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GML, NEN3610 and TOP10NL. 4 th GML Relay (Emmen). Wilko Quak. Overview. NEN3610 and its history TOP10NL – a model on top of NEN3610 Transforming the model to GML Questions. History of NEN3610. Originated by Ravi (Network Organization for Geo-Information) First base model in 1992

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gml nen3610 and top10nl

GML, NEN3610 and TOP10NL

4th GML Relay (Emmen)

Wilko Quak

overview
Overview
  • NEN3610 and its history
  • TOP10NL – a model on top of NEN3610
  • Transforming the model to GML
  • Questions

GML, NEN3610 and TOP10NL

history of nen3610
History of NEN3610
  • Originated by Ravi (Network Organization for Geo-Information)
  • First base model in 1992
  • Exchange format NEN1878

GML, NEN3610 and TOP10NL

new nen3610 work started in 2003
New NEN3610 (work started in 2003)

Prerequisites:

  • Based on International Standards (ISO, OGC)
  • Backwards compatible with old NEN3610
  • Should be a base for the exchange of all geo-data in the Netherlands (Top-Down approach)
  • Extensible

GML, NEN3610 and TOP10NL

nen3610 specifications
NEN3610 specifications
  • Nationwide unique identifiers
  • Temporal model useful for change only updates
  • Fully described in UML
  • GML Application Schema is automatically derived from the UML model.
  • The model is not complete by itself; it is a starting point for sectors that should make a Sector Model
  • One base class ‘GeoObject’ and about a dozen subclasses.

GML, NEN3610 and TOP10NL

nen3610 base class geoobject
NEN3610 – base class: GeoObject
  • Unique nationwide Identifier
  • Temporal attributes can be used for incremental updates
  • Almost all attributes are optional

GML, NEN3610 and TOP10NL

nen3610 subclasses
NEN3610 – subclasses
  • Road
  • Water
  • Railroad
  • Terrain – area with specific landuse
  • Building
  • Construction – bridges, telephone poles etc.
  • Dyke – very important in the Netherlands
  • Cables – underground
  • RegistrationalArea – province, municipality boundary
  • GeographicArea – areas with vague boundaries (like the ‘Lake District’ or ‘the Alps’)

GML, NEN3610 and TOP10NL

nen3610 the uml model
NEN3610 the UML Model

GML, NEN3610 and TOP10NL

nen3610 temporal model
NEN3610 – temporal model
  • Four temporal attributes for version management and incremental updates.
  • objectBeginTime and objectEndTime indicate the lifetime of an object.
  • If an attribute changes a new version is shipped with a new versionBeginTime.
  • An object is deleted by shipping it with a non null objectEndTime.
  • Two temporal attributes for when the object changed in the real world: beginTime and endTime

GML, NEN3610 and TOP10NL

advantages of a nationwide base model
Advantages of a nationwide base model

+ Shared definitions

+ One shared temporal model for all data in the Netherlands

- To keep everybody happy almost all attributes are optional and definitions very vague

+ A published base model is a good starting point for sector models (even if they do not agree with the model)

GML, NEN3610 and TOP10NL

overview1
Overview
  • NEN3610 and its history
  • TOP10NL – a sector model in NEN3610
  • Transforming the model to GML
  • Conclusions

GML, NEN3610 and TOP10NL

base model and sector models

IM . .

TOP10NL

IMKICH

RWS

IMWA

IMRO

Base model and sector models

International standard

OGC

ISO 191XX

NEN3610

National standard

Exchange

Sector specific

Organisation specific

GML, NEN3610 and TOP10NL

making a sector model
Making a sector model

Sectors that use NEN3610 should choose the most applicable class in NEN3610 and extend it.

If no applicable class is found GeoObject can be extended

How to extend:

  • Extending by subclass
  • Extending by pattern

GML, NEN3610 and TOP10NL

extension by subclass
Extension by Subclass

Create subclass

  • add attributes
  • restrict attributes

An extension should not

contradict with its base class.

