Reference data on the Web DEPUIS

Cover page
1 Introduction
2 Simple examples of reference data
3 Simple application using reference data

4 Lifecycle assessment for an individual house
A Lifecycle assessment ontology
B URI assigned to a thing by an ISO standard

2 Simple examples of reference data

2.1 Notation for the examples

Reference data is used to make statements. The simplest form of statement is a triple, as follows:

subject predicate (or verb) object

Hence we can say:

my cat sat on my mat

RDF (Resource Description Framework) defines a diagramatic form for triples. The example as RDF is shown in Figure 1.

A triple

Figure 1: A triple

In RDF, the subject, predicate and object are each identified by a URI. If the URIs are:

then RDF also defines an XML serialisation as follows:

<rdf:Description rdf:about="http://myThings.org/somePath/MyCat">
 <http://myVocabulary.org/somePath/satOn
            rdf:resource="http://myThings.org/somePath/MyMat"/>
</rdf:Description>

Although this is easily process by a computer, this is not easy for a person to read. Fortunately there is a simple alternative - N3. Using this alternative, the URIs for the subject, predicate and object are separated by spaces, and the statement (or sentence) is terminated with a full stop. Hence in N3 the statement becomes:

http://myThings.org/somePath/MyCat
        http://myVocabulary.org/somePath/satOn
                 http://myThings.org/somePath/MyMat .

The common text can be separated out as a prefix, giving the readable representation:

@prefix        myThing:              .
@prefix        myVocabulary:         .

myThing:MyCat  myVocabulary:satOn  myThing:MyMat  .

The notation has two useful abbrevations, as follow:

The notation also has "Bells and whistles". Two of the most useful are as follows:

N3 is used for most examples in this document. Occasionally, RDF serialised as XML is shown as well for clarity.

2.2 Type of a product

The type (or class) of thing "heat exchanger" is defined by ISO/TS 15926-4. At present, the standard merely defines the text label, and provides a definition.

For this to be useful as computerised reference data, two things have to happen:

The current proposal is that each of the following URIs will be assigned to heat exchanger:

This proposal give a person-interpretable or non-person interpretable URI as either a URN or an HTTP URI (formerly called a URL).

ISO TC184/SC4 may provide a representation of the HTTP URIs, so that if you access them by an HTTP GET (i.e. go there using a Web browser), then some useful information formated as an HTML document is retrieved.

The information provided by ISO TC184/SC4 will probably be limited to the definition. It is not the business of ISO TC184/SC4 to provide web services which add value to international standards.

However, a trade association "South Asian Association of Process Equipment Manufacturers" (say), is free to provide a resolver which returns much more useful information including links to suppliers. This resolver could implement HTTP URIs of the form:

It is important that when a supplier of good and services uses reference data to provide information to their customers, that information about the reference data is available on the Web in a convenient form and free of charge.

The simplest use of URI for a type of product, is to record the type of an individual product. If the individual product with URI http://www.f_bloggs.co.uk/products/07-1234 is a heat exchanger, then this can be recorded using N3 as follows:

http://www.f_bloggs.co.uk/products/07-1234
                 a  urn:iso:std:iso:ts:15926:-4:tech:rdl:HeatExchanger  .

The fragment of N3 shown above, may be part of larger RDF graph of design information with URI http://www.f_bloggs.co.uk/products/07-1234/design.

The assignment of an HTTP URI to each product manufactured by Fred Bloggs and Co. also has other benefits. For example the maintenance history may be held by a web service with URI http://www.f_bloggs.co.uk/products/07-1234/maintenance.

Information about a product may be contained on an RFID chip fixed to the product. In this case, the link between the RDID chip and the product to which it is fixed can be recorded by the vocabulary:

Using this vocabulary, the content of the RFID chip attached to the heat exchanger is:

<>  a          xxx:RFID ;
    xxx:partOf [ :-  http://www.f_bloggs.co.uk/products/07-1234
                 a   urn:iso:std:iso:ts:15926:-4:tech:rdl:HeatExchanger ] .

2.3 Location on a map

The mapping grid for the UK is defined by the "Ordnance Survey of Great Britain", and 100 metre squares within Great Britain have a "grid reference". Unfortunately the Ordnance Survey does not allocate a URI to a grid reference.

An approach which could have been adopted, and may be in the future, would be to allocate a URN to a grid reference, such as:

and to provide a public resolver on the Web, so that a map including the 100 metre square is returned by HTTP (web browser) access to:

Unfortunately, the Ordnance Survey has not done this. Instead the Ordnance Survey has provided the HTTP URI http://getamap.ordnancesurvey.co.uk/getamap/frames.htm. You have to go to this location, and type in "TQ123456".

Google maps is more useful for automated access because it assigns to a map around latitude 51.357079 north, 0.392547 west, the HTTP URI: http://maps.google.co.uk/maps?ll=51.197902,-0.392547.

The Ordnance Survey provides a better map, and a more convenient way of refering to a location. However few people use the Ordnance Survey facilities because they do not have a good Web interface. The Ordnance Survey has a business model which precludes giving out information over the Web. This will fail in the 21st century.

2.4 Postcode

Sets of neighbouring premises in the UK are defined by the "Royal Mail" and identified by a "postcode". Unfortunately the Royal Mail does not allocate a URI to a postcode.

An approach which could have been adopted, and may be in the future, would be to allocate a URN to a postcode, such as:

and to provide a public resolver on the Web, so that the list of premises with the postcode is returned by HTTP (web browser) access to:

Unfortunately, the Royal Mail has not done this. Instead the Royal Mail has provided the HTTP URI http://www.royalmail.com/portal/rm/addressfinder. You have to go to this location, and type in "SE12 0BS".

Google maps is more useful for automated access to postcodes, because it assigns to the region around SE12 0BS, the HTTP URI: http://maps.google.co.uk/maps?&geocode=&q=SE12+0BS.

The Royal Mail a business model which precludes giving out information over the Web. This will fail in the 21st century.



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