Ongoing discussions within the SWIM communities of interest

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Ongoing discussions within the SWIM communities of interest

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Task Status

This page is part of the ongoing SWIM communities of interest discussions. The content is working material. It should not be treated as final as it is still subject to review, comment and change.

This page helps the service architect combine multiple exchange models in one service payload.

Introduction

Most guidance assumes that the service architect will only need to consider the use of one exchange model when developing a service payload. However, SWIM allows services to be cross-domain. For example, a service may combine information from the aeronautical and weather information domains. This page therefore collects together advice on how to use the exchange models together,

Using AIXM and IWXXM

Problems

The following problem has been reported when there is an attempt to use AIXM and IWXXM in the same service.

In an attempt to combine information from the aeronautical and weather information domains, an XML schema (the root schema) was created that:

However, IWXXM itself imports a profile of AIXM (http://www.aixm.aero/schema/5.1.1_profiles/AIXM_WX/5.1.1b/AIXM_Features.xsd). The profile:

  • includes only a selection of AIXM features: AirportHeliport, Airspace, AirspaceVolume, AirspaceLayer, Runway, RunwayDirection, and Unit. However, the profile does not include all of a feature's properties.
  • uses the same namespace prefix (aixm) as the main AIXM.

This approach means that the selected features are defined in the full AIXM schema and in the profile with the same namespace prefix but with a different set of properties.

This means that some XML validators complain that the same feature is being redefined and this, in turn, makes the root schema invalid.

Potential work around

The simplest workaround is to equalise the two schemas. The service architect may:

  • import the IWXXM-AIXM profile into the root schema (replacing the import of the full AIXM 5.1.1)
    • this may mean the root schema no longer has the features required by the service
  • modify the IWXXM schema to make use of the full AIXM rather than the profile
    • this means that the IWXXM schema now allows many more properties than required
    • this means that the IWXXM schema has been modified by someone other than its owner

Another approach is to change the namespace:

  • modify the namespace used for the IWXXM-AIXM schema
    • this means that the IWXXM schema has been modified by someone other than its owner

Change request

Need for change request

All of the work around options can be performed by the service architect. However, each service architect may choose a different option. There is therefore a need to resolve this issue in the use of the AIXM profile within IWXXM.

A change request is in preparation to discuss this issue.







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