(This document is part of an effort to flesh out use cases for microdata inclusion in HTML5. See the original use case document, and the background material document as well as the email correspondence that best describes this process.)


Original Use Case: Search

USE CASE: Site owners want a way to provide enhanced search results to the
engines, so that an entry in the search results page is more than just a
bare link and snippet of text, and provides additional resources for users
straight on the search page without them having to click into the page and
discover those resources themselves.


* For example, in response to a query for a restaurant, a search engine
might want to have the result from provide additional
information, e.g. info on price, rating, and phone number, along with
links to reviews or photos of the restaurant.


* Information for the search engine should be on the same page as
information that would be shown to the user if the user visited the


The ability to add information into a web page that can enhance search reliability seems to have been mentioned in more than one communication. In addition, this enhanced search goes beyond just returning links to pages with the original material, but also includes the ability to provide relevant information directly in the search result, in addition to enabling smaller-scale aggregation of data for searching.

Generally, this capability is alluded to in several communications by Charles McCathieNevile, from the Opera Software, Standards Group, dated the beginning of January, 2009. I won’t repeat all of the information, but the text that seems most relevant to the use of metadata to enhance search capability include (but are not limited to):

There are many many small problems involving encoding arbitrary data in
pages – apparently at least enough to convince you that the data-*
attributes are worth incorporating.

There are many cases where being able to extract that data with a simple
toolkit from someone else’s content, or using someone else’s toolkit
without having to tell them about your data model, solves a local problem.
The data-* attributes, because they do not represent a formal model that
can be manipulated, are insufficient to enable sharing of tools which can
extract arbitrary modelled data.

RDF, in particular, also provides estabished ways of merging existing data
encoded in different existing schemata.

There are many cases where people build their own dataset and queries to
solve a local problem. As an example, Opera is not intersted in asking
Google to index data related to internal developer documents, and use it
to produce further documentation we need. However, we do automatically
extract various kinds of data from internal documents and re-use it. While
Opera does not in fact use the RDF toolstack for that process, there are
many other large companies and organisations who do, and who would benefit
from being able to use RDFa in that process.

I picked this quote because it effectively demonstrates the complexity of metadata enabled searching. This type of search is not just a matter of plunking any data into a web page and hoping it gets extracted by Google or Yahoo. Instead, metadata enriched searching annotates the data in such a way that the syntax is consistent and reliable, so that one only needs to generate one toolset in order to either produce the data, or extract it.

This is particularly essential for metadata enabled searching, because if the data is not based on the same underlying data model, the data cannot be merged into one store, nor can it be queried as one store at a later time.

Charles further emphasizes the importance of a consistent data model with the following:

Many people will be able to use standard tools which are part of their
existing infrastructure to manipulate important data. They will be able to
store that data in a visible form, in web pages. They will also be able to
present the data easily in a form that does not force them to lose
important semantics.

People will be able to build toolkits that allow for processing of data
from webpages without knowing, a priori, the data model used for that

And the following:

If the data model, or a part of it, is not explicit as in RDF but is
implicit in code made to treat it (as is the case with using scripts to
process things stored in arbitrarily named data-* attributes, and is also
the case in using undocumented or semi-documented XML formats, it requires
people to understand the code as well as the data model in order to use
the data. In a corporate situation where hundreds or tens of thousands of
people are required to work with the same data, this makes the data model
very fragile.

RDFa’s ability to add this search capability has been stripped out of the use case because it is considered an “implementation detail”. However, to the best of my knowledge, RDFa is the only specification that provides this capability, and for which there are actual implementations demonstrating its feasibility.

The RDFa-use-cases Wiki points to Search Monkey as an example of a Search Engine based more on extracting metadata encoded into a web page, than using some form of algorithmic alchemy.

There is also an excellent case study document at the W3C that discusses Search Monkey, and its relevance to enhancing search with metadata annotation.

Though actual implementations are not referenced in the use case document submitted by Ian Hickson, it’s important to note that such implementations do exist. Such actual implementations cast doubt on the assertions (in IRC at and elsewhere) that RDF is a failure, there are no web sites incorporating RDFa and so on.

