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Subject: OGC Definition of Profiles
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
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