OGC Definition of Profiles

[Rex Brooks <rexb@starbourne.com>]

Hi Folks,

I have been continuing my research into how various groups have 
defined profiles, and I am copying here a section from the Open 
Geospatial Consortium Geography Markup Language GML 3.1. I'm not 
suggesting anything at this point. I'm just sharing my research. If 
anyone actually has access to technical report "ISO/IEC TR 
10000-1:1998 Information technology - Framework and taxonomy of 
International Standardized Profiles - Part 1: General principles and 
documentation framework" and can look at it, that might be helpful.

I turned to OGC because I recalled Dr. Carl Reed mentioning that they 
had a definition for their use of "Profile," and I wanted to check it 
out.

Cheers,
Rex

22 Profiles

22.1 Profiles of GML and application schemas
GML is a complex specification that is richly expressive. In general, 
an application need not exploit the entire specification, but may 
employ a subset of constructs corresponding to specific relevant 
requirements.

Quoting from technical report "ISO/IEC TR 10000-1:1998 Information 
technology - Framework and taxonomy of International Standardized 
Profiles - Part 1: General principles and documentation framework", 
we use this definition of a profile:

Profile: A set of one or more base standards and/or [profiles], and, 
where applicable, the identification of chosen classes [(types, 
attributes and elements)], conforming subsets, options and parameters 
of those base standards, or [profiles] necessary to accomplish a 
particular function.

Of course, this was defined for an OSI architecture model, so we must 
translate 'class' to 'types, attributes and elements' to apply this 
definition to XML Schema. There are several ways to implements this, 
and GML profiles uses a "copy and delete" approach. To create a 
profile, a developer might copy the applicable schema files from GML 
and simply delete any global types, elements and local optional 
particles that she does not need for her application schema.

22.2 Definition of Profile

A profile of GML can be defined to enhance interoperability and to 
curtail ambiguity by allowing only a specific subset of GML. 
Application schemas can then conform to such a profile in order to 
take advantage of any interoperability or performance advantages that 
it offers in comparison with a complete GML. Such profiles can be 
defined for application schemas that are included in other OGC 
specifications.

There are cases where reduced functionality is acceptable, or where 
processing requirements compel use of a logical subset of GML. For 
example, applications that do not need to handle XLink attributes in 
any form can adhere to a specific profile that excludes them; the 
constraint in this case would be to not use links. Other cases might 
include defining constraints on the level of nesting allowed inside 
tags (i.e. tree depth), or only allowing features with homogeneous 
properties as members of a feature collection. In many cases, such 
constraints can be enforced via new schemas; others may be enforced 
through procedural agreements within an information community.
-- 
Rex Brooks
President, CEO
Starbourne Communications Design
GeoAddress: 1361-A Addison
Berkeley, CA 94702
Tel: 510-898-0670