GoodRelations: ProductOrService and its subclasses

Dear all:

I thought it was helpful to clarify the usage of the four classes for 
products and services in GoodRelations:

The intended usage is as follows:

    * ProductOrServicesSomeInstancesPlaceholder
          o Use this when you have multiple, mass produced items for 
sale. It represents multiple copies / individuals of the same kind.
          o This is the most frequently needed class. Also, use this for 
any service offers.
          o You can attach an inventory level to that instance in order 
to communicate how many items you are speaking of.
          o A typical Web shop will use this class for all items, unless 
you are selling very unique stuff (antiques, oldtimers, ...)

    * ActualProductOrServiceInstance:
          o Use this for eBay auctions, private offers of used goods, 
etc. - whenever your are offering a single, clearly identified object.
          o When you can attach a single serial number to the good your 
are offering, use this class.

    * ProductOrServiceModel
          o This class represents "datasheets" - the abstract template 
for mass-produced products.
          o If you are a manufacturer, use this class for each of your 
products.

    * ProductOrService
          o This is the superclass of all three other classes.
          o The only usage of this class is for defining specific 
vocabularies (ontologies) for vertical industries. All those must be 
subclasses of this class.
          o See 
http://www.ebusiness-unibw.org/wiki/Own_GoodRelations_Vocabularies

Remarks:

    * A gr:Offering can only be linked to instances of 
ProductOrServicesSomeInstancesPlaceholder or ActualProductOrServiceInstance.
    * Don't reuse someone else's 
ProductOrServicesSomeInstancesPlaceholder else. For example, the current 
BookMashup application wrongly uses the same instance for multiple 
vendors' offers.
But they are not referring to the same set of objects - they each have 
individual items. So always define a new instance of this class in your 
own namespace!

See the GoodRelations Primer, section 5.2 for more details:

http://www.heppnetz.de/projects/goodrelations/primer/
http://www.heppnetz.de/projects/goodrelations/primer/#5.2_Products_and_Services:_Models.2C_Classes.2C_and_Instances

Best
Martin Hepp

--------------------------------------------------------------
martin hepp
e-business & web science research group
universitaet der bundeswehr muenchen

e-mail:  hepp@ebusiness-unibw.org
phone:   +49-(0)89-6004-4217
fax:     +49-(0)89-6004-4620
www:     http://www.unibw.de/ebusiness/ (group)
         http://www.heppnetz.de/ (personal)
skype:   mfhepp 
twitter: mfhepp

Check out GoodRelations for E-Commerce on the Web of Linked Data!
=================================================================

Webcast:
http://www.heppnetz.de/projects/goodrelations/webcast/

Recipe for Yahoo SearchMonkey:
http://www.ebusiness-unibw.org/wiki/GoodRelations_and_Yahoo_SearchMonkey

Talk at the Semantic Technology Conference 2009: 
"Semantic Web-based E-Commerce: The GoodRelations Ontology"
http://www.slideshare.net/mhepp/semantic-webbased-ecommerce-the-goodrelations-ontology-1535287

Overview article on Semantic Universe:
http://www.semanticuniverse.com/articles-semantic-web-based-e-commerce-webmasters-get-ready.html

Project page:
http://purl.org/goodrelations/

Resources for developers:
http://www.ebusiness-unibw.org/wiki/GoodRelations

Tutorial materials:
CEC'09 2009 Tutorial: The Web of Data for E-Commerce: A Hands-on Introduction to the GoodRelations Ontology, RDFa, and Yahoo! SearchMonkey 
http://www.ebusiness-unibw.org/wiki/Web_of_Data_for_E-Commerce_Tutorial_IEEE_CEC%2709