or more than one instance of the same element) appears in the same containing element, BottomFeeder takes the contents of the last such element found.
3. Element Table Legend:

   BottomFeeder Use	Description
   tbd	to be decided
   browse	open a browser
   property	display as a property
   tree	display in BF tree
   table	display in BF Item List table
   banner	display in BF Feed Banner
   page	display in BF Item pane
   search	can be included in a search expression
   feedback	used to provide feedback
   updating	affects how BF updates the channel
   map	open browser to mapping website
   pingback	as defined by Pingback Module
   trackback	as defined by Trackback Module

RSS Element			BottomFeeder Element
Version	Name	In	Identifier	Label	Use	Definition
pb	about	item	item_pbAbout	about	pingback	A pingback target URL that was pinged in reference to this item.
tb	about	item	item_tbAbout	about	trackback	A trackback URL that was pinged in reference to this item.
geo	altitude	channel point	feed_altitude	altitude	tbd	The altitude of the source of the feed.
geo	altitude	item point	item_altitude	altitude	tbd	The altitude of the source of the item.
2.0	author	item	item_creator	creator	property search	Email address of the author of the item.
xhtml	body	item	item_description
0.92	category	item	item_category	category	property search	One or more categories that the item belongs to.
0.93	category	item	item_category
2.0	category	channel	feed_category	category	tbd	One or more categories that the feed belongs to.
2.0	category	item	item_category
0.92	cloud	channel	feed_cloud	cloud	tbd	A URI to be notified of updates to the feed, that implements a lightweight publish-subscribe protocol for feeds.
0.93	cloud	channel	feed_cloud
2.0	cloud	channel	feed_cloud
wfw	comment	item	item_comment	comment	feedback	URI to post an item fragment with a comment on the item.
2.0	comments	item	item_comment
dc	contributor	channel	feed_contributor	contributor	property	An entity responsible for making contributions to the content of the feed.
dc	contributor	item	item_contributor	contributor	property search
0.91	copyright	channel	feed_copyright	copyright	property	Copyright notice for content in the feed.
0.92	copyright	channel	feed_copyright
0.92	copyright	item	item_copyright	copyright	property search	Copyright notice for content in the item.
0.93	copyright	channel	feed_copyright
0.93	copyright	item	item_copyright
2.0	copyright	channel	feed_copyright
2.0	copyright	item	item_copyright
dc	coverage	channel	feed_coverage	coverage	property	The extent or scope of the content of the feed.
dc	coverage	item	item_coverage	coverage	property search	The extent or scope of the content of the item.
dc	creator	channel	feed_creator	creator	property	An entity primarily responsible for making the content of the feed.
dc	creator	item	item_creator
dc	date	channel	feed_pubDate	publication date	property	A date associated with an event in the life cycle of the feed.
dc	date	item	item_pubDate	publication date	property search	A date associated with an event in the life cycle of the item.
all	description	channel	feed_description	description	tbd	Text that describes the feed.
all	description	item	item_description	description	search page	Text that describes the item.
all	description	textInput	feedback_description	feedback	tbd	Text that describes the kind of feedback supported.
all	description	image	image_description	description	tbd	Text describing the image.
0.91	docs	channel	feed_docs	format documents	property	A URL that points to the documentation for the format used in the feed.
0.92	docs	channel	feed_docs
0.93	docs	channel	feed_docs
2.0	docs	channel	feed_docs
0.92	enclosure	item	item_enclosure	enclosure	property	Describes a media object that is attached to the item.
0.93	enclosure	item	item_enclosure
2.0	enclosure	item	item_enclosure
content	encoded	item	item_description
content	encoding	channel	feed_encoding	encoding	property	A URI representing the encoding of a content:item.
content	encoding	item	item_encoding	encoding	property	A URI representing the encoding of a content:item.
admin	errorReportsTo	channel	feed_errorReportsTo	report errors to	property	A URI (typically a 'mailto:' URL) for contacting the person or source of the feed.