Any instance of the subclass

must be a valid instance of the

superclass.

GML, NEN3610 and TOP10NL

multiple inheritance
Multiple Inheritance
  • If the original hierarchy has more than one level subclassing might result in a multiple inheritance hierarchy.

Keep base hierarchy as flat as possible!

GML, NEN3610 and TOP10NL

extension by pattern
Extension by Pattern
  • Copy class and attributes of all superclasses
  • add new attributes
  • delete unused attributes (when they were optional)
  • Results in a new stand-alone UML model

GML, NEN3610 and TOP10NL

top10nl the first sector model
TOP10NL – The first sector-model
  • TOP10NL is a national 1 : 10 000 topographic dataset of the Netherlands provided by the Dutch Kadaster
  • Relatively easy because TOP10NL had a lot of influence on the NEN3610 model
  • Extension by subclass
    • Multiple Inheritance avoided by making TOP10Object an attribute of every subclass.

GML, NEN3610 and TOP10NL

top10nl the complete model
TOP10NL – the complete model

GML, NEN3610 and TOP10NL

lessons learnt from modeling nen3610 and top10nl
Lessons learnt from modeling NEN3610 and TOP10NL
  • If you want to understand your own data try to make a model that fits.
  • Keep your model as simple as possible
  • Make a 1-level hierarchy at most
  • Give definitions of all classes and attributes (preferably also in English)

GML, NEN3610 and TOP10NL

overview2
Overview
  • NEN3610 and its history
  • TOP10NL – a model in the NEN3610 family
  • Transforming the models to GML
  • Questions

GML, NEN3610 and TOP10NL

automatic translation of uml model
Automatic Translation of UML model

UML

UML

Application

Guidelines

Schema

model

(XMI)

Encoding Rules

ShapeChange

ShapeChange

(Java, Servlet)

(Java program)

Configuration

Configuration

(XML)

(XML)

GML

GML

Application

Application

Schema

Schema

(XML Schema)

(XML Schema)

http://www.interactive-instruments.de/ugas/

GML, NEN3610 and TOP10NL

consequences of automatic translation
Consequences of Automatic Translation

Because the GML Schema depends for 100% on the UML

model every choice you make in UML is directly reflected

in GML:

  • You only have to worry about the UML model
  • Extension by pattern gives different schemas than extension by subclass
  • Every typo is a bug

GML, NEN3610 and TOP10NL

extension by subclass consequences for xml schema
Extension by Subclass: Consequences for XML Schema
  • The resulting GML lives in two nameSpaces (nen3610 and top10nl)
  • The sector model includes the definition of the base model and only describes the changes.
  • Every extension results in a substitutionGroup in the application schema.
  • Automatic translation of restrictions from UML is tricky. Manual post-processing of the schema is sometimes needed.
  • Some restrictions cannot be expressed in XML-Schema

GML, NEN3610 and TOP10NL

nen3610 gml application schema
NEN3610 – GML application schema
  • The NEN3610 UML Model has been automatically converted to a GML application schema (NEN3610.XSD) This software was modified to partly overcome the problems with restrictions in subclasses
  • TOP10NL can include the NEN3610.XSD from their own schema.

GML, NEN3610 and TOP10NL

extension by pattern consequences for xml schema
Extension by pattern: Consequences for XML Schema
  • Simple document structure
  • It is not clear from the schema that the sector model is an extension of the base model

GML, NEN3610 and TOP10NL

gml design choices in top10nl what s your opinion
GML design choices in TOP10NL (what’s your opinion?)
  • Extension by subclass resulting in many substitutionGroups.
  • lang=“nl” attribute to encode language of geographic names. (this should be part of GML).
  • Use of objectBeginTime and objectEndTime enables incremental updates
  • Choice of UTF8 as character encoding: Reli?34f Ge?34lectrificeerd

GML, NEN3610 and TOP10NL

questions
Questions?

GML, NEN3610 and TOP10NL

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