Interoperability Standards at Levels of Syntax and Semantics Presented by Eliot Christian at the...

Interoperability Standards at Levels of Syntax and

Semantics

Presented by Eliot Christian <[email protected]>

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

World Meteorological Organizations (WMO)Observing and Information Systems Department

WMO Information System (WIS)

Interoperability Standards at Levels of Syntax and Semantics 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)


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


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,


Comparing ASN.1 and XML Syntactic Mechanisms

ASN.1 XML

syntax description specification schema

structure mechanism

start-position and length

mark-up with start-end tags

atomic element bit character

encoding mechanism

encoding rules (basic, packed...)

Unicode filter(ISO 8859-1, UTF-8 ...


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


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"


Example: Common Alerting Protocol

Uses 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


Standards-based Interoperability at the Level of Semantics


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")


Example: CAP Data Dictionary ElementName

Context. Class.Attribute. Represent-ation

Definition and (Optionality) Notes or Value Domain

alert cap.alert.group

The container for all component parts of the alert message (REQUIRED)

(1) Surrounds CAP alert message sub-elements.(2) MUST include the xmlns attribute referencing the CAP URI as the namespace, e.g.: <cap:alert xmlns:cap="urn:oasis:names:tc:emergency:cap:1.1"> [sub-elements] </cap: alert>(3) In addition to the specified sub-elements, MAY contain one or more <info> blocks.

identifier cap.alert.identifier

The identifier of the alert message (REQUIRED)

(1) A number or string uniquely identifying this message, assigned by the sender(2) MUST NOT include spaces, commas, or restricted characters (< and &)

sender cap.alert.sender.identifier

The identifier of the sender of the alert message (REQUIRED)

(1) Identifies the originator of this alert. Guaranteed by assigner to be unique globally; e. g., may be based on an Internet domain name(2) MUST NOT include spaces, commas, or restricted characters (< and &)

sent cap.alert.sent.time

The time and date of the origination of the alert message (REQUIRED)

The date and time is represented in [dateTime] format (e.g., "2002-05-24T16:49:00-07:00" for 24 May 2002 at 16: 49 PDT).

status cap.alert.status.code

The code denoting the appropriate handling of the alert message (REQUIRED)

Code Values:“Actual" Actionable by all targeted recipients“Exercise" Actionable only by designated exercise participants; exercise identifier should appear in <note>“System" For messages that support alert network internal functions.“Test" Technical testing only, all recipients disregard


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


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


Using Registries to Manage

Data / Metadata Syntax and Semantics


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


Types of Registries

Common Content

OASIS/ebXMLRegistries

Common Content

ISO 11179Registries

Common Content

OntologicalRegistries

Common Content

DatabaseCatalogs

Common Content

CASE ToolRepositories

Common Content

UDDIRegistries

SoftwareComponentRegistries

Common Content


Example using "Country Name" as Common Content across Registry Types

Common Content


Common Content

ISO 11179Registries

Common Content


Common Content


Common Content

UDDIRegistries

CountryName


Common Content

Common Content

DatabaseCatalogs


Data ElementsISO 3166

English NameISO 3166

3-Numeric CodeISO 3166

2-Alpha CodeISO 3166

French NameISO 3166

3-Alpha Code

DZ

BE

CN

DK

EG

FR

. . .

ZW

012

056

156

208

818

250

. . .

716

Algeria

Belgium

China

Denmark

Egypt

France

. . .

Zimbabwe

Name:Context:Definition:Unique ID: 4572Value Domain:Maintenance Org.Steward:Classification:Registration Authority:Others

L`Algérie

Belgique

Chine

Danemark

Egypte

La France

. . .

Zimbabwe

DZA

BEL

CHN

DNK

EGY

FRA

. . .

ZWE

"Country Name" in a 11179 Registry

Algeria

Belgium

China

Denmark

Egypt

France

. . .

Zimbabwe

Name: Country IdentifiersContext:Definition:Unique ID: 5769Conceptual Domain:Maintenance Org.:Steward:Classification:Registration Authority:Others

DataElementConcept


Registries Address Different NeedsExample using "Country Name" as Common Content

Common Content


Common Content

ISO 11179Registries

Common Content


Common Content


Common Content

UDDIRegistries

CountryName

DataElement

XML Tag

TermHierarchy

Attribute

BusinessSpecification

TableColumn


Common Content

Common Content

DatabaseCatalogs

BusinessObject


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

Common Content

DatabaseCatalogs


Database Catalog


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

Common Content

UDDIRegistries


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


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

Common Content



Case Tool Repository


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

Common Content



Ontological Registry

Concept Concept

ConceptConcept Geographic Area

Geographic Sub-Area

Country

Country Identifier

Country Name Country Code

Short Name ISO 31662-Character

Code

ISO 31663- Character

Code

Long Name

DistributorCountry Name

Mailing AddressCountry Name ISO 3166

3-Numeric CodeFIPS Code


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.


Common Content


An Example of Software Component Registry


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

Common Content



OASIS/ebXML XML Registry

<Country>JPN</Country>

Repository

VI304

ListPriceCurrency

Dollars

XML Instance

UnitPrice

XML Instance

<CntryCode>JPN</CntryCode>

CollaborationPartner #1

X12

EDIFACT

<Rep href= “http://www.disa.mil”>DISA</Rep>

<ELEMENT rep= ‘DISA’ name=‘Country’ Biz =‘VI304’ >


<ELEMENT rep= ‘DISA’ name=‘Country’ Biz =‘VI304’ >

Schema or Template<Rep href= “http://www.disa.mil”>DISA</Rep>

<ELEMENT rep= ‘DISA’ name=‘CntryCode’ Biz =‘VI304’ >


<ELEMENT rep= ‘DISA’ name=‘CntryCode’ Biz =‘VI304’ >

Schema or Template

CollaborationPartner #2

<?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>


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

Common Content

ISO 11179Registries


Data Element List – Address Group

<?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>

ISO 11179 Registry

33c

NameStreet AddressCity, State Postal CodeCountry

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