1. Copyright (c) 2006 Essential Strategies, Inc. 1 1 Eyesight check: Can you read this? If not, you may want to move closer to the screen...

2. Data Modeling and OWL David C. Hay Metatopia Washington, DC November 6, 2007 Essential Strategies, Inc. 13 Hilshire Grove Lane, Houston, TX 77055  (713) 464-8316  dch@essentialstrategies.com  www.essentialstrategies.com

3. Copyright (c) 2006 Essential Strategies, Inc. 3 How we use language is important...

4. Copyright (c) 2006 Essential Strategies, Inc. 4 Challenges We are drowning in information From databases in our companies From the World-wide Web in our education This calls for more effective systems: Provide more (the right?) information In spite of Ambiguous human descriptions Software that demands specificity

5. Copyright (c) 2006 Essential Strategies, Inc. 5 Agendums Definitions About Data Models About Ontology Languages The Foundation: The Semantic Web RDF: Resource Description Framework RDF Schema OWL: Web Ontology Language Converting a Sample Data Model What’s different

6. Copyright (c) 2006 Essential Strategies, Inc. 6 Agendums Definitions About Data Models About Ontology Languages The Foundation: The Semantic Web RDF: Resource Description Framework RDF Schema OWL: Web Ontology Language Converting a Sample Data Model What’s different

7. Copyright (c) 2006 Essential Strategies, Inc. 7 Theory of meaning; study of the signification of signs or symbols, as opposed to their formal relations (syntactics). Different parts of an organization use language in different ways. Different systems manage data With the same name that mean different things With different names that mean the same things. For systems (or departments, for that matter) to communicate, semantics must be addressed. The company’s ontology must be created. What is semantics? 1 1.G. Kemmerling. Philosophical Dictionary. http://www.philosophypages.com/dy/s4.htm#sems. 2002

8. Copyright (c) 2006 Essential Strategies, Inc. 8  From philosophy: “The Branch of metaphysics concerned with identifying, in the most general terms, the kinds of things that actually exist.”  A catalog of the types of things that are assumed to exist...  …in a domain of interest  …with rules governing how those terms can be combined to make valid statements  …and “sanctioned inferences” that can be made. What is an ontology? 2 2.G. Kemmerling. Philosophical Dictionary. http://www.philosophypages.com/dy/o.htm#onty. 2002 3.Knowledge Based Systems, Inc., Information Integration For Concurrent Engineering. Prepared for Armstrong Laboratory AL/HRGA. 1994 3

9. Copyright (c) 2006 Essential Strategies, Inc. 9 What is an ontology? A data model is an example of an ontology. Other approaches to building ontologies are being developed.

10. Copyright (c) 2006 Essential Strategies, Inc. 10 In summary... Ontology tells us what exists. Semantics tells us how to describe it.

11. Copyright (c) 2006 Essential Strategies, Inc. 11 Agendums Definitions About Data Models About Ontology Languages The Foundation: The Semantic Web RDF: Resource Description Framework RDF Schema OWL: Web Ontology Language Converting a Sample Data Model What’s different

12. Copyright (c) 2006 Essential Strategies, Inc. 12 Modeling Techniques: What is a data model? Commonly equivalent to database design. Not here. Model of an organization’s semantics—The structure of its information. Describes: Things of significance to the business. What characteristics describe those things. How the things are related to each other. We’re talking about the conceptual data model, here.

13. Copyright (c) 2006 Essential Strategies, Inc. 13 Objectives of Data Model Capture the semantics of the organization. Communicate these to the business without requiring technical skills. Provide an architecture to use as the basis for database and system design. Now: Provide the basis for designing Service Oriented Architectures.

14. Copyright (c) 2006 Essential Strategies, Inc. 14 A Sample Data Model... Definitions of things of significance... Definitions of relationships among those things... Definitions of information about those things...