admin	errorReportsTo	item	item_errorReportsTo	report errors to	property	A URI (typically a 'mailto:' URL) for contacting the person or source of the item.
0.93	expirationDate	item	item_expirationDate	expiration date	property	Indicates when an item is no longer available.
content	format	channel	feed_format	format	property	A URI representing the format of a content:item.
content	format	item	item_format
dc	format	channel	feed_format
dc	format	item	item_format	format	property search	The physical or digital manifestation of the channel or item.
2.0	generator	channel	feed_generator	generator	property	A string indicating the program used to generate the channel.
admin	generatorAgent	channel	feed_generatorAgent
2.0	guid	channel	feed_identifier	identifier	property	A string that uniquely identifies the channel.
2.0	guid	item	item_identifier	identifier	property search	A string that uniquely identifies the item.
0.91	height	image	image_height	image height	banner	The height a displayed image should have.
0.92	height	image	image_height
0.93	height	image	image_height
2.0	height	image	image_height
dc	identifier	channel	feed_identifier
dc	identifier	item	item_identifier
content	item	item	item_description
1.0	items	channel	feed_items	items	tbd	A table of contents of the channel's items.
content	items	channel	feed_items
0.91	language	channel	feed_language	language	property	The natural language of the content of the feed.
0.92	language	channel	feed_language
0.93	language	channel	feed_language
2.0	language	channel	feed_language
dc	language	channel	feed_language
dc	language	item	item_language	language	property search	The natural language of the content of the item.
0.91	lastBuildDate	channel	feed_lastBuildDate	last build date	updating property	The last time the feed was generated.
0.92	lastBuildDate	channel	feed_lastBuildDate
0.93	lastBuildDate	channel	feed_lastBuildDate
2.0	lastBuildDate	channel	feed_lastBuildDate
geo	latitude	channel point	feed_latitude	latitude	property map	The latitude of the source of the feed.
geo	latitude	item point	item_latitude	latitude	tbd	The latitude of the source of the item.
icbm	latitude	channel	feed_latitude
icbm	latitude	item		item_latitude
geo	longitude	channel	feed_longitude		property map
geo	longitude	item	item_longitude	longitude	tbd
icbm	longitude	channel	feed_longitude	longitude	property map
icbm	longitude	item	item_longitude
all	link	channel	feed_link	link	property browse	The URL of the resource covered by the feed.
all	link	item	item_link	link	property page browse	The URL to an item of the resource of the feed.
all	link	image	image_link	link	tbd	The URL to an image.
all	link	textInput	feedback_link	link	"execute CGI script"	The URL to send feedback to.
0.91	managingEditor	channel	feed_managingEditor	managing editor	property	Email address for person responsible for editorial content.
0.92	managingEditor	channel	feed_managingEditor
0.93	managingEditor	channel	feed_managingEditor
2.0	managingEditor	channel	feed_managingEditor
0.9	name	textInput	feedback_name	name	feedback	The name of the text object in the text input area.
0.91	name	textInput	feedback_name
1.0	name	textInput	feedback_name
0.92	name	textInput	feedback_name
0.93	name	textInput	feedback_name
2.0	name	textInput	feedback_name
tb	ping	item	item_tbPing	trackback ping	trackback	The item's trackback URL.
0.91	pubDate	channel	feed_pubDate		property
0.92	pubDate	channel	feed_pubDate
0.93	pubDate	channel	feed_pubDate
0.93	pubDate	item	item_pubDate		property search table
2.0	pubDate	channel	feed_pubDate
2.0	pubDate	item	item_pubDate
dc	publisher	channel	feed_publisher	publisher	property	An entity responsible for making the feed available.
dc	publisher	item	item_publisher	publisher	property search	An entity responsible for making the item available.
0.91	rating	channel	feed_rating	rating	property	The PICS rating for the channel.
0.92	rating	channel	feed_rating
0.93	rating	channel	feed_rating
2.0	rating	channel	feed_rating
dc	relation	channel	feed_relation	relation	property	A reference to a resource related to the feed.
dc	relation	item	item_relation	relation	property search	A reference to a resource related to the item.
dc	rights	channel	feed_copyright
dc	rights	item	item_copyright
pb	server	item	item_pbServer	pingback server	pingback	The URL of the item's pingback server.
