Schematron Validation for AQD

Transcription

1 Schematron Validation for AQD Complex Constraint Checking Barbara Magagna Katharina Schleidt

2 Overview AQD Constraint Checking Constraints within AQD e-reporting Schematron XML Schema Validation vs. Schematron Examples Check if element exists Check if element filled Check if element filled in dependency of other field Check if a code list entry is correct Check if the target of an internal xlink exists Conclusions 2

3 AQD Constraint Checking Project contract with JRC Tasks: 1. Check constraints of the AQD data model Logical constraints to be added to UML data model 2. Create and document Schematron rule files Schematron rules for constraints being produced 3. Conceptualize JRC Schematron web service JRC to provide online service to run Schematron rules 4. These rules will implement all possible rules from the QA checks document alignment of checks, these ones for the MS to be used inhouse, before uploading data to AQD Portal 5. Ongoing work to be finished asap 3

4 Constraints within AQD e-reporting Various types of constraints within AQD e-reporting: 1) Conditional fields (i.e. Element mandatory if traffic station) 2) Double use of classes with different cardinalities: a) AQD_SamplingPoint reused for Indicative Measurement b) AQD_Model reused for Expert Judgement 3) Correctness of code list entries 4) Target of xlink exists (i.e. Station available for SamplingPoint) 4

5 Schematron 1 Rule-based validation language Make assertions about the presence or absence of patterns in XML Structural schema language expressed in XML Simple basic syntax making use of: XPath XSLT XQuery Capable of expressing constraints in ways not possible with XML validation against XSD Logical Rule must be evaluated as TRUE, otherwise error Rules provide plain text explanations of the error found 5

6 Schematron 2 Schematron rule files can be transformed to XSLT for simple execution Various ways of executing Schematron Rules: Using XML Tools such as Oxygen (integrated) or XMLSpy (additional plugin required) Performing XSLT transformation locally XSLT transformation service will be provided by JRC Based on publicly available ISO Standard: ISO/IEC Document Schema Definition Languages (DSDL) Part 3: Rule-based validation - Schematron 6

7 XSD Validation vs. Schematron XSD Validation purely based on syntax: Class and element names defined Sequence of elements defined Cardinality of elements defined Valid even if element is empty Schematron Validation based on semantics: Define logical rules Logic can pertain to values of other elements or attributes Logic can include external files (i.e. code lists) 7

8 Examples - Check if element exists Requirement: Double use of classes with different cardinalities i.e. AQD_SamplingPoint reused for Indicative Measurement Example: aqd:aqd_samplingpoint/aqd:relevantemissions/aqd:relevantemissions Mandatory if aqd:aqd_samplingpoint/aqd:assessmenttype = Fixed measurement Optional if aqd:aqd_samplingpoint/aqd:assessmenttype = Indicative measurement Rule: (assessmenttype = Fixed measurement) AND (string-length($relevantemissions)>0) 8

9 Examples - Check if element filled Requirement: empty elements or attributes often valid to XSD i.e. <aqd:objectivetype xlink:href=""/> is valid Rule: ObjectiveType = aqd:aqd_samplingpoint/ aqd:environmentalobjective/aqd:environmentalobjective/ aqd:objectivetype/@xlink:href string-length($objectivetype)>0 9

10 Examples - Check if element filled in dependency of other field Requirement: Conditional fields i.e. KerbDistance element mandatory if traffic station Rule: EmissionSource = aqd:aqd_samplingpoint/aqd:relevantemissions/ aqd:relevantemissions/aqd:mainemissionsources/@xlink:href KerbDistance = aqd:aqd_sample/aqd:kerbdistance/text() (EmissionSource = Traffic) AND (stringlength($kerbdistance)>0) 10

11 Examples - Check if a code list entry is correct Requirement: codelist entry exists i.e. zonetype in codelist zonetype Rule: ZoneType = aqd:aqdzonetype/@xlink:href Codelist = document(' zonetype/rdf') $Codelist/rdf:RDF/skos:Concept[@rdf:about = $ZoneType] Note: uses XQuery, compares all code list entries (Xpath rdf:rdf/ skos:concept/@rdf:about) with the ZoneType from the XML data file 11

12 Examples - Check if the target of an internal xlink exists Requirement: check xlink i.e. Is content of reportingheader provided in file Rule: Content = aqd:aqd_reportingheader/aqd:content[1]/@xlink:href FeatureCollection = /gml:featurecollection $FeatureCollection/gml:featureMember/aqd:AQD_Attainment/ aqd:inspireid/base:identifier[base:localid = $Content] Note: uses XQuery, looks for inspireid matching content of ReportingHeader xlink in the entire XML file (FeatureCollection) 12

13 Conclusions Schematron makes up for the deficits of XML Schema validation against XSD Schematron defined in accordance with ISO Standards (ISO/IEC 19757) Rules for AQD e-reporting will be provided Execution possible as Schematron, XSLT, via JRC Service Documentation will be made available 13

14 Thank you for your attention Kathi Schleidt Barbara Magagna Data Management & Reporting Unit Umweltbundesamt GmbH Spittelauer Lände Vienna/Austria 14