1. IVOA Registry videocon 2004/05/13-14 Gerard Lemson1 Model based schema

2. IVOA Registry videocon 2004/05/13-14 Gerard Lemson2 UML to XSD binding Start with UML model Generate XMI from UML Define UML to XSD binding Implement binding as XSLT script Run script

3. IVOA Registry videocon 2004/05/13-14 Gerard Lemson3 Sample UML

4. IVOA Registry videocon 2004/05/13-14 Gerard Lemson4 Mapping “methodology” Simple: as “1-1” as possible Preserve semantics –Attributes owned by class –Children in parent-child composition relation owned by parent/container Focus on type definitions, complexType-s mainly Valid documents (global elements) defined with respect to, but separate from the type definitions Default document: contains an element definition under the root for each “root-entity-class”. Possibility of reuse of schema type definitions in different special purpose document definitions.

5. IVOA Registry videocon 2004/05/13-14 Gerard Lemson5 Mapping: packages Package -> (target)namespace, in own file Dependency -> import of dependent namespace and file <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="urn://xml.registry.gavo.org/aas" elementFormDefault="qualified" attributeFormDefault="unqualified" version="0.1" xmlns:aas="urn://xml.domainmodel.gavo.org/aas" xmlns:base="urn://xml.domainmodel.gavo.org/" xmlns:cees="urn://xml.domainmodel.gavo.org/cees">... <xsd:import namespace="urn://xml.registry.gavo.org/cees" schemaLocation="./cees.xsd" />

6. IVOA Registry videocon 2004/05/13-14 Gerard Lemson6 Mapping Classes Every class -> globally defined complexType isAbstract -> abstract=“true” Attribute -> element of simplish-type, either built-in, or also generated

7. IVOA Registry videocon 2004/05/13-14 Gerard Lemson7 Mapping Classes II Inheritance -> extension of base class

8. IVOA Registry videocon 2004/05/13-14 Gerard Lemson8 Mapping Associations I Parent-child relationship Composition -> element of appropriate complexType <xsd:element name="dees" type="cees:D" minOccurs="0" maxOccurs="unbounded" />

9. IVOA Registry videocon 2004/05/13-14 Gerard Lemson9 Mapping associations II “Owned references” -> element of appropriate type

10. IVOA Registry videocon 2004/05/13-14 Gerard Lemson10 Mapping associations III Problem: shared references (also aggregations), many-to-1/many relations Does one want to replicate elements that are shared ? Multiple B-s can reference same C. Solutions: –Don‘t care, map ala composition, with cardinality maxOccurs=“0” –Use ID/IDREF or KEY/KEYREF declarations. Requires the C to exist in same document, possibly completely, i.e. containing all substructure. –Use explicit “proxy ” element, for example using a GUID (IVOA identifier?), which can/must be resolved before the referenced object can be obtained. This is the most tricky thing I think about XML schemas, how to properly embed the semantics of the shared association into a logical schema design.

11. IVOA Registry videocon 2004/05/13-14 Gerard Lemson11 Default Document Root entity classes map also to an element in a document, but in a separate schema doc, depending on the type defining schema documents. <xsd:schema targetNamespace="urn://xml.registry.gavo.org/doc"... xmlns:doc="urn://xml.registry.gavo.org/doc" xmlns:cees="urn://xml.registry.gavo.org/cees" xmlns:aas="urn://xml.registry.gavo.org/aas"> <xsd:import namespace="urn://xml.registry.gavo.org/cees" schemaLocation="./cees.xsd" /> <xsd:import namespace="urn://xml.registry.gavo.org/aas" schemaLocation="./aas.xsd" /> <xsd:element name="c" type="cees:C" minOccurs="0" maxOccurs="unbounded" /> <xsd:element name="a" type="aas:A" minOccurs="0" maxOccurs="unbounded"/> <xsd:element name="b" type="aas:B" minOccurs="0" maxOccurs="unbounded"/>

12. IVOA Registry videocon 2004/05/13-14 Gerard Lemson12 Comments Single inheritance mapping, only extension, no substitutionGroup Requires xsi:type construct (next slide) to indicate which precise class is used. No element ref construct. No global elements for attributes and contained classes. Analogy to Java binding : –Complex type class –Typed declarations Fields in class definition –Default document a main method using the classes. –Global elements variable declarations local to main method Can support a more involved special purpose document to/from the “official” default registry document using XSLT scripts for example (view concept). See also: http://www.xml.com/pub/a/2002/08/07/wxs_uml.html and othershttp://www.xml.com/pub/a/2002/08/07/wxs_uml.html Probably more …

13. IVOA Registry videocon 2004/05/13-14 Gerard Lemson13 xsi:type xsi:type=‘’ construct from the xmlns:xsi=“http://www.w3.org/2001/XMLSchema-instance” in document required to indicate precise class: <doc:sample xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:doc="urn://xml.registry.gavo.org/doc" xmlns:cees="urn://xml.registry.gavo.org/cees"> a C a D1 a D2