15. Copyright (c) 2006 Essential Strategies, Inc. 15 The Semantics of a Data Model CITYSTATE located in the location of Each [or] [or] one or more must be <relationship name> primarily about <first entity> BOOK <second entity> TOPIC one and only one Each CITY must be located in one and only one STATE. Each STATE may be the location of one or more CITIES. may be

16. Copyright (c) 2006 Essential Strategies, Inc. 16 ( Yes, most people don’t name relationships like that in data models) The only approach that reveals the semantics of the relationship. Specific approach to data modeling naming, developed in the 1980’s. Promoted by Oracle Corporation in its CASE tools and training. Used in the European System Specification and Design Methodology (SSADM). The use of this approach is finally being vindicated!!

17. Copyright (c) 2006 Essential Strategies, Inc. 17 Data Models and Business Rules... Data models describe structure. What can be done? They are designed to represent what is permanent about the organization. Business rules are about constraints on that structure. What cannot be or must be done? Except for cardinality, business rules cannot be represented on a data model. Which is good, since business rules can change.

18. Copyright (c) 2006 Essential Strategies, Inc. 18 Data modeling, database design, and business rule specification are very different Note... Today we are going to discover a completely different mindset. They are, however, part of a particular mindset.

19. Copyright (c) 2006 Essential Strategies, Inc. 19 Something new is coming...

20. Copyright (c) 2006 Essential Strategies, Inc. 20 Something new is coming... If you come to this presentation as a data modeler... Hold onto your seats... There really is a new world out there... Well, maybe not that new......but you definitely have an opportunity to broaden your horizons today.

21. Copyright (c) 2006 Essential Strategies, Inc. 21 Agendums Definitions About Data Models About Ontology Languages The Foundation: The Semantic Web RDF: Resource Description Framework RDF Schema OWL: Web Ontology Language Converting a Sample Data Model What’s different

22. Copyright (c) 2006 Essential Strategies, Inc. 22 From philosophy: The study of that which exists. Now: Collections of facts about an organization In a domain With automatable rules for inference Ontologies Again, about ontologies...

23. Copyright (c) 2006 Essential Strategies, Inc. 23 Ontology languages Data models (and the databases based on them)... …are a kind of ontology …are about defining categories of data …establish (directly or indirectly) rules for collecting data in those categories. …and are defined by humans New ontology languages... …begin with instances of actual data …classify them …so computers can make inferences from them.

24. Copyright (c) 2006 Essential Strategies, Inc. 24 Data models and relational databases are based on the closed world assumption: An ontology language is based on the open world assumption: The assumptions behind them are completely different... Only that which is asserted to be true is true. All assertions are assumed to be true until proven otherwise.

25. Copyright (c) 2006 Essential Strategies, Inc. 25 This means... In a relational database, You can only enter data that you know to be true. You are “encouraged” to enter complete information. There are no other data. Data model entity classes are templates. In an ontologogical database, You can enter what you know to be true. You can enter incomplete information. You (and the computer) can infer other things. Ontology classes are sets of things

26. Copyright (c) 2006 Essential Strategies, Inc. 26 Agendums Definitions About Data Models About Ontology Languages The Foundation: The Semantic Web RDF: Resource Description Framework RDF Schema OWL: Web Ontology Language Converting a Sample Data Model What’s different

27. Copyright (c) 2006 Essential Strategies, Inc. 27 What is the Semantic Web? A World-wide web of interconnected machine-understandable information A single, virtual gigantic database of machine- understandable information Not just linking documents, but having software recognize the contents of those documents. Previously, search by names, keys—or SQL. Now search by semantic constructs.

28. Copyright (c) 2006 Essential Strategies, Inc. 28 Semantic Web Layered Architecture Applications Implementation Layer Ontology Languages (OWL) Logical Layer IndividualsRDF Schema Ontological Primitive Layer RDF and RDF/XML Basic Relational Language Layer XML and XMLS Datatypes How data are communicated URI’s and Namespaces The names of things

29. Copyright (c) 2006 Essential Strategies, Inc. 29 URI’s and Namespaces Uniform Resource Identifier – Portrays the identity of anything (abstract or physical). Structure: Scheme name: Scheme-specific name Not controlled: You can name a resource anything you want. E.g., hay:dave Applications Ontology Languages IndividualsRDF Schema RDF and RDF/XML XML and XMLS Datatypes URI’s and Namespaces

