Page Table of Content

Requirement

Requirement [+]

Title	Information definition namespace
Identifier	SWIM-INFO-006
Requirement	An information definition shall declare a dedicated namespace for its concepts.
Rationale	A dedicated namespace is needed to disambiguate the content of one information definition from the content of another and from the content of the AIRM.
Verification	Completeness
Examples/Notes	Example: The namespace used in the Aeronautical Information Exchange Model is: “aixm:http://www.aixm.aero/schema/5.1”. Note: In the absence of a declared namespace, the namespace can be derived from the service that is described in a service description.
Level of Implementation	Mandatory

Guidance

A namespace is defined as "A set of elements in which each element has a name unique within that set. The same name may be associated with elements in different sets."

Guidance on namespaces are available at various locations such as https://en.wikipedia.org/wiki/XML_namespace.

The requirement talks about "a dedicated namespace". Dedicated is understood to mean that the namespace is unique and allocated to a particular set of names. This normally means that it is managed/governed by an organisation.

It is acceptable to have more than one namespace in an information definition. This reflects that some information definitions are large and spread over multiple files. In addition, many are organised around the idea of a "core" model and "extensions" - each of which may have its own namespace.

In many cases the namespace will be a URL that is stable over a long time. Ideally it should reference to an actual schema file but this is not always so.

The specification caters for the fact that information definitions are often contained in service descriptions. When no namespace is given for the information definition itself, it can be derived from the service. In effect, the service name acts as the namespace.

Verification Support

Completeness

Check that:

[ ] The information definition declares a dedicated namespace for its concepts.

Examples

XML Schema

The example below shows how the namespace can be embedded into an XML schema.

A complete example is available at: complete example.

Example of SWIM-INFO-006

xmlns:don="http://www.swim.donlon-airport.com/swim-ops/gateway" 
targetNamespace="http://www.swim.donlon-airport.com/swim-ops/gateway"

Spreadsheet

The spreadsheet available on the Example information definition page provides an example of where no dedicated namespace is provided. The name of the service (Donlon TOBT Setting Service) acts as the namespace in this case.

This example can be used by all non-machine readable formats for information definitions and service descriptions.

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