1. Data Structure: Data Modeling or XML? Metatopia 2007 Washington, D.C. November 6, 2007 David C. Hay Essential Strategies, Inc. 13 Hilshire Grove Lane, Houston, TX 77055  (713) 464-8316  dch@essentialstrategies.com  www.essentialstrategies.com

2. /34 Copyright (c) 2007, Essential Strategies, Inc. 2 Agenda  Case Study: The Justice Department  Four ways to look at data  The Conceptual Entity/Relationship Model  The XML Version  An Examination  An Alternative Model  The Revised XML  The Federal Data Reference Model  Conclusions

3. /34 Copyright (c) 2007, Essential Strategies, Inc. 3 Agenda  Case Study: The Justice Department  Four ways to look at data  The Conceptual Entity/Relationship Model  The XML Version  An Examination  An Alternative Model  The Revised XML  The Federal Data Reference Model  Conclusions

4. /34 Copyright (c) 2007, Essential Strategies, Inc. 4 The heart of the problem... 1.U.S. Department of Justice. “Building Exchange Content Using the Global Justice XML Data Model: A User Guide for Practitioners and Developers”. June, 2005. p. v. (Available at: http://it.ojp.gov/topic.jsp?topic_id=201.) “Accurate and germane sharing of informa- tion across jurisdictions is a critical issue for justice and public safety. Although there has been significant progress in the field of infor- mation technology, the lack of standards for exchanging justice data has not only been a major obstacle to, but also the principal rea- son for, the high costs involved with justice information exchange.”1

5. /34 Copyright (c) 2007, Essential Strategies, Inc. 5 According to the Justice Department...  Sharing requires standards for exchanging data.  For this reason, they have developed the Global XML Data Model – in XML.  But sharing involves more than data exchange.  It means agreeing on semantics.  This means understanding the meaning of the data being exchanged... Not just the form and syntax. This calls for something more...

6. /34 Copyright (c) 2007, Essential Strategies, Inc. 6 Agenda  Case Study: The Justice Department  Four ways to look at data  The Conceptual Entity/Relationship Model  The XML Version  An examination  An alternative Model  The Revised XML  The Federal Data Reference Model  Conclusions

7. /34 Copyright (c) 2007, Essential Strategies, Inc. 7 Four ways to look at data External Schema 1 External Schema 2 External Schema 3 Conceptual Schema Internal Schema Internal Schema Physical Schema Physical Schema Logical Schema (Relnl.) Logical Schema (XML)

8. /34 Copyright (c) 2007, Essential Strategies, Inc. 8 Four ways to look at data External Schema 1 External Schema 2 External Schema 3   External Schema In particular viewer’s terms Overlapping May be inconsistent, at least in use of words. Difficult to reconcile different views

9. /34 Copyright (c) 2007, Essential Strategies, Inc. 9 Four ways to look at data Conceptual Schema Conceptual Schema Reconciles different external schema into one view. Reflects logical structure of data

10. /34 Copyright (c) 2007, Essential Strategies, Inc. 10 Four ways to look at data Internal Schema (Relnl.) Internal Schema (XML) Logical Schema (Relnl.) Logical Schema (XML)   Internal Schema Logical Schema – design in terms of a DBMS: tables and columns, object classes, etc. Physical Schema -- design of physical medium: cylinders, tablespaces, etc. Physical Schema Physical Schema

11. /34 Copyright (c) 2007, Essential Strategies, Inc. 11 Physical Schema Physical Schema In terms of the Architecture Framework... External Schema 1 External Schema 2 External Schema 3 Conceptual Schema Logical Schema (Relnl.) Business owners’ views Architect’s view Logical Schema (XML) Designers’ views Builders’ views

12. /34 Copyright (c) 2007, Essential Strategies, Inc. 12 Agenda  Case Study: The Justice Department  Four ways to look at data  The Conceptual Entity/Relationship Model  The XML Version  An examination  An alternative Model  The Revised XML  The Federal Data Reference Model  Conclusions

13. /34 Copyright (c) 2007, Essential Strategies, Inc. 13 The Conceptual Model (Schema)... External Schema 1 External Schema 2 External Schema 3 Conceptual Schema Logical Schema (Relnl.) Logical Schema (XML) Physical Schema Physical Schema

14. /34 Copyright (c) 2007, Essential Strategies, Inc. 14 The Conceptual Entity / Relationship Model...  Addresses the semantics of the organization.  Consists of assertions about the nature of the enterprise.  Is graphic, so it can be discussed with the business community.

15. /34 Copyright (c) 2007, Essential Strategies, Inc. 15 For example...

16. /34 Copyright (c) 2007, Essential Strategies, Inc. 16 Note the semantics... primarily about BOOKTOPIC addressed in Each BOOK must be primarily about one and only one TOPIC. Each TOPIC may be addressed in one or more BOOKS. For example...

