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[DPF] Tree or Graph?

From: Keith Waters <kwaters@ftrd.us>
Date: Mon, 6 Jun 2005 12:03:58 -0400
Message-Id: <FAB1C2DA-3251-4750-B6C8-44842488A9E9@ftrd.us>
To: www-di@w3.org

Hi Jeremy and Mark,

This message contains a response to comments on

http://www.w3.org/TR/2004/WD-DPF-20041122/

Tree or Graph?

I am currently using a Microsoft Windows OS, it gives me a tree like  
view of my computer hardware, under the device manager. I can choose  
between two views of the devices Devices by type Devices by Connection

My understanding is that when I look at the properties of my DVD  
drive it is the same drive whether it's parent is a USB Mass Storage  
device whose parent is the USB Hub, or if its parent is DVD/CD-ROM  
drives whose parent is my computer.

So I am presented with two different trees whose leaf nodes are the  
same sets.

This seems to be a highly desirable feature if the goal is to allow  
different applications integrating devices from different  
manufacturers, since the different people involved with the  
development of the various applications and devices will have  
different views of the world. These different views will be reflected  
in different choices about how to structure their representation of  
the world, yet ... some of the concepts being used are the same and  
do represent the same devices.

We note that even in the more tightly controlled world of a Microsoft  
OS it is helpful to have multiple views.

In the XML world, it is natural to try to describe the world using  
tree like views. However, as RDF is a graph, it is possible to have a  
flexible representation where leaf nodes can be reached by multiple  
routes, accomodating different views of the world. Being able to  
accomodate such multiple views may be important as the goal here is  
to allow different applications integrating devices from different  
manufacturers. These different views will be reflected in different  
choices about how to structure their representation of the world,  
yet ... some of the concepts being used are the same and do represent  
the same devices.

RDF also stresses the idea that such representations should be  
designed from a semantic, rather than a syntatic viewpoint, and uses  
URIs to unambiguously identify subjects and properties. This approach  
should be used when designing representations in DPF.

Specifically DPF can gain some of these advantages if two small  
changes are made to DPFProperty: - permit multiple parents (not  
simply one or zero) - add a label, either a URI or a locally scoped  
identifier which identifies the instance which is the value of this  
property (when no literal value, string or other is given)


The DPF Working Group agree. The DPF is represented as a tree.

-Keith Waters
Received on Monday, 6 June 2005 21:55:46 GMT

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