Interoperability Standards at Levels of Syntax and Semantics

1. World Meteorological Organizations (WMO)Observing and Information Systems DepartmentWMO Information System (WIS) Interoperability Standards at Levels of Syntax and Semantics Presentedby Eliot Christian <echristian@wmo.int>at the First Meeting of WMO / CBS / ISS / ET-ADRS (Expert Team On Assessment Of Data Representation Systems) in Silver Spring, MD, USA on 23 - 25 April 2008

2. Syntax and Semantics • Semantics deals with the meaning of a symbol in some language • Syntax deals with handling of symbols independent of their meaning, e.g., • ASN.1 (Abstract Syntax Notation) • XML (eXtensible Markup Language) Interoperability Standards at Levels of Syntax and Semantics

3. Standards-based Interoperability at the Level of Syntax • Structure Types, e.g., • sub-element is part of element • record is part of file • table has three dimensions • Data Types, e.g., • integers or decimal numbers ... • dates, times, coordinates ... • text, images, sound ... • Indicating structure in an instance, e.g., • start-position, length • mark-up with start-end tagging Interoperability Standards at Levels of Syntax and Semantics

4. ASN.1 Snippet PDU ::= CHOICE{ searchRequest [22] IMPLICIT SearchRequest, searchResponse [23] IMPLICIT SearchResponse, SearchRequest ::= SEQUENCE{ resultSetName [17] IMPLICIT InternationalString, databaseNames [18] IMPLICIT SEQUENCE OF DatabaseName, query [21] Query SearchResponse ::= SEQUENCE{ resultCount [23] IMPLICIT INTEGER, numberOfRecordsReturned [24] IMPLICIT INTEGER, nextResultSetPosition [25] IMPLICIT INTEGER, searchStatus [22] IMPLICIT BOOLEAN, resultSetStatus [26] IMPLICIT INTEGER, records Records OPTIONAL, Interoperability Standards at Levels of Syntax and Semantics

5. Comparing ASN.1 and XML Syntactic Mechanisms Interoperability Standards at Levels of Syntax and Semantics

6. ASN.1 and Encoding Rules In ASN.1, concrete syntax ("on-the-wire encoding") is handled separately from the abstract syntax:ASN.1 "Encoding Rules" are applied to make actual messages in compliance with an ASN.1 specification • Basic Encoding Rules (BER): represent each byte present, as defined in the specification • Packed Encoding Rules (PER): group repeated bytes • Distinguished Encoding Rules (DER): represent only bytes that change, on a message to message basis • XML Encoding Rules (XER): translate between ASN.1 elements and their XML equivalents Interoperability Standards at Levels of Syntax and Semantics

7. ASN.1 and XML Interoperability using XML Encoding Rules • An XML Encoding Rules (XER) tool can generate, automatically and losslessly: • an XML schema from an ASN.1 specification OR • an ASN.1 specification from an XML schema • In addition, XER can be applied at the instance level rather than the schema level, i.e., XER converters inserted at both ends of a communications link will enhance transmission efficiency "on-the-fly" Interoperability Standards at Levels of Syntax and Semantics

8. Example: Common Alerting ProtocolUses XER to Bridge ASN.1 and XML • Common Alerting Protocol (CAP) standardizes all-hazards, all-media public warning messages • Message formats in the CAP standard were originally defined using XML Schema • XER was used to create an ASN.1 specification for CAP messages, required for ITU adoption • International Telecommunication Union (ITU) adopted CAP as ITU Recommendation X.1303 Interoperability Standards at Levels of Syntax and Semantics

9. Standards-based Interoperability at the Level of Semantics Interoperability Standards at Levels of Syntax and Semantics

10. Standards-based Interoperability at the Level of Semantics • Semantic interoperability is often constrained in practice by a lack of available data definitions • It is risky to integrate or transform any data or information element without its explicit definition • ISO/IEC 11179, Metadata Registries, provides useful guidance for documenting the meanings of data or information elements • The objective is to have good definitions for data and information elements, not to fully automate inferencing (sometimes called "Semantic Web") Interoperability Standards at Levels of Syntax and Semantics

