The document discusses the generation of XML schemas from a canonical model, focusing on the use of PowerDesigner for managing XML schemas. It emphasizes the flexibility of PowerDesigner in creating, editing, and maintaining XML schema models, and highlights the need for a hierarchical master schema to ensure consistency. Additionally, it addresses challenges in generating individual schemas and managing multiple reference models effectively.

1. Generating XML Schemas from a canonical model - a practical exampleGeorge McGeachieMetadata Matters LimitedEnterprise Data WorldChicagoApril 5th, 2010

2. The ‘C’ wordManaging XSDs using a master (canonical) XML schemaThe flexibility of PowerDesignerThe XML Schema Model in PowerDesignerWhich Canonical Model Should You Use?Factors To Be ConsideredGenerating XML Models in Power DesignerEnterprise Data World, Chicago, April 5th 20112

3. About MeI’ve been involved with modelling and managing data and metadata for longer than I care to remember.When I first came across XML Schemas, I was struck by their simplicity and versatility. When I saw how some people use them, I realised that the days of unmanaged COBOL copybooks had returned to haunt me.This is my attempt to exorcise the XML demon.Enterprise Data World, Chicago, April 5th 20113

4. The ‘C’ wordIt’s difficult to avoid the word ‘Canonical’ when discussing standard XML messagesTo some, the message schemas are the ‘canonical’To others, the underlying model is the ‘canonical’When I use the word, I mean both of themEnterprise Data World, Chicago, April 5th 20114

5. Managing XSDs using a master (canonical) XML schemaAn XML master schema must be hierarchicalIt cannot easily show all the complex relationships between the data conceptsIt cannot be flexible enough to support multiple views of the dataYou need to understand XML to create, edit or read the modelEnterprise Data World, Chicago, April 5th 20115

6. Managing XSDs using a master (canonical) XML schemaHow would we integrate the metadata represented by a schema with our other metadata?Reverse-engineer it into a repository or modelling tool?How would weEnsure consistency of XSDs with each other?Enable impact analysis?Manage the variations necessary between dependent schemas?Enterprise Data World, Chicago, April 5th 20116

7. The flexibility of PowerDesignerEnterprise Data World, Chicago, April 5th 20117PowerDesigner has a dedicated XML Schema ModelSeveral different approaches supported out of the boxGenerating XSDs from a class modelGenerating an XML Schema model from a class model or a physical data model, then generating XSDsReverse-engineering existing XML Schemas into a class model or XML Schema ModelCan then generate a logical or conceptual view

8. Generation options in PowerDesignerEnterprise Data World, Chicago, April 5th 20118

9. The XML Schema Model in PowerDesignerEnterprise Data World, Chicago, April 5th 20119This can link to an XML model, or an XSDReferencedElements (in another XSD)Complex TypeNote the XML-specific object types

10. XML-specific Model Objects10Enterprise Data World, Chicago, April 5th 2011Here’s the detail of one of the sequences in the schemaFilter the displayed propertiesAdd additional items to the sequence

11. The XML ModelDedicated to modelling XML Schema1 schema per XML model, traceable to source modelsMapping Editor – drag and drop mappings between modelsSupports XSD, XDR and DTDMultiple Namespaces supportedCan use 1 XML model for multiple schemas in the same target namespaceEnterprise Data World, Chicago, April 5th 201111

12. The flexibility of PowerDesignerLinkages are automatically maintained between models as you generate themAdditional mappings can be added between any two modelsThe generation process can be customisedYou have control over the naming standards and data types used in each modelImpact and Lineage analysis is enabled by the generation and mapping linksEnterprise Data World, Chicago, April 5th 201112

13. Generation LinksFor each model, you can trace links to other models in the generation sequenceEnterprise Data World, Chicago, April 5th 201113