30. Copyright (c) 2006 Essential Strategies, Inc. 30 URI’s and Namespaces Applications Ontology Languages IndividualsRDF Schema RDF and RDF/XML XML and XMLS Datatypes URI’s and Namespaces Uniform Resource Locator – A Uniform Resource Identifier that identifies a primary network access mechanism (acts as a locator) Used to locate resources on the World-wide Web Controlled: Stem assigned by the Internet Corporation For Assigned Names and Numbers (ICANN). E.g., http://www.essentialstrategies.com

31. Copyright (c) 2006 Essential Strategies, Inc. 31 Namespaces XML Namespace – a URI that describes an ontology from which terms are taken. A prefix is usually assigned to each namespace to simplify refering to terms. For example, the OWL namespace is: xmlns:owl="http://www.w3.org/2002/07/owl” In the OWL namespace, the term “class” would be shown thus: xmlns:owl= "http://www.w3.org/2002/07/owl#class" Once the namespace is declared, this can be abbreviated: Owl:Class Applications Ontology Languages IndividualsRDF Schema RDF and RDF/XML XML and XMLS Datatypes URI’s and Namespaces

32. Copyright (c) 2006 Essential Strategies, Inc. 32 XML and XMLS Datatypes (1 Minute XML tutorial)... XML is a language for data communications. It is used to express RDF and OWL constructs. 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 (</…) Applications Ontology Languages IndividualsRDF Schema RDF and RDF/XML XML and XMLS Datatypes URI’s and Namespaces

33. Copyright (c) 2006 Essential Strategies, Inc. 33 XML and XMLS Datatypes XML Schema is an XML document that configures other documents. RDF and OWL are defined in XML Schema. Applications Ontology Languages IndividualsRDF Schema RDF and RDF/XML XML and XMLS Datatypes URI’s and Namespaces 1/4

34. Copyright (c) 2006 Essential Strategies, Inc. 34 <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:contact="http://www.w3.org/2000/10/swap/pim/contact#"> Dave Hay Mr. URIs show up in XML as follows: RDF namespace Contact namespace Contact terminology (term is concatenated to Contact namespace for full URI) http://www.w3.org/2000/10/swap/pim/contact# person http://www.w3.org/2000/10/swap/pim/contact# fullname http://www.w3.org/2000/10/swap/pim/contact# mailbox http://www.w3.org/2000/10/swap/pim/contact# personalTitle Applications Ontology Languages IndividualsRDF Schema RDF and RDF/XML XML and XMLS Datatypes URI’s and Namespaces The tags are equivalent to this:

35. Copyright (c) 2006 Essential Strategies, Inc. 35 And note: Applications Ontology Languages IndividualsRDF Schema RDF and RDF/XML XML and XMLS Datatypes URI’s and Namespaces This structure Dave Hay Mr. Asserts that person is described by fullName (Dave Hay), mailbox (mailto:em@w3.org), and personalTitle (Mr).

36. Copyright (c) 2006 Essential Strategies, Inc. 36 Agendums Definitions About Data Models About Ontology Languages The Foundation: The Semantic Web RDF: Resource Description Framework RDF Schema OWL: Web Ontology Language Converting a Sample Data Model What’s different Applications Ontology Languages IndividualsRDF Schema RDF and RDF/XML XML and XMLS Datatypes URI’s and Namespaces

37. Copyright (c) 2006 Essential Strategies, Inc. 37 RDF and RDF/XML The Resource Description Framework is the basic language layer of data representation. Used as metadata to describe, for example, documents and images. Used to make simple statements of the form Rendered in XML. RDF consists of a set of pre-defined tags in XML. Applications Ontology Languages IndividualsRDF Schema RDF and RDF/XML XML and XMLS Datatypes URI’s and Namespaces

38. Copyright (c) 2006 Essential Strategies, Inc. 38 Example of RDF... Kleenex brand tissues are sold by Kimberly Clark Corporation Applications Ontology Languages IndividualsRDF Schema RDF and RDF/XML XML and XMLS Datatypes URI’s and Namespaces NOTE: There is no distinction between classes and instances.