11. Example: CAP Data Dictionary Interoperability Standards at Levels of Syntax and Semantics

12. Actions Proposed • Syntactic interoperability should be achieved using automated transformations, based on standardized syntax description languages • Syntactic interoperability cannot assure that information is meaningful--precise definitions of data and information elements are necessary • ISO/IEC 11179, Metadata Registries, provides useful guidance for defining elements, within and among data dictionaries • A policy promoting use of ISO/IEC 11179 would complement broader use of ISO 191xx series of standards, especially ISO 19115 Interoperability Standards at Levels of Syntax and Semantics

13. Questions? References: GEOSS (Global Earth Observation System of Systems) 10 Year Implementation Plan and Reference Document http://earthobservations.org/ ISO/IEC 11179 Metadata Registries http://standards.iso.org/ittf/PubliclyAvailableStandards/ c035343_ISO_IEC_11179-1_2004(E).zip Interoperability Standards at Levels of Syntax and Semantics

14. Using Registriesto Manage Data / Metadata Syntax and Semantics Interoperability Standards at Levels of Syntax and Semantics

15. Registries are Tools for Data Management, Information Management, Knowledge Management • Several types of “registries” commonly used • The types of registries have related content, but extended and utilized in different ways • The registries vary according to: • intended purpose • granularity of contents • the level of semantics management Interoperability Standards at Levels of Syntax and Semantics

16. Software Component Registries ISO 11179Registries Common Content OASIS/ebXMLRegistries UDDIRegistries Common Content Common Content Common Content OntologicalRegistries Common Content Database Catalogs CASE Tool Repositories Common Content Common Content Types of Registries Interoperability Standards at Levels of Syntax and Semantics

17. Software Component Registries Common Content Example using "Country Name" as Common Content across Registry Types Database Catalogs Common Content ISO 11179Registries UDDIRegistries Common Content Common Content Country Name OASIS/ebXMLRegistries CASE Tool Repositories Common Content Common Content OntologicalRegistries Common Content Interoperability Standards at Levels of Syntax and Semantics

18. Name: Country Identifiers Context: Definition: Unique ID: 5769 Conceptual Domain: Maintenance Org.: Steward: Classification: Registration Authority: Others DataElementConcept Algeria Belgium China Denmark Egypt France . . . Zimbabwe Algeria Belgium China Denmark Egypt France . . . Zimbabwe L`Algérie Belgique Chine Danemark Egypte La France . . . Zimbabwe DZ BE CN DK EG FR . . . ZW DZA BEL CHN DNK EGY FRA . . . ZWE 012 056 156 208 818 250 . . . 716 Name: Context: Definition: Unique ID: 4572 Value Domain: Maintenance Org. Steward: Classification: Registration Authority: Others ISO 3166 3-Alpha Code ISO 3166 English Name ISO 3166 French Name ISO 3166 2-Alpha Code ISO 3166 3-Numeric Code "Country Name" in a 11179 Registry Data Elements Interoperability Standards at Levels of Syntax and Semantics

19. Software Component Registries Common Content Registries Address Different NeedsExample using "Country Name" as Common Content Database Catalogs Common Content ISO 11179Registries UDDIRegistries Table Column Data Element Common Content Common Content Business Specification Country Name OASIS/ebXMLRegistries CASE Tool Repositories XML Tag Attribute Common Content Common Content TermHierarchy OntologicalRegistries Business Object Common Content Interoperability Standards at Levels of Syntax and Semantics

20. Database Catalogs Common Content Types of Registries:Database Catalogs/Data Dictionaries/ Repositories • Registers schema, integrity & operational information • Includes all elements of database schemas: data elements, relations, integrity constraints • Emphasis on information required to make database systems work for queries, etc., not semantic management Interoperability Standards at Levels of Syntax and Semantics