Based on this, I would also recommend the following use case for this particular requirement:

I have a music store selling CDs, as well as original vinyl records, in addition to sheet music, posters, and other music memorabilia. I want to annotate my store listings with information such as artist name, song, and medium, as well as prices. I'm hoping this information will be picked up by search engines, and when someone is looking for something I'm selling, my store will popup, including information about the item for sale.

This information can be derived from natural language processing. However, I also want to record recommendations, so that people searching for something such as a poster of the Beatles' Abbey Road will not only see that I sell the Beatles' Abbey Road poster, but that I also sell a poster featuring the Yellow Submarine, and one featuring a photo of Mick Jagger from the early 1970's, as well as other British Invasion memorabilia.

When people click through to my site, not only do I list items for sale, but I also list other information, derived from sites such as Music Brainz, so that people not only associate my site with things to buy, but also a fun place to visit just to learn something new, and interesting.

Lastly, I want to provide a web service where people who review music can provide a link to their web feeds, also annotated with metadata, that I process with an application I downloaded, for associations relevant to music and artists I feature, so that i can include an excerpt of their reviews, and a link for the full review. With this approach, the web site owner doesn't have to remember to link directly between a specific review and an artist and song. And by using well-defined metadata I have access to pre-built tools so that I don't have to derive a complex natural language processing algorithm in order to pull out just the pertinent information in order to create a link between my store and the review.

Extrapolate from this use case to a store featuring squid art, another selling gourmet chocolate, a third jewelry made from recycled materials, and a travel agency, but with one stipulation: the businesses use the same basic toolsets, including content management system, and web services, as well as underlying data store.

This generic data model and toolset aren't arbitrary requirements: A generic data model ensures that one set of tools can have wide use, encouraging development of more tools. Generalizing the toolset ensures that the best are available to all of the stores, and that those people who may provide reviews of music and also funky jewelry, can use the same CMS, and the same underlying metadata structure, in order to annotate both to ensure inclusion of all reviews at relevant stores.

(Though not specifically related to the requirements process, a recent publication on the use of RDFa and music data can be found in the writing, Data interchange problems come in all sizes.)

HTML5 Photography

Pack of pictures and other stuff

I’ve put together a package of photos I’ve taken earlier this year. They include photos of places around town, flowers, chimps, and other critters. This is the package of photos I’m currently using for my screen saver, so I thought I’d put it online. I don’t guarantee you’ll like any of the pictures, but if you don’t, the most it will cost you is the download time. Note, the file is 17.3MB so I hope you have broadband. If you want to look at the photos online, they’re all at MissouriGreen.

I’m in the process of butting into the HTML5 effort in regards to RDFa. You can read the history of this effort at the HTML WG list. I’m taking the HTML5 editor, Ian Hickson’s, use cases, his original raw material, and mapping the two. I’m also adding in my own use cases. In the effort to make the use cases “implementation free”, I think that the detail and the complexity of the original use cases were reduced too drastically. You can see what I mean by my first use case, and will have the same for the others by Monday.

Will this make a difference? I haven’t a clue. Probably not. I’m sure that neither the HTML5 group, nor the RDFa group, appreciate my particular style of “contributing”, but I decided to follow Sam Ruby’s advice to “put up or shut up” when it comes to HTML5. I’m just going to put up or shut up in my way.

In the meantime, I need to return to my book, which also means that I will be tearing apart my sites as part of my research. I don’t expect to be twittering much, or writing to the weblog, either, in the next few months. I need to focus on the book, and other writing/work for income. I’m also really burned out and very tired, and feeling under the weather lately, and have a need to disconnect from the social hive. Emails always welcome, but I just don’t feel like “broadcasting”.

If you do access any one of the sites at any point in time and find them either not working, or working oddly, no worries, this is just me experimenting, researching, documenting, and writing. Hopefully by the time my book is done, I’ll be more up for writing to my web sites, and they’ll be all settled down and behaving.