39. Copyright (c) 2006 Essential Strategies, Inc. 39 RDF and “Data modeling” Entity class = Relationship = + Attribute = an attribute of Applications Ontology Languages IndividualsRDF Schema RDF and RDF/XML XML and XMLS Datatypes URI’s and Namespaces NOTE: There is no distinction between classes and instances.

40. Copyright (c) 2006 Essential Strategies, Inc. 40 RDF Tags Tags for statements Plus tags for collecting instances Applications Ontology Languages IndividualsRDF Schema RDF and RDF/XML XML and XMLS Datatypes URI’s and Namespaces

41. Copyright (c) 2006 Essential Strategies, Inc. 41 Agendums Definitions About Data Models About Ontology Languages The Foundation: The Semantic Web RDF: Resource Description Framework RDF Schema OWL: Web Ontology Language Converting a Sample Data Model What’s different

42. Copyright (c) 2006 Essential Strategies, Inc. 42 RDF Schema... Extends RDF Adds resource, class, sub-class, range, domain, etc. RDF is actually specified using RDFS tags. Applications Ontology Languages IndividualsRDF Schema RDF and RDF/XML XML and XMLS Datatypes URI’s and Namespaces

43. Copyright (c) 2006 Essential Strategies, Inc. 43 RDFS and Data Modeling Applications Ontology Languages IndividualsRDF Schema RDF and RDF/XML XML and XMLS Datatypes URI’s and Namespaces Entity class = Attribute = Relationship = Instance = For example: Product Party

44. Copyright (c) 2006 Essential Strategies, Inc. 44 Note: In RDF all relationships are optional many-to-many. There are no cardinality constraints. Applications Ontology Languages IndividualsRDF Schema RDF and RDF/XML XML and XMLS Datatypes URI’s and Namespaces

45. Copyright (c) 2006 Essential Strategies, Inc. 45 RDF Schema tags... About Resources Documentation Extent of properties Applications Ontology Languages IndividualsRDF Schema RDF and RDF/XML XML and XMLS Datatypes URI’s and Namespaces Definitions Containers <rdfs: containerMembershipProperty> Miscellaneous

46. Copyright (c) 2006 Essential Strategies, Inc. 46 Agendums Definitions About Data Models About Ontology Languages The Foundation: The Semantic Web RDF: Resource Description Framework RDF Schema OWL: Web Ontology Language Converting a Sample Data Model What’s different

47. Copyright (c) 2006 Essential Strategies, Inc. 47 Ontology Languages... RDF constructs are not rich enough: Few descriptors support inferencing Not expressive enough to support the WWW. Web Ontology Language (OWL) adds tags. Three species: OWL Full OWL Lite OWL DL NOTE: IDEF5, from the federal government also addressed this. Applications Ontology Languages IndividualsRDF Schema RDF and RDF/XML XML and XMLS Datatypes URI’s and Namespaces * * In Winnie the Pooh, Owl imagines that his name is spelled “WOL”, until his friends correct him. Here, the W3C decided to start with the correct spelling.

48. Copyright (c) 2006 Essential Strategies, Inc. 48 Open world assertion: All may be true unless asserted otherwise Two airports with different names could be the same airport. Instance AA243 may be a flight or an airport. Must explicitly declare instances and classes to be disjoint. (If “AA243” is a flight, it cannot be an airport.) Begin with instances; then classify by properties Class of red things Multiple inheritance Attributes and attribute values can be used to define multiple classes. About OWL... Applications Ontology Languages IndividualsRDF Schema RDF and RDF/XML XML and XMLS Datatypes URI’s and Namespaces

49. Copyright (c) 2006 Essential Strategies, Inc. 49 The OWL parts of a data model Entity class = Attribute = Relationship = NOTE:  Both attributes and relationships are properties  They are defined first, then attached to one or more classes.

50. Copyright (c) 2006 Essential Strategies, Inc. 50 For example...  Define class:  Add attribute:  Add Relationship: Actually, it’s more complicated than this, but this will get you started...