14. Mapping EditorVisually check mappingsEnterprise Data World, Chicago, April 5th 201114

15. Impact of deleting XML Attribute - diagramEnterprise Data World, Chicago, April 5th 201115Dependencies between PDM tablesPDM Tables mapped to the ElementOur attributeXML ElementSimple Type (no longer required)Remember: this diagram traces back to the model the XML attribute was generated from; in this case, the XML model was generated from a PDM, so the impact analysis traces to the PDM

16. Visible Links Between ModelsUsing the ‘project’ feature, we can see the links between modelsWe can also include external objects, and create our own links to themAn XSD and an HTML file in this caseEnterprise Data World, Chicago, April 5th 201116

17. Which canonical model?One (or more) that you can sell within your organisationStandard modelsStandard Universal Data Modelse.g. IBM, Teradata, Oracle, EWS Solutions, Len Silverston’s Universal Data ModelsIndustry Universal Data Modelse.g. standard messaging structures, such as from the OAGSee www.industrydatamodels.com Some organisations use several of these, which will need to be cross-referencedYour own model(s)possibly used to extend one of the aboveEnterprise Data World, Chicago, April 5th 201117

18. A simple example of a relational canonical modelEnterprise Data World, Chicago, April 5th 201118This is an amended version of the ‘Project Management’ PDM supplied with PowerDesigner

19. The ‘Team Members’ schemaEnterprise Data World, Chicago, April 5th 201119

20. The ‘Project’ schemaEnterprise Data World, Chicago, April 5th 201120

21. Factors To Be ConsideredGenerating a Type Library vs. generating SchemasPhysical Design ChallengesModel Management Challenges21Enterprise Data World, Chicago, April 5th 2011

22. Generating a type libraryoften straightforward to generateno structuremanual control of re-use in schemas"let the service people design the schemas"no impact analysis across schemasmay be the only acceptable first steplow impact on work patternsgains initial acceptance of the role of a canonical modelEnterprise Data World, Chicago, April 5th 201122

23. Generating Individual SchemasA 'container' for each schemaModel, Submodel, Subject Area, Package etcdefines scopeprovides documentationfacilitates governanceComplete generationNothing changed post-generationRequires high degree of control over generation processEnterprise Data World, Chicago, April 5th 201123

24. Generating Individual Schemasall types can be localno need to 'include' or 'import' a base schemathe 'standard' types are used to generate the schema, rather than being referred to by the schemaThe standard types are in the canonical data modelpotential for impact analysiscan choose when to update each individual schemaEnterprise Data World, Chicago, April 5th 201124

25. Sample Message SchemaThis was generated from the same data model as the type library; it only contains what the message actually needsEnterprise Data World, Chicago, April 5th 201125

26. Physical Design ChallengesSome of these challenges are similar to those we face when we use a single Logical Data Model for designing multiple database schemasDifferences between SchemasHandling Sub-types and inherited attributesDenormalising attributes and entitiesData Type and Name conversionsScalability of Process Automating & future-proofing the generation processEnterprise Data World, Chicago, April 5th 201126

27. Model Management ChallengesMultiple reference models require careful considerationE.g. Using OAG messaging standard as a reference model, extending it where requiredProvides a quick-start for defining schemasBe careful what you remove; perhaps remove nothingHow do you identify the parts that are actually in use?How do you know what extensions are needed?Have to map the standard to your own modelsEnterprise Data World, Chicago, April 5th 201127

28. Generating XML Models in PowerDesignerTwo optionsGenerate XML Model using default options, from selected tables, and tinker the XML afterwardsUse XML Builder to design and generate almost exactly what is required, and then tinker the XML model28Enterprise Data World, Chicago, April 5th 2011

29. Contact MeTelephone: +44 (0) 20 8123 8756 (forwarded to mobile)UK mobile: +44 (0) 794 293 0648Skype: gmcgeachieTwitter: metadatajunkieEmail: George.McGeachie @ MetadataMatters.comBlog: http://metadatajunkie.wordpress.com/Enterprise Data World, Chicago, April 5th 201129

30. Thanks for listening