Transcript Schneider_pres

Coordination of geographic information and geographic information systems
Metadata
www.e-geo.ch
COGIS
May 03
Slide 2
NSDI
Political
economical profit
added value for:
• public sector
(Federal, Cantons,
Communes)
• organizations
(private sector,
science etc.)
• General public
Impact
Easy available
Optimal offer
wider use
Favorable prices
Transparency
National Spatial Data Infrastructure (NSDI)
Basic Geoinformation
Basic Geoservices
Metadata
Technical
infrastructure
e-geo.ch
Network
Standards
Legal
bases
COGIS
Education
Training
Research
Strategy for distribution and pricing
May 03
Slide 3
Metadata is a part of the NSDI
National Spatial Data Infrastructure (NSDI)
Basic Geoinformation
Technical
infrastructure
Basic Geoservices
Metadata
Education
Training
e-geo.ch
Network
Research
Standards
Legal
bases
Strategy for distribution and pricing
COGIS
May 03
Slide 4
Outline
• geocat.ch
– Concept
– Timetable
– Pilot application
• The metadata model for Switzerland
– GeoMeta, the swiss profile of ISO 19115
– Our model-based approach
– Our experiences with the implementation
• Catalog gateway protocol
– Goals
– Overview
– Query language
COGIS
May 03
Slide 5
geocat.ch concept (1)
• The geocat.ch project wants to set up a metadata catalogue for
GI
• Geocat.ch will permit to add, edit, manage and to search for
metadata on the Internet
• It will be realised as a framework of distributed metadata and
applications in a federated and heterogeneous infrastructure.
Service de découverte
geocat.ch
COGIS
May 03
Slide 6
geocat.ch concept (2)
user
uses
User Interface /
Discovery Service
posts a query to
Directory of
Servers
(Registriy)
Catalog
Gateway
searches multiple
catalog
administrator
maintains
manages
Catalog
Server(s)
manages
gateway
manager
deliever entries of
has reference to
metadata
contributor
complies
Metadata
Spatial Data
Source: GSDI Cookbook, Version 1.1
COGIS
May 03
Slide 7
geocat.ch concept (3)
2 type of database are connected:
– One central database: the geocat.ch database, which is accessible
to the geocat.ch search application
– Distributed databases, which are connected to the Catalog
Gateway of the geocat.ch search application
3 partnership possibilities exist for the producer of data:
– Partner A: they manage their metadata directly in the central
database
– Partner B: they manage their metadata in their own database. To
make their metadata accessible to the geocat.ch search
application, they use the import/export tool to put them in the
central database.
– Partner C: they manage their metadata in their own database. The
metadata is accessible, because the database is connected to the
Catalog Gateway
COGIS
May 03
Slide 8
Schedule of geocat.ch
Model
June to
December 2001
Study of ISO 19115 and proposal of
a profile for Switzerland
January to
march 2002
Elicitation to 120 organisations,
cantons and offices, 53 Reponses
April 2002
Workshop: presentation of the
results of the elicitation
Application
March to august
2002
A requirements specification is made with a
group of 20 people (cantons, offices,
organisation)
November 2002
Collaboration with Eurogeographics
December 2002
Choice of the producer and begin of the
application development
May 2003
Pilot application is available
May 2003
A new draft of a ISO 19115 profile
for Switzerland
June 2003 to ?
