Naam van de presentatie OTB Research Institute for Housing, Urban and Mobility Studies GML, NEN3610 and TOP10NL 4 th GML Relay (Emmen) Wilko Quak

OTB Research Institute for Housing, Urban and Mobility Studies GML, NEN3610 and TOP10NL Overview NEN3610 and its history TOP10NL – a model on top of NEN3610 Transforming the model to GML Questions

OTB Research Institute for Housing, Urban and Mobility Studies GML, NEN3610 and TOP10NL History of NEN3610 Originated by Ravi (Network Organization for Geo- Information) First base model in 1992 Exchange format NEN1878

OTB Research Institute for Housing, Urban and Mobility Studies GML, NEN3610 and TOP10NL 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

OTB Research Institute for Housing, Urban and Mobility Studies GML, NEN3610 and TOP10NL 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.

OTB Research Institute for Housing, Urban and Mobility Studies GML, NEN3610 and TOP10NL NEN3610 – base class: GeoObject Unique nationwide Identifier Temporal attributes can be used for incremental updates Almost all attributes are optional

OTB Research Institute for Housing, Urban and Mobility Studies GML, NEN3610 and TOP10NL 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’)

OTB Research Institute for Housing, Urban and Mobility Studies GML, NEN3610 and TOP10NL NEN3610 the UML Model

OTB Research Institute for Housing, Urban and Mobility Studies GML, NEN3610 and TOP10NL 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

OTB Research Institute for Housing, Urban and Mobility Studies GML, NEN3610 and TOP10NL 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)

OTB Research Institute for Housing, Urban and Mobility Studies GML, NEN3610 and TOP10NL Overview NEN3610 and its history TOP10NL – a sector model in NEN3610 Transforming the model to GML Conclusions

OTB Research Institute for Housing, Urban and Mobility Studies GML, NEN3610 and TOP10NL Base model and sector models National standard Sector specific Organisation specific NEN3610 IMRO IMWA RWS IMKICH TOP10NL IM.. Exchange International standard ISO 191XX OGC

OTB Research Institute for Housing, Urban and Mobility Studies GML, NEN3610 and TOP10NL 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

OTB Research Institute for Housing, Urban and Mobility Studies GML, NEN3610 and TOP10NL 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.

OTB Research Institute for Housing, Urban and Mobility Studies GML, NEN3610 and TOP10NL 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!

OTB Research Institute for Housing, Urban and Mobility Studies GML, NEN3610 and TOP10NL 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

OTB Research Institute for Housing, Urban and Mobility Studies GML, NEN3610 and TOP10NL TOP10NL – The first sector-model TOP10NL is a national 1 : 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.

OTB Research Institute for Housing, Urban and Mobility Studies GML, NEN3610 and TOP10NL TOP10NL – the complete model

OTB Research Institute for Housing, Urban and Mobility Studies GML, 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)

OTB Research Institute for Housing, Urban and Mobility Studies GML, NEN3610 and TOP10NL Overview NEN3610 and its history TOP10NL – a model in the NEN3610 family Transforming the models to GML Questions

OTB Research Institute for Housing, Urban and Mobility Studies GML, NEN3610 and TOP10NL Automatic Translation of UML model Configuration (XML) GML Application Schema (XML Schema) ShapeChange (Java, Servlet) UML Application Schema (XMI) Configuration (XML) GML Application Schema (XML Schema) ShapeChange (Java program) UML model Encoding Rules Guidelines

OTB Research Institute for Housing, Urban and Mobility Studies GML, NEN3610 and TOP10NL 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

OTB Research Institute for Housing, Urban and Mobility Studies GML, NEN3610 and TOP10NL 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

OTB Research Institute for Housing, Urban and Mobility Studies GML, NEN3610 and TOP10NL 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.

OTB Research Institute for Housing, Urban and Mobility Studies GML, NEN3610 and TOP10NL 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

OTB Research Institute for Housing, Urban and Mobility Studies GML, NEN3610 and TOP10NL 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

OTB Research Institute for Housing, Urban and Mobility Studies GML, NEN3610 and TOP10NL Questions?