The AIXM Rule Checker (ARC) is a proof-of-concept tool, based on open source Schematron technology, that implements the validation of the AIXM (version 4.5) Business Rules.

Schematron is a rule-based validation language for making assertions about the presence or absence of patterns in XML trees. Schematron is an ISO Standard: ISO/IEC 19757 - Document Schema Definition Languages (DSDL) - Part 3: Rule-based validation - Schematron.

The ARC tool provides a graphical interface for interacting with the Schematron rule checker for AIXM 4.5 files and for visualising the validation reports. ARC has been developed for EUROCONTROL by EGISAvia in the context of the “AICM Business rules review” study performed in 2006-2007.

This page contains information about the purpose of the AIXM business rules and provides the ARC proof-of-concept tool code for download.

What are AIXM "business rules"

The term "business rules" is used to designate other constraints on the data, than those which have been captured as features, attributes and relationships in a data model. This includes definition of attribute domains and their optionality; relationships cardinality, optionality and exclusivity; rules expressed in plain language.

The AIXM Conceptual Model (AICM) contains a number of plain language rules that define information constraints, which cannot be captured by other modelling means, such as:

		rules that check compliance with relevant (ICAO, ARINC 424, etc.) standards;
		rules meant to check data consistency;
		rules that impose minimal data availability;
		rules that test data plausibility;
		etc.

Examples of such rules in AICM 4.5:

		For every aerodrome/heliport there must be at least one postal address and one telephone number defined;
		All geographical coordinates should be expressed in the WGS 84 system;
		For an Airspace Vertex, If CODE_TYPE='CWA' or 'CCA', then the distance between the centre of the arc and the two ends (the one specified by the current vertex and the one specified by the next vertex) shall not differ by more than 1%;
		For a VOR, the value of the VAL_FREQ must be multiple of 50 kHz (e.g. 117.950 is a correct value while 117.975 is not);
		etc.

How AIXM business rules can be applied

Such plain text rules are not implemented in the AIXM schema (XSD). The primary reason is that the XML Schema (XSD) language is lacking capabilities for expressing such rules. A second reasons is that an AIXM-XML file validated against an XSD Schema is either valid or invalid. However, many plain text rules are not absolutely applicable to any data set and in any context. The best approach is to raise warning messages, indicating that some rules are not complied with. This can be the result of either a real error in the data chain or the result of the non-compliance of the real world feature with some business rules.

The AICM 4.5 business rules are typically verified when the data is input in a database. For example, the European AIS Database (EAD) tests the compliance of new data with such rules during the "private/public slot" checks. The results are reported back to the data provider in the form of messages classified as "errors" and "warnings". Most require a corrective action before being committed in the database.

Using Schematron, it is possible to test a stand-alone AIXM file against such rules. The ARC tools provides a graphical interface that facilitates the customisation of the validation through profiles, the execution of check and the visualisation of the reports. It does not diminish in any way the open standard character of Schematron.

How ARC-WEB can be used

The code for ARC-WEB is available below. Note that the ARC application is not linked at all to AIXM schema or structure. Of course the rules have been written only for AIXM4.5, but rules can be written for any other schema. The help file describes shortly the rule definition file format.

The application can work in two modes.

(1) Either as a standalone application for Windows and Internet Explorer. No installation is required in this case.
Just download and unzip the distribution on your local drive.

		ARC-WEB for Internet Explore (22 MB)
		ARC-WEB Sample Report (1.54 MB)

(2) Or as a web application. In that case, the server part is available for Windows and Linux.
The client can be Internet Explorer or Firefox. Installation instructions are included in the Zip file linked below.

ARC-WEB Server Installation (90 MB)

(3) The EGISAvia Web site also provides a demonstration of an ARC-WEB installation, where you can try it immediately.

ARC-WEB on EGISAvia Web site

Technical support

EUROCONTROL does not provide technical support for the use of ARC-WEB. It was developed as a proof-of-concept and as a test of the Schematron capabilities. All the documentation available and the source code are provided "as-is" on this Web site. It is hoped that this is sufficient for those who are interested to reuse this development. In case of further questions, please use the AIXM Forum. General Schematron support is also available from the Schematron community.

		Schematron explained by Wikipedia, the free encyclopedia
		The Schematron reference site
		Schematron Implementer's FAQ

Last validation: 30/07/2008

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