Interoperability

A simple case for standards

Kim Finney

JCADM – Rome 2007

Data Exchange Scenario

Instruments/Measurements

Observations

Local data store

computer to computer communication

Data Exchange ScenarioWhich attributes can be considered to be capturing the same information ?

CTD Measurements Seal Observations

Project nameCruiseInstrument typePrincipal Investigator nameQuality control flagsDepth/Temperature valuesDepth salinity valuesLatitudeLongitude

ShipVoyageEquipmentOwnerDepthsSalinity/Temp/OxygenStart positionStop position

Species AbundanceAgeWeightSexLocation

Mammal typeOccurrenceSizeAgeMale/FemaleRegion

Data Exchange ScenarioNote that the “data type” of the values can also be different?

Seal Observations

Species = Leptonychotes weddellii Abundance = 66Age = five yrsWeight = 65Sex = 20F30MLocation = CS

Mammal type = Weddell sealOccurrence = 67Size = 56Age = 4Male/Female = 5:1Region = 151 10 E 70 12 S

Data Exchange ScenarioHow do we know what units of measure, codes, CRS have been used ?

Seal Observations

Species = Leptonychotes weddellii Abundance = 66 (INDIVIDUALS)Age = five yrs old (AV. YEARS)Weight = 65 (AV. Kg)Sex = 20F30M (TOTAL OF EACH)Location = CS (PLACE NAME CODE)

Mammal type = Weddell seal pupsOccurrence = 67 (INDIVIDUALS)Size = 56 (cm AV. LENGTH)Age = 4 (AV. MONTHS)Male/Female = 5:1 (RATIO)Region = 151 10 E 70 12 S (LAT/LONG CRS)

Data Exchange ScenarioEncodings and formatting patterns can also be very different ?

Seal Observations

L. Wedelli, 66, 5years, 65, 20F30M, CSL. Wedelli, 23, 2years, 64, 22F30M, CSL. Wedelli, 44, 5years, 54, 23F30M, CSL. Wedelli, 23, 3years, 56, 24F30M, CSL. Wedelli, 109, 2years, 68.4, 19F30M, CS

Weddell seal67 64 56 56 4 4 5:1 4:1151 10 E 70 12 S 151 10 E 70 12 S

Semantics

• Collaborators need to be able to agree on:

– The definitions of the real-world objects to be exchanged

Weddell Seal pups ?

Seals ?

Marine mammals ?

Leptonychotes weddellii ?

All of the above ?

Including attributes

– How to model the characteristics of these real-world objects

-genus : char-species : char-common name : char-observation_date : char-Id : int-sex : char-Weight : decimal-Age : decimal

Taxon_Specimen

Synonyms

Observation_ProcedureLocation

Encoding

– How to encode representations of these real-world objects to exchange them in cyberspace so that machines – not just humans can interpret their meaning.

<taxon_specimen> <genus>Leptonychotes</genus> <species> weddellii </species> <common_name>weddell seal</common_name> <observation_date>12Jan06</observation_date> <id>123</id> <sex>F</sex> <weight uom="http://UnitsDictionary.xml#Kg>76 </weight> <age uom="http://UnitsDictionary.xml#yrs>8</age></taxon_specimen>

Reference Systems

• Standard ways of representing real world object geometry or at least declare reference systems.

e.g. Swath data

e.g. Radar data

– Declaration of units of measure– Standard ways of representing location

Controlled Vocabularies• Dictionaries of terms

– Term, textual definition– Ranges, permissible codes, units of measure

(optional)

• Ontologies– As above but includes relationships between

terms and rules (axioms).

Ontologies• Many definitions

– A shared and common understanding of a domain that can be communicated between people and across application systems (Gruber, 1993).

Classes or concepts =>

Sub-classes =>

Properties or slots =>

individualclass is instance of

Sub-class classis part of

individual propertyhas value of

class propertyrestricts

Relationships

Semantic Interoperability

Data Data

Heterogeneous data sources

Common patterns

web service web service web service

DiscoverQuery

IntegrateDownloadVisualise

Filter

ServiceRegistry

publishfind

bindbindbind

Source A Source B Source C

SymbologyCatalogue

use

use

FeatureCatalogue

SemanticsEncodingsSymbolsProtocols

Common PatternsFeature Catalogue

• Feature Catalogue– Stores definitions of features (objects) & information about their

attributes & relationships between features (semantics).

CTD Profile {Feature}PositionBottom DepthDepthParameter

Feature Attributes

Project {Feature}Project NameProject Description

Platform {Feature}Platform TypePlatform Name

Procedure {Feature}Instrument TypeProcessing Method

Platform

CTD Profile

Procedure

Project

ownedBy hostedBy

generatedBy

Common PatternsSymbology Catalogue

• Symbology Catalogue– Stores portrayal rules and symbols for displaying features (objects).– Associates features (e.g. CTD) with symbol(s) which can have scale and

other styling dependencies.

Common PatternsEncodings (syntax + semantics)

GML- An Open Geospatial Consortium

(OGC) Standard.

- Tuned for representing geometry

and topologies.

- Widely adopted to exchange and

manipulate data with a spatial

component.

- 600 page specification.

- Syntax makes no allowance for

incorporating other languages, no

axioms supported.

- All derivatives of this language are

called Application Profiles.

<Whales> <Whale> <gml:name>Minke</gml:name> <gml:whaletype> <gml:String srsName="EPSG:4326"> <gml:coordinates> 0,5.0 20.6,10.7 80.5,60.9 </gml:coordinates> </gml:String> </gml:whaletype> <classification>marinemammal</classification> <number>CAAB Code 34567</number> </whale></whales>

WMSmaps

WFSfeature data

WCScoverage data

Common PatternsEncodings + Protocol

• OGC (GML-based) web service protocols

– Commonly used to encode and send data between systems

getCapabilities() describeFeature() getFeature()

Supports a few well known service functions including:

CTD GML WFS Encoding

<IMOS:Dataset>{include and import statements for re-using other GML-based ontology elements}<IMOS:ObservationCollection> {encompasses all deployments and observation members}{properties describing bounding box, time, etc for all deployments}

<IMOS:Observation> {first observation member}{project, platform, location, time, procedure, composite phenomena properties}

<IMOS:FeatureofInterest> {CTD feature}{CTD specific properties encoded in a specialised CSML Profile Feature}</IMOS:FeatureofInterest> <IMOS:Result> {CTD data values}

<IMOS:domainSet>{CTD domain properties and values encoded in a specialised CSML Profile Coverage}

</IMOS:domainSet><IMOS:rangeSet>

{CTD range properties and values encoded in a specialised CSML Profile Coverage}</IMOS:rangeSet>

</IMOS:Result></IMOS:Observation><IMOS:Observation> {second observation member – pattern repeats}

…………………………

</IMOS:Observation></IMOS:ObservationCollection></IMOS:Dataset>