0.91	skipDays	channel	feed_skipDays	skip days	updating	A hint for aggregators telling them which days they can skip.
0.92	skipDays	channel	feed_skipDays
0.93	skipDays	channel	feed_skipDays
2.0	skipDays	channel	feed_skipDays
0.91	skipHours	channel	feed_skipHours	skip hours	updating	A hint for aggregators telling them which hours they can skip.
0.92	skipHours	channel	feed_skipHours
0.93	skipHours	channel	feed_skipHours
2.0	skipHours	channel	feed_skipHours
0.92	source	item	item_source	source	property search	The feed that the item came from.
0.93	source	item	item_source
2.0	source	channel	feed_source	source	property	The resource that the feed came from.
2.0	source	item	item_source
dc	source	channel	feed_source
dc	source	item	item_source
dc	subject	channel	feed_category
dc	subject	item	item_category
pb	target	item	item_pbTarget	pingback target	pingback	The value that should be used as the target URI in a ping.
all	title	channel	feed_title	title	property banner	The name of the feed.
all	title	item	item_title	title	property search table	The name of the item.
all	title	image	image_title	title	tbd	The name of the image.
all	title	textInput	feedback_title	title	feedback	The label of the Submit button.
dc	title	channel	feed_title
dc	title	item	item_title
2.0	ttl	channel	feed_ttl	time to live	updating	The number of minutes a feed can be cached before refreshing from the source.
dc	type	channel	feed_type	genre	property	The nature or genre of the content of the feed.
dc	type	item	item_type	genre	property search	The nature or genre of the content of the item.
sy	updateBase	channel	feed_updateBase	update base date	updating	Defines a base date to be used in concert with updatePeriod and updateFrequency to calculate the publishing schedule.
sy	updatePeriod	channel	feed_updatePeriod	update period	updating	Describes the period over which the feed format is updated. Acceptable values are: hourly, daily, weekly, monthly, yearly. If omitted, daily is assumed.
sy	updateFrequency	channel	feed_updateFrequency	update frequency	updating	Used to describe the frequency of updates in relation to the update period. A positive integer indicates how many times in that period the feed is updated. If omitted a value of 1 is assumed.
0.9	url	image	image_link		banner
1.0	url	image	image_link
0.91	url	image	image_link
0.92	url	image	image_link
0.93	url	image	image_link
2.0	url	image	image_link
0.91	webMaster	channel	feed_webMaster	web master	property	Email address for person responsible for technical issues relating to the feed.
0.92	webMaster	channel	feed_webMaster
0.93	webMaster	channel	feed_webMaster
2.0	webMaster	channel	feed_webMaster
0.91	width	image	image_width	image width	banner	The width a displayed image should have.
0.92	width	image	image_width
0.93	width	image	image_width
2.0	width	image	image_width

BottomFeeder enhancements

One of my reasons for spending so much time on this Metadata Proposal was to get a handle on what kinds of metadata have been included in the various RSS standards and modules. Clearly, a lot of it exists to support complex querys by search engines and syndicators, but that doesn't mean BF should ignore it. BF does a great job of displaying the elements that make sense in BF's three-pane window, and in supporting searches into title, body and category. Now the question is, "What about the rest?" Should BF just ignore them or do we give users a meaningful way to work with them?

The current BF Feed Properties window does a fine job of presenting a limited number of operational properties. It will be extended with additional metadata properties, but something more open-ended is needed for both feed metadata and item metadata. One possibility is a new Feed Properties window and a new Item Properties window -- both along the lines of Outlook Express's Message Properties window. The General tab would provide fixed properties, some of which are editable, similar to the current Feed Properties window. The Details tab would provide a scrollable list of formatted, read-only (but copyable) metadata elements from the feed or an item. And a Source button will provide a text listing extracted from the feed's source.

Something else BF will eventually do with the metadata elements is to allow them to be included in complex queries through the Search Tool, but there is no UI proposal for this yet.