RE: Profiles - what do we mean by the term?

During the call today, the term "profile" was used numerous times. I am not 
sure we all have a common understanding by what we mean by a "profile". In ISO 
and the OGC, we use the following definition:

 

A 
profile is a strict subset of a Standard applicable to multiple 
Application Schemas. This is from ISO 19109 and is typically used in the context 
of XML schema.

 

If 
we use this definition, then a profile of CAP, or EDXL for that matter, would be 
a subset - not an extension, optional or otherwise. I am not sure that this is 
what we want. As soon as a group adds elements or changes the meaning of an 
existing element to meet local conditions, this is NOT a profile!

 

I 
think that several of us have been talking about is the concept of an extension. 
In the OGC, we have been having a strong dialogue about a general pattern for 
the development of all OGC standards. We call this model core-extension. 
Sometime in 2008, the membership will approve this pattern as policy to be used 
in the development of all OGC standards. 

 

Essentially 
what this means is that for most any standard (interface, payload, etc) it is 
possible to define a core set of elements/functionality that has an associated 
set of conformance clauses. The standard also provides guidance as to how to 
define extensions. Extensions allow for adding new elements or functionality - 
they do not break the core. This means that any organization implementing the 
core can achieve a desired level of interoperability and feel very 
confident that the core standard will not change much over a fairly long period 
of time. At the same time, extensions can be developed the enable the use of the 
core in other information domains, communities, programs, regions, and so forth 
- again without any modifications to the core. Further, extensions need not go 
through a standards organization for approval - unless the group that developed 
the extension wants to go to the effort.

 

Now, 
for a standard that is already in use and implemented, there may be some 
modification required to the existing standard (core) in order to enable the 
ability to define extensions. We already have some of this capability to define 
extensions in EDXL-RM and perhaps in DE but I am not familiar enough with 
DE.

 

So, 
in a way, I see the evolution of CAP using the core-extension design 
pattern as potentially a very positive move. CAP as we know it may stay pretty 
much as is: relatively simple, fairly easy to implement, and meeting specific 
requirements in a well defined community.  However, we may also be 
able to define a consistent approach to enabling extensions that allow for such 
capabilities as the specification of alternate coordinate reference systems, 
multiple coordinate reference systems, additional geometries, multiple 
geometries, time, and so forth. Such an approach protects current investment, 
future proofs the core standard, allows more communities to engage and use the 
standard. The list of benefits is quite long and very well 
documented.

 

I 
am not trying to fan any fires here. And I definitely do not develop standards 
for standards sake! I spent 25 years as a software engineer, lead design 
engineer, and then chief architect for a number commercial GIS products 
before joining the OGC. I am very pragmatic about how we develop and use 
standards.

 

Time 
to go watch House.

 

Cheers

 

Carl Reed, PhD
CTO and Executive Director Specification 
Program
OGC

 

The OGC: Helping the World to Communicate Geographically

 

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