17. /34 Copyright (c) 2007, Essential Strategies, Inc. 17 Ok, it’s true...  Many data modelers don’t care about semantics.  They only care about database design (the technical solution).  Just as XML advocates are promoting a technical solution. But semantics comes first!

18. /34 Copyright (c) 2007, Essential Strategies, Inc. 18 Agenda  Case Study: The Justice Department  Four ways to look at data  The Conceptual Entity/Relationship Model  The XML Version  An examination  An alternative Model  The Revised XML  The Federal Data Reference Model  Conclusions

19. /34 Copyright (c) 2007, Essential Strategies, Inc. 19 What is XML?

20. /34 Copyright (c) 2007, Essential Strategies, Inc. 20 XML is a kind of internal (Logical) schema... External Schema 1 External Schema 2 External Schema 3 Conceptual Schema Logical Schema (Relnl.) Logical Schema (XML) Physical Schema Physical Schema Designers’ view

21. /34 Copyright (c) 2007, Essential Strategies, Inc. 21 XML: The 1 Minute tutorial...  XML is a language for data communications.  It is based on tags defined by the creator. For example: BlackBerry  Notes: Each tag provides a label for that which follows it. Each tag must be accompanied by an end tag (</…) Tags are defined by a community within which communications are to take place. “All we have to do is to agree on the tags…”

22. /34 Copyright (c) 2007, Essential Strategies, Inc. 22 XML Schema: The 1 minute tutorial...  XML Schema is an XML document that defines the tags to configure other documents.  The “tags” are predefined in a WW3 namespace: Xs:schema xmins:xs=“http://www.w3.org/2001/XMLSchema”  Some of the tags include:  Key attributes of and : Name=“Chuck” Type=“xs:string” Use=“required” MinOccurs=“0” MaxOccurs=“unlimited”

23. /34 Copyright (c) 2007, Essential Strategies, Inc. 23 The XML Schema version of our model... <xs:complexType><xs:sequence> <xs:complexType><xs:sequence> <xs:complexType><xs:sequence> <xs:complexType> </xs:complexType></xs:element> <xs:complexType><xs:sequence> <xs:complexType>

24. /34 Copyright (c) 2007, Essential Strategies, Inc. 24 Of course one page isn’t enough... </xs:simpleContent></xs:complexType></xs:element></xs:sequence></xs:complexType></xs:element></xs:sequence></xs:complexType></xs:element></xs:sequence></xs:complexType></xs:element></xs:sequence> </xs:complexType></xs:element></xs:sequence></xs:complexType></xs:element></xs:schema>

25. /34 Copyright (c) 2007, Essential Strategies, Inc. 25 Agenda  Case Study: The Justice Department  Four ways to look at data  The Conceptual Entity/Relationship Model  The XML Version  An examination  An alternative Model  The Revised XML  The Federal Data Reference Model  Conclusions

26. /34 Copyright (c) 2007, Essential Strategies, Inc. 26 <xs:complexType><xs:sequence> <xs:complexType><xs:sequence> <xs:complexType><xs:sequence> <xs:complexType> </xs:complexType></xs:element> <xs:complexType><xs:sequence> <xs:complexType> Ok, Let’s look at that again... Entity classes Relationship cardinality (Default: must be 1) Attributes Attribute optionality

27. /34 Copyright (c) 2007, Essential Strategies, Inc. 27 </xs:complexType></xs:element></xs:sequence></xs:complexType></xs:element></xs:sequence></xs:complexType></xs:element></xs:sequence></xs:complexType></xs:element></xs:sequence> </xs:complexType></xs:element></xs:sequence></xs:complexType></xs:element></xs:schema> And, of course, the rest of it... You may not have noticed, but this is an attribute of WORKSHEET

28. /34 Copyright (c) 2007, Essential Strategies, Inc. 28 XML Spy does provide a graphic... Optional element Must be one or more elements

29. /34 Copyright (c) 2007, Essential Strategies, Inc. 29 But wait! There’s more to the model! In the data model, these were attributes of WORKBOOK

30. /34 Copyright (c) 2007, Essential Strategies, Inc. 30 More about Styles...

31. /34 Copyright (c) 2007, Essential Strategies, Inc. 31 Not to mention Worksheet Options, etc...

32. /34 Copyright (c) 2007, Essential Strategies, Inc. 32 Please forgive me for not showing you the six pages of resulting XML...

33. /34 Copyright (c) 2007, Essential Strategies, Inc. 33 What does this mean to the data model?

34. /34 Copyright (c) 2007, Essential Strategies, Inc. 34 Including some very strange things...

35. /34 Copyright (c) 2007, Essential Strategies, Inc. 35 The data model was inferred from the XML  Is it right? 2. My thanks to Peter Aiken for this example. 2

36. /34 Copyright (c) 2007, Essential Strategies, Inc. 36 Let’s look at the model again... Is not an EXCEL workbook a workbook? (Sub-type?) What is this relationship? Which column for this cell? Attributes of authors, company? What is this? … or this? Attributes of WORKBOOK? More authors?