51. Copyright (c) 2006 Essential Strategies, Inc. 51 Identifying Instances... Identify individual instances:

52. Copyright (c) 2006 Essential Strategies, Inc. 52 OWL Tags... Classes Ontology Nothing Thing (complement of Nothing) Class AllDifferent Restriction DeprecatedClass DeprecatedProperty DataRange Rdf: Property ObjectProperty TransitiveProperty SymmetricProperty InverseFunctionalProperty DatatypeProperty OntologyProperty FunctionalProperty AnnotationProperty

53. Copyright (c) 2006 Essential Strategies, Inc. 53 OWL Tags, continued Properties (Domain, Range) equivalentClass (Class 1, Class 2) equivalentProperty (Property 1, Property 2) disjointWith (Class 1, Class 2) sameAs (Thing 1, Thing 2) differentFrom (Thing 1, Thing 2) distinctMembers (AllDifferent, &rdf;List) unionOf (Class, &rdf;List) intersectionOf (Class, &rdf;List) complementOf (Class 1, Class 2) oneOf (&rdfs;Class, &rdf;List) onProperty (Restriction, &rdf;Property) allValuesFrom (Restriction, &rdfs;Class) hasValue (Restriction) someValuesFrom (Restriction, &rdfs;Class) minCardinality (Restriction, &xsd;nonNegativeInteger) maxCardinality (Restriction, &xsd;nonNegatieInteger Cardinality (Restriction, &xsd;nonNegativeInteger

54. Copyright (c) 2006 Essential Strategies, Inc. 54 OWL Tags, continued Properties (Domain, Range) inverseOf (ObjectProperty 1, ObjectProperty 2) imports (Ontology 1, Ontology 2) versionInfo priorVersion (Ontology 1, Ontology 2) backwardCompatibleWith (Ontology 1, Ontology 2) incompatibleWith (Ontology 1, Ontology 2)

55. Copyright (c) 2006 Essential Strategies, Inc. 55 Agendums Definitions About Data Models About Ontology Languages The Foundation: The Semantic Web RDF: Resource Description Framework RDF Schema OWL: Web Ontology Language Converting a Sample Data Model What’s different 1/2

56. Copyright (c) 2006 Essential Strategies, Inc. 56 Converting a data model to OWL Both are about the structure of data It is (mostly) mechanical to translate one to another. The implications, however, are profound.

57. Copyright (c) 2006 Essential Strategies, Inc. 57 A Sample Data model (Begin with a taxonomy)...

58. Copyright (c) 2006 Essential Strategies, Inc. 58 Defining Classes in Protégé...

59. Copyright (c) 2006 Essential Strategies, Inc. 59 The Generated XML – Introduction (Namespaces) <rdf:RDF xmlns:Geo="http://www.domain2.com#" xmlns:protege= "http://protege.stanford.edu/plugins/owl/protege#" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:xsd="http://www.w3.org/2001/XMLSchema#" xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#" xmlns:owl="http://www.w3.org/2002/07/owl#" xmlns:daml="http://www.daml.org/2001/03/daml+oil#" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns="http://www.essentialstrategies.com/OWL/Geographyl#" xml:base="http://www.essentialstrategies.com/OWL/Geographyl">

60. Copyright (c) 2006 Essential Strategies, Inc. 60 The Generated XML – Geographic Location... NOTE: Every class is at least a sub-type of “Thing”.

61. Copyright (c) 2006 Essential Strategies, Inc. 61 The Generated XML – Geopolitical Area... Note two (equivalent) approaches...

62. Copyright (c) 2006 Essential Strategies, Inc. 62 <owl:Class rdf:ID=" GEOGRAPHIC_TELEPHONE_AREA “ The Generated XML – Remaining Geographic Locations...

63. Copyright (c) 2006 Essential Strategies, Inc. 63 First Consraint – “disjoint”

64. Copyright (c) 2006 Essential Strategies, Inc. 64 The OWL version of disjointedness... <rdfs:comment rdf:datatype="http://www.w3.org/2001 /XMLSchema#string"> A GEOGRAPHICAL_AREA whose boundaries are set by law or treaty.