21. Database Catalog Interoperability Standards at Levels of Syntax and Semantics

22. UDDIRegistries Common Content Types of Registries:Universal Description, Discovery, and Integration (UDDI) Registries • Registers Web-based Business Services • A White page directory of the business activities of firms • Emphasis on interface specifications Interoperability Standards at Levels of Syntax and Semantics

23. UDDI Registry <?xml version="1.0"?> <shipTo> <name>Alice Wilson</name> <street>161 North Street</street> <city>Happy Valley</city> <state>MO</state> <zip>63105</zip> <country code>USA</country code> </shipTo> Business-to-Business Interoperability Standards at Levels of Syntax and Semantics

24. CASE Tool Repositories Common Content Types of Registries:Case Tool (Encyclopedias/Repositories) • Registers data models and application program logic • Includes information needed to create a database and potentially the program code for a system, including database schemas • Emphasis not on semantic management Interoperability Standards at Levels of Syntax and Semantics

25. Case Tool Repository Interoperability Standards at Levels of Syntax and Semantics

26. OntologicalRegistries Common Content Types of Registries: Ontological Registries • Registers Concept Structures • Includes relations among concepts (subsumption, inheritance,…) and axioms for inference among concepts, e.g., temporal/spatial reasoning, etc. • Emphasis is on semantics Interoperability Standards at Levels of Syntax and Semantics

27. Concept Concept Concept Concept Geographic Area Geographic Sub-Area Country Country Identifier Country Name Country Code ISO 3166 2-Character Code ISO 3166 3- Character Code Short Name Long Name Mailing Address Country Name ISO 3166 3-Numeric Code FIPS Code Distributor Country Name Ontological Registry Interoperability Standards at Levels of Syntax and Semantics

28. Software Component Registries Common Content Types of Registries:Software Component Registries • Registers reusable software components built on specific vendor platforms such as EJB, COM, CORBA IDL etc. • Includes basic common elementary objects and object patterns • Emphasis on reusability of software component to build flexible and standardized business systems. Interoperability Standards at Levels of Syntax and Semantics

29. An Example of Software Component Registry Interoperability Standards at Levels of Syntax and Semantics

30. OASIS/ebXMLRegistries Common Content Types of Registries:OASIS/ebXML XML Registries • Registers XML Artifacts • Includes schemas and DTDs (XML schemata typically relate to a paper form, EDI document, or reporting requirement) • Emphasis on syntactic (structure) information Interoperability Standards at Levels of Syntax and Semantics

31. <?xml version="1.0"?> <shipTo > <name>Alice Wilson</name> <street>161 North Street</street> <city>Happy Valley</city> <state>MO</state> <zip>63105</zip> <country code>USA</country code> </shipTo> OASIS/ebXML XML Registry Repository VI304 Dollars X12 UnitPrice EDIFACT ListPrice Collaboration Partner #1 Collaboration Partner #2 Currency Schema or Template <Rep href= “http://www.disa.mil”>DISA</Rep> <ELEMENTrep= ‘DISA’name=‘Country’Biz =‘VI304’ > <Rep href= “http://www.disa.mil”>DISA</Rep> <ELEMENTrep= ‘DISA’name=‘CntryCode’Biz =‘VI304’ > Schema or Template XML Instance XML Instance <Country>JPN</Country> <CntryCode>JPN</CntryCode> Interoperability Standards at Levels of Syntax and Semantics

32. ISO 11179Registries Common Content Types of Registries:ISO 11179 Metadata Registries • Registers Data Elements, components of data elements and groups of data elements (e.g., country codes for customer place of residence) • Includes data element concepts, data elements (including representation), value domains, and (multiple) taxonomies • Emphasis on semantic information such as definitions of data elements and value meanings, and stewardship responsibilities Interoperability Standards at Levels of Syntax and Semantics

33. Data Element List – Address Group 33c Name Street Address City, State Postal Code Country ISO 11179 Registry <?xml version="1.0"?> <shipTo > <name>Alice Wilson</name> <street>161 North Street</street> <city>Happy Valley</city> <state>MO</state> <zip>63105</zip> <country code>USA</country code> </shipTo> Interoperability Standards at Levels of Syntax and Semantics