37. /34 Copyright (c) 2007, Essential Strategies, Inc. 37 XML limitations...  XML is fundamentally hierarchical... Cannot have multiple parents  Can describe a transaction, but... Assumes validity of data  Can impose cardinality rules  Can impose syntactic rules  No rules based on the meaning of the data.  Cannot describe semantics of relationships  Cannot be presented to normal human beings.

38. /34 Copyright (c) 2007, Essential Strategies, Inc. 38 In Fairness...  While E/R modeling can more effectively portray the meaning of the data, it too is limited in its ability to portray business rules.  New tools (such as XML Spy) are making it possible to deal with XML graphically.

39. /34 Copyright (c) 2007, Essential Strategies, Inc. 39 Agenda  Case Study: The Justice Department  Four ways to look at data  The Conceptual Entity/Relationship Model  The XML Version  An examination  An alternative Model  The Revised XML  The Federal Data Reference Model  Conclusions

40. /34 Copyright (c) 2007, Essential Strategies, Inc. 40 Add network... With Data Modeling, we have an alternative......and a sub-type?...many-to-many......reference entity classes…...collapsed entities... Border position Number format Font Color Vertical alignment etc.

41. /34 Copyright (c) 2007, Essential Strategies, Inc. 41 Agenda  Case Study: The Justice Department  Four ways to look at data  The Conceptual Entity/Relationship Model  The XML Version  An examination  An alternative Model  The Revised XML  The Federal Data Reference Model  Conclusions

42. /34 Copyright (c) 2007, Essential Strategies, Inc. 42 To convert a data model to XML...  Identify a hierarchy. NOTE: Several may be available.  Establish one direction for many-to-many relationships.  Move intersect attributes to new “many” side.  Inherit attributes from parents to children entity classes.

43. /34 Copyright (c) 2007, Essential Strategies, Inc. 43 Here’s one version...

44. /34 Copyright (c) 2007, Essential Strategies, Inc. 44 And create a constrained model...

45. /34 Copyright (c) 2007, Essential Strategies, Inc. 45 The Resulting XML (the graphic version, at least)...

46. /34 Copyright (c) 2007, Essential Strategies, Inc. 46 More about the Worksheet...

47. /34 Copyright (c) 2007, Essential Strategies, Inc. 47 Here’s a second version... Only primary author is included

48. /34 Copyright (c) 2007, Essential Strategies, Inc. 48 And create a constrained model...

49. /34 Copyright (c) 2007, Essential Strategies, Inc. 49 The Resulting XML...

50. /34 Copyright (c) 2007, Essential Strategies, Inc. 50 With Worksheet Details...

51. /34 Copyright (c) 2007, Essential Strategies, Inc. 51 Agenda  Case Study: The Justice Department  Four ways to look at data  The Conceptual Entity/Relationship Model  The XML Version  An examination  An alternative Model  The Revised XML  The Federal Data Reference Model  Conclusions

52. /34 Copyright (c) 2007, Essential Strategies, Inc. 52 Federal Enterprise Architecture... 3. CIO Council, Office of Management and Budget. 3

53. /34 Copyright (c) 2007, Essential Strategies, Inc. 53 Data Sharing Data Context Query Points and Exchange Packages (XML) Taxonomies (Categories) (Function/data Usage) Data Description Data Elements (E/R Model) Specifically, the Data Reference Model...

54. /34 Copyright (c) 2007, Essential Strategies, Inc. 54 Data Sharing Data Context Query Points and Exchange Packages (XML) Taxonomies (Categories) (Function/data Usage) Data Description Data Elements (E/R Model) But you must understand when you are not doing this but this.

55. /34 Copyright (c) 2007, Essential Strategies, Inc. 55 Agenda  Case Study: The Justice Department  Four ways to look at data  The Conceptual Entity/Relationship Model  The XML Version  An examination  An alternative Model  The Revised XML  The Federal Data Reference Model  Conclusions

56. /34 Copyright (c) 2007, Essential Strategies, Inc. 56 Conclusions...  XML is very good for data communications. English syntax is convenient. XML Schema is very powerful for describing the structure of transactions It is widely accepted. Graphic tools make it more manageable.  Semantic data modeling is better for analyzing data structure. Graphic nature makes it suitable for discussing semantic issues. Two dimensional format makes it possible to describe networks.

57. /34 Copyright (c) 2007, Essential Strategies, Inc. 57 More significantly...  But XML is fundamentally a technological design. ...while conceptual data modeling is fundamen- tally a way to describe the business problem. It’s important to understand the difference.

58. /34 Copyright (c) 2007, Essential Strategies, Inc. 58 It’s better to start with the Data Model (More Semantics) And then derive the XML script from that (Less Semantics)

59. /34 Copyright (c) 2007, Essential Strategies, Inc. 59 Questions?