Begin of a RFC (request for
comments) and the standardisation
process
September 2003
Catalog Gateway protocol will be defined
December 2003
Final application will be available
COGIS
May 03
Slide 9
Pilot application geocat.ch
COGIS
May 03
Slide 10
Outline
• geocat.ch
– Concept
– Timetable
– Pilot application
• The metadata model for Switzerland
– GeoMeta, the swiss profile of ISO 19115
– Our model-based approach
– Our experiences with the implementation
• Catalog gateway protocol
– Goals
– Overview
– Query language
COGIS
May 03
Slide 11
GeoMeta the Swiss profile
• Based on ISO 19115
• Additional requirements were derived from an analysis of
existing data catalogs (SIK-GIS and CDS)
• ISO Standard covered most of these requirements
• Swiss profile as presented at the workshop on May 22, 2002 in
Bangkok:
– legal information is an additional metadata component
– Multilingual support is essential (should be normative in ISO
19115)
– Several components and classes are not needed
• Since Bangkok workshop:
– Model revised with the results from the elicitation and the
FDIS version
COGIS
May 03
Slide 12
Experience with implementation of GeoMeta (I)
ISO approach of Profiles
Swiss approach
– Profiles are reductions of a
general model
– This approach proved to be not
feasible in our case
– Local models are not necessary
based on common model
– Comprehensive Swiss profile is an
extension of the core profile
– All additional models are derived
from the same base model
Comprehensive
Core
Comprehensive
Core
Local
metadatamodel
Local
metadatamodel
Local
metadatamodel
COGIS
Local
metadatamodel
May 03
Slide 13
Experience with implementation of GeoMeta (II)
Responsible party can not be modeled as data type.
– A specific party is responsible for several datasets
– It can have different roles
– Should only be stored and maintained once
Streetmap: MD_Identification
Basemap: MD_Identification
role: custodian
Basemap-Metadata: MD_Metadata
role: owner
role: pointOfContact
role: owner
Rivermap: MD_Identification
Mary: CI_ResponsibleParty
John: CI_ResponsibleParty
Individual Name: Mary Miller
Organisation Name: Navtec
Individual Name: John Davis
Organisation Name: SwissTopo
COGIS
role: distributerContact
May 03
Slide 14
From UML to XML-Schema
•
•
•
•
•
•
•
•
External classes were moved into 19115 package
All other packages were deleted
Multiplicity removed from attribute name and defined as a
tagged value
Data types reviewed and stereotype changed where needed to
fit the semantics predefined by UML
Export from Rational Rose to XMI
Import into UML/INTERLIS-Editor
Additional data type definitions
Export to XML-Schema
COGIS
May 03
Slide 15
Additional data type definition: Example
COGIS
May 03
Slide 16
Outline
• geocat.ch
– Concept
– Timetable
– Pilot application
• The metadata model for Switzerland
– GeoMeta, the swiss profile of ISO 19115
– Our model-based approach
– Our experiences with the implementation
• Catalog gateway protocol
– Goals
– Overview
– Query language
COGIS
May 03
Slide 17
Goals of the protocol
• A catalog gateway protocol needs to be defined :
– to manage a connection between the gateway application (client)
and an external server;
– to be able to send a query from the client to the server;
– for the client to be able to receive query results from the server.
• This query mechanism must be :
– independent of the platform/system/vendor of both the client and
the server;
– independent of the programming language used on either side;
– independent of the network protocol used between the client and
the server;
• The protocol must support multiple languages and spatial query
criteria
• The protocol must be relatively cheap to implement
COGIS
May 03
Slide 18
Overview of the protocol
geocat.ch
Server
OverviewQuery
OverviewAnswer
DetailQuery
DetailAnswer
• The OpenGIS Catalog Service
and the Z39.50 protocols were
considered to be too general
for a cost effective
implementation.
• SOAP (Simple Object Access
Protocol) was chosen. It’s an
XML based wrapping
structure, like the postal
services which use an
envelope for letters that
contain questions and
answers.
COGIS
May 03
Slide 19
The query language of the protocol
Query language
Description
Price of the implementation
XQuery
new and still unstable
specification for the
query of XML
structures
too expensive for relational
databases
SQL
Standard query
too expensive for XML
language for relational
structures
databases (suggested
by the OpenGIS Catalog
Service specifications)
geocat.ch
solution
Only the needed
Cheap for the relational
functions exist
databases and the XML
The query attributes are structures
predefined
COGIS
May 03
Slide 20
The geocat.ch query language
solution example
COGIS
May 03
Slide 21
Conclusion
• The ISO 19115 standard covered most of our
requirements
• A model-based approach : Comprehensive Swiss
profile is an extension of the core profile
• To realise a framework of distributed metadata and
applications in a federated and heterogeneous
infrastructure, a catalog gateway protocol is necessary
COGIS
May 03
Slide 22