W3C home > Mailing lists > Public > public-vocabs@w3.org > December 2011

Re: ItemAvailability DateChanged Instance

From: Martin Hepp <martin.hepp@ebusiness-unibw.org>
Date: Wed, 14 Dec 2011 22:00:23 +0100
Cc: public-vocabs@w3.org
Message-Id: <D52939A1-0483-47F7-A673-064FF2CF775F@ebusiness-unibw.org>
To: Ryan Berger <berger82@gmail.com>
Hi Ryan,

basically, the search engine can use the HTTP header information as a good proxy. All you would need to do is make sure that the server returns the correct last modification date for an item page:

curl -I <URI>

HTTP/1.1 200 OK
Date: Wed, 14 Dec 2011 20:53:20 GMT
Server: Apache
Last-Modified: Thu, 27 Jan 2011 14:08:27 GMT


Overstock, e.g. does not return this, but it would make life easier for crawlers and all kinds of HTTP clients:

curl -I http://www.overstock.com/Home-Garden/Comfort-Dreams-Select-A-Firmness-11-inch-Queen-size-Memory-Foam-Mattress/3158654/product.html?IID=prod3158654&sec_iid=74104
[1] 29485
HTTP/1.1 200 OK
Date: Wed, 14 Dec 2011 20:52:18 GMT
Server: Apache
Set-Cookie: <omitted>
Expires: Wed, 14 Dec 2011 20:52:18 GMT
Pragma: no-cache
Keep-Alive: timeout=15, max=100
Connection: Keep-Alive
Encoding: iso-8859-1
Content-Length: 270336
Vary: Accept-Encoding,User-Agent
Cache-Control: no-cache, no-store
Content-Type: text/html;charset=iso-8859-1

You can also combine more granular GoodRelations elements with schema.org, as announced at the last schema.org workshop in SFO.

E.g. by attaching the gr:hasInventoryLevel property to http://schema.org/Offer:

	<div itemprop="offers" itemscope itemtype="http://schema.org/Offer">	
    	<meta itemprop="priceCurrency" content="USD">$
 		<span itemprop="price">55.00</span>
		<time itemprop="priceValidUntil" datetime="2012-12-31">(Valid through Dec 31, 2012)</time>
    	Availability: <link itemprop="availability" href="http://schema.org/InStock" />In stock
<!-- inventory level -->
  		Items on stock: <span itemprop="http://purl.org/goodrelations/v1#hasInventoryLevel" itemscope
    		<meta itemprop="hasMinValue" content="7">

This works, as you can see here


The Google Testing Tool still issues warnings for these additional signals, but it has been communicated by the schema.org sponsors that this will be fixed in the future. So from my experience I would say you can use is immediately.


Martin Hepp

On Dec 14, 2011, at 8:33 AM, Ryan Berger wrote:

> In addition to the existing Instances of ItemAvailability (Thing>Intangible>Enumeration>ItemAvailability, which includes InStock, OutOfStock, PreOrder and so-on), it would be nice to have the option to indicate a date when the ItemAvailability changed. 
> If Search Engines understood Offer A has been OutOfStock since 2009-11-11 and Offer B (a similar product with less history) has been InStock since 2011-11-11, they could tailor better results to informational versus transactional queries. 
> Ryan Berger 
Received on Wednesday, 14 December 2011 21:00:59 UTC

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