65. Copyright (c) 2006 Essential Strategies, Inc. 65 Adding Attributes to the Data Model...

66. Copyright (c) 2006 Essential Strategies, Inc. 66 The OWL version... “Attribute” becomes “datatype property” Datatype properties are defined first, and then assigned to a class. Domain means the class that the datatype property is an attribute of. Range specifies a URL to describe the format. Note: Once a datatype property is assigned to a particular class, the name cannot be re-used with any other. (More about this constraint, later.)

67. Copyright (c) 2006 Essential Strategies, Inc. 67 The Protégé and Properties...

68. Copyright (c) 2006 Essential Strategies, Inc. 68 Protégé Assigns Properties to Classes...

69. Copyright (c) 2006 Essential Strategies, Inc. 69 XML/OWL statements about properties...

70. Copyright (c) 2006 Essential Strategies, Inc. 70 <rdfs:range rdf:datatype=http://www.w3.org/2001/XMLSchema#string/>http://www.w3.org/2001/XMLSchema#string <rdfs:range rdf:datatype="http://www.w3.org/2001/XMLSchema#string"> XML/OWL statements about properties...

71. Copyright (c) 2006 Essential Strategies, Inc. 71 Adding relationships to the Data Model...

72. Copyright (c) 2006 Essential Strategies, Inc. 72 Two versions of Relationships... Version 1 Object property, e.g., “located in state” Domain: first class Range: second class May only be used to define relationships from the first class Version 2 Object property, e.g., “located in” Makes first class a subtype of class that defines a restriction The restriction is the specified property …in terms of some or all values of second class. May be used with any first class

73. Copyright (c) 2006 Essential Strategies, Inc. 73 About relationships in OWL (Version 1) Define classes Then define object property in terms of: Domain – The class being related Range – The class being related to Must have unique name in namespace E.g. “locatedInSTATE” and “locatedInCOUNTRY” must be different. Can use union of classes for Domain E.g., instances of COUNTY and CITY may be located in STATE.

74. Copyright (c) 2006 Essential Strategies, Inc. 74 The Cerebra View (Version 1)... Note: Union

75. Copyright (c) 2006 Essential Strategies, Inc. 75 Version 1 of an object property in OWL... [Define City, State, and County…]

76. Copyright (c) 2006 Essential Strategies, Inc. 76 Version 1 of an object property in OWL... “FunctionalProperty” means that only one value of the range is permitted (and one is required) for each value of the domain.

77. Copyright (c) 2006 Essential Strategies, Inc. 77 Relationship as ObjectProperty (Protégé)...

78. Copyright (c) 2006 Essential Strategies, Inc. 78 Version 1 of an object property in OWL...  Since the first object property (“located_in_state”) was tied to the range (“STATE”), it can only be used in cases where that is the range.  “Located_in_country” must have different name.  Can make it “functional” meaning “…must be no more than one…”  Or can explicitly add cardinality.

79. Copyright (c) 2006 Essential Strategies, Inc. 79 About relationships in OWL, version 2 For each “from” class Define restriction as super-class of the “from” class onProperty = “located in” someValuesFrom = Can re-use “located in” 3/4

80. Copyright (c) 2006 Essential Strategies, Inc. 80 The Cerebra View (Version 2)...

81. Copyright (c) 2006 Essential Strategies, Inc. 81 1 Version 2 of an object property in OWL... [continued on next page] First define an object property... Then assign it to a STATE to put it in a COUNTRY...

82. Copyright (c) 2006 Essential Strategies, Inc. 82 Version 2 of an object property in OWL... 1 [continued from last page] [continued on next page]

83. Copyright (c) 2006 Essential Strategies, Inc. 83 Version 2 of an object property in OWL... [continued from last page] 1

84. Copyright (c) 2006 Essential Strategies, Inc. 84 Version 2 of an object property in OWL...  Restriction can be reused to be “located in Country”.  Cannot be “functional”, but can be “transitive”.  Can use cardinality restriction.

