Introduction

The Service Orientation Process outlines the activities that are undertaken during the development of a service. 

For example, service architects will:

• design the service payload (the logical representation of the information exchanged by the service interface operations) based on the identified information exchange requirements (IER).
• later, a selection or definition of the data format will occur.

One of the key decisions becomes where to start in the design and what to implement. For example, it is possible to:

• use an existing information exchange model such as AIXM or FIXM.
• develop a new model or expose a proprietary model
• derive a model from the AIRM

Decision tree

The following diagram outlines some questions to be taken into account.

Use an information exchange model

Does an existing information exchange model fully meet the information exchange requirements (IER) that the service seeks to satisfy?

Existing standardised information exchange models include:

• Aeronautical Information Exchange Model (AIXM)
• Flight Information Exchange Model (FIXM)
• Weather Information Exchange Model (WXXM)
• ICAO Meteorological Information Exchange Model (IWXXM)
• Aerodrome Mapping Exchange Model (AMXM)

They are agreed and published by a particular community of interest. There may be multiple versions of an exchange model e.g. IWXXM 1.1 was used by the SESAR programme but a v2.1 is now available and v3 is in pre-operations.

The exchange models listed above relate to three ICAO business domains (aeronautical, weather and flight information).

If the chosen exchange model (or models) is sufficient, the information service payload can be defined based on it.

Should the existing exchange model be amended to fully meet the information exchange requirements (IER)?

An extension/modification may be needed when there is a gap in the information exchange model. An extension/modification may be desirable (e.g. instead of making a new model) based on a number of criteria such as:

• client requirements. It could be that the service consumers are already using the information exchange model.
• convenience. The service provider already has knowledge of the information exchange model and it is good to build upon the experience.
• the information to be exchanged is in the scope of the information exchange model and a modification to it makes sense.

If the decision is to amend the exchange model, the applicable processes will need to be followed.

Use the AIRM

If no existing information exchange model is found to be appropriate and no extension/modification is possible, the decision becomes whether to use a new model (or expose a proprietary model) or derive from the AIRM.

Use a new/proprietary model

It is, of course, possible to create a new model or expose a proprietary model. The service/information architect should take care to ensure that the requirements of the EUROCONTROL Specification for SWIM Information Definition are met.