If you do follow along with my RDFa use case efforts, I hope you’ll make comments at the HTML WG, as that’s the appropriate place to have a discussion. However, I will also open up comments for a week, in case you just want to make more casual remarks here. Or you can just ignore the whole thing, which is also a good option.



(This document is part of an effort to flesh out use cases for microdata inclusion in HTML5. See the original use case document, and the background material document as well as the email correspondence that best describes this process.)


USE CASE: Allow authors to annotate their documents to highlight the key
parts, e.g. as when a student highlights parts of a printed page, but in a
hypertext-aware fashion.


* Fred writes a page about Napoleon. He can highlight the word Napoleon
in a way that indicates to the reader that that is a person. Fred can
also annotate the page to indicate that Napoleon and France are
related concepts.


Ian has already provided his summary of this use case in the What WG group list. His summary

This use case isn’t altogether clear, but if the target audience of the
annotations is human readers (as opposed to machines and readers using
automated processing tools), then it seems like this is already possible
in a number of ways in HTML5.

In conclusion, this use case doesn’t seem to need any new changes to the

This use case was submitted by Kingsley Idehen, who said considerably more than was entered into the summary user case. Kingsley wrote:

When writing HTML (by hand or indirectly via a program) I want to
isolate at describe what the content is about in terms of people,
places, and other real-world things. I want to isolate “Napoleon” from a
paragraph or heading, and state that the aforementioned entity is: is
of type “Person” and he is associated with another entity “France”.

The use-case above is like taking a highlighter and making notes while
reading about “Napoleon”. This is what we all do when studying, but when
we were kids, we never actually shared that part of our endeavors since
it was typically the route to competitive advantage i.e., being top
student in the class.

What I state above is antithetical to the essence of the World Wide Web,
as vital infrastructure harnessing collective intelligence.

RDFa is about the ability to share what never used to be shared. It
provides a simple HTML friendly mechanism that enables Web Users or
Developers to describe things using the Entity-Attribute-Value approach
(or Subject, Predicate, Object) without the tedium associated with
RDF/XML (one of the other methods of making statements for the
underlying graph model that is RDF).

This use case could have used some more discussion between Ian and Kingsley, because, in my opinion, Ian’s interpretation doesn’t match what Kingsley wrote.

Kingsley wrote about annotating the information within the publication, as one would use a highlighter, but he didn’t mean that this information actually has to be highlighted and made visible to the person reading the text. I believe he meant that the annotation would be visible to processes that could then be made available, both to the individual who made the annotation (most likely at a later time, as notes), or perhaps others when aggregated (the latter is my own interpretation).

The question then, is there a mechanism currently in HTML5 where one can annotate the data within a writing, in a non-visible manner, and which one then be used to make an assertion, such as Napoleon is the name of a person, and the person Napoleon is related to another entity, this one named France (which is the name of a country, and so on).

So, let me take another try at this use case:

Within a writing published on the web, I want to add annotation into the text to highlight specific facts, but I don't want such highlighting to distract from the text, so I don't want it to be visible. An example of the type of annotation I may make is to highlight the word "Napoleon" and annotate this word with an assertion that Napoleon is a person, and to add further information, that the person, Napoleon, is related to France (a country).

I write on many topics, and so I may make use of several different vocabularies in order to perform my annotation. In addition, I may have to create my own vocabulary if the annotation I want to make doesn't match any of the known and previously published vocabularies. If I do, I'll do so in such a way that there can't be a possible conflict with any other vocabulary.

Once my text is documented, I want to be able to access this annotation at a later time, separate from the document. To do this, I'll process each of my writings with an application that will pull out this specialized annotation, for aggregation and later query. In addition, by using a standard metadata annotation technique and model, the data can also be accessed by search engines, making the data also available to others.

It would help to get concurrence from Kingsley as to the accuracy of my assessment, but I do feel comfortable that my use case is a closer approximation to what Kingsley meant. If this is so, Ian’s concluding statement about this use case, including the fact that it would require no change to HTML5 could be in error.