85. Copyright (c) 2006 Essential Strategies, Inc. 85 Note: More About Datatype Properties... The approach described above: <rdfs:range rdf:datatype= "http://www.w3.org/2001/XMLSchema#string"> Has the same limitations as the approach to relationships Cannot duplicate the name.

86. Copyright (c) 2006 Essential Strategies, Inc. 86 Version 2 is also available for Datatype Properties... 1 No t e

87. Copyright (c) 2006 Essential Strategies, Inc. 87 1 Version 2 is also available for Datatype Properties... No t e

88. Copyright (c) 2006 Essential Strategies, Inc. 88 Agendums Definitions About Data Models About Ontology Languages The Foundation: The Semantic Web RDF: Resource Description Framework RDF Schema OWL: Web Ontology Language Converting a Sample Data Model What’s different

89. Copyright (c) 2006 Essential Strategies, Inc. 89 What’s Different... Audience... Purpose... Premises... Constructing Classes... Approach to Constraints...

90. Copyright (c) 2006 Essential Strategies, Inc. 90 What’s different: Audience... Data Modeling... Human beings Ontology Languages... Computers We’re still waiting for the utility that allows us to automate the conversion of a conceptual (semantic) data model to an OWL script.

91. Copyright (c) 2006 Essential Strategies, Inc. 91 What’s Different: Purpose Data Modeling: Control data when entered Only accept “correct” data Ontology Languages Use existing data as extensively as possible Analyze existing data to see what’s true

92. Copyright (c) 2006 Essential Strategies, Inc. 92 What’s Different: Premise Data Modeling: Closed world Only what is asserted is the case Ontology Languages Open world Anything is possible if it is consistent with assertions

93. Copyright (c) 2006 Essential Strategies, Inc. 93 What’s Different: Constructing Classes Data Modeling Begin with class definitions of fundamental categories Define attributes Identify instances Ontology Languages Begin with instances Identify attributes Define classes based on attributes (Accept multiple inheritance)

94. Copyright (c) 2006 Essential Strategies, Inc. 94 What’s Different: Approach to Constraints Data Modeling (plus Business Rules) Determine what data are acceptable Reject data that do not conform Ontology Languages Assert what is true Infer what else may be true

95. Copyright (c) 2006 Essential Strategies, Inc. 95 For example, in data modeling... Each CITY must be located in one and only one STATE. If “Portland” is entered as a CITY without a STATE then it is not accepted. If “Portland” is entered as a CITY and linked to STATE “Maine”, then a record with the CITY “Portland” linked to STATE “Oregon” is not accepted.

96. Copyright (c) 2006 Essential Strategies, Inc. 96 For example, in ontology languages Each CITY must be located in one and only one STATE. 1. “Portland” may be entered without a STATE 2. If “Portland” is entered “located in” “Maine” And “Portland” is identified as a CITY Then “Maine” must be a STATE (inference) 3. If “Portland is then entered “located in” “Oregon” And “Portland” is identified as a CITY Then “Oregon” must be a STATE (Inference) And either: “Oregon” and “Maine” must be the same state (Inference) Or “Portland” in “Oregon” and “Portland” in “Maine” must be different cities. (Inference)

97. Copyright (c) 2006 Essential Strategies, Inc. 97 Note that OWL is much more subtle in being able to distinguish between the name of something and what is being referred to by that name.

98. Copyright (c) 2006 Essential Strategies, Inc. 98 Synopsis Both data modeling and ontology languages represent the structure of business data (ontologies) Data modeling represents data being collected, and filters according to rules Ontology languages represent data being used, with ability to have computer make inferences.

99. Copyright (c) 2006 Essential Strategies, Inc. 99 Ok, one commercial... An article based on this paper was published as a Cutter Consortium Executive Report. You can download it at http://www.cutter.com/offers/semantics.html. http://www.cutter.com/offers/semantics.html Also: And http://www.essetialstrategies.com/publications Data Model Patterns: Conventions of Thought. Dorset House, 1995. Requirements Analysis: From Business Views to Architecture. Prentice Hall, 2003. Data Model Patterns: A Metadata Map. Morgan Kaufmann, 2006.