Overview dataSource Representing dynamic features

Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved. 169 element name=dataSource type=gml:StringOrRefType element name=dataSourceReference type=gml:ReferenceType The remote link attributes of the gml:dataSource element have been deprecated along with its current type. To refer to a remote data source, use the remote link attributes of gml:dataSourceReference instead. EXAMPLE A human observer or an in situ sensor.

14.5.3 Dynamic properties

A convenience group gml:dynamicProperties is defined as follows: group name=dynamicProperties sequence element ref=gml:validTime minOccurs=0 element ref=gml:history minOccurs=0 element ref=gml:dataSource minOccurs=0 element ref=gml:dataSourceReference minOccurs=0 sequence group This allows an application schema developer to include dynamic properties in a content model in a standard fashion. The gml:validTime property is specified in 14.2.1.3. The other properties are specified elsewhere in 14.5.

14.5.4 DynamicFeature

States are captured by time-stamped instances of a feature. gml:DynamicFeature implements DynamicFeature as shown in D.3.11 and is declared as follows: element name=DynamicFeature type=gml:DynamicFeatureType substitutionGroup=gml:AbstractFeature The content model extends the standard gml:AbstractFeatureType with the gml:dynamicProperties model group: complexType name=DynamicFeatureType complexContent extension base=gml:AbstractFeatureType group ref=gml:dynamicProperties extension complexContent complexType Each time- stamped instance represents a ‗snapshot‘ of a feature. The dynamic feature classes will normally be extended to suit particular applications. A dynamic feature bears either a time stamp or a history. NOTE A history consists of a set of gml:AbstractTimeSlices and such time slices may contain any time varying properties. We might for example use such a mechanism to describe a feature with one property that varies in time.

14.5.5 DynamicFeatureCollection

gml:DynamicFeatureCollection implements DynamicFeatureCollection as shown in D.3.11 and is declared as follows: element name=DynamicFeatureCollection type=gml:DynamicFeatureCollectionType substitutionGroup=gml:DynamicFeature 170 Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved. The content model extends gml:DynamicFeatureType with the gml:dynamicMembers property: complexType name=DynamicFeatureCollectionType complexContent extension base=gml:DynamicFeatureType sequence element ref=gml:dynamicMembers sequence extension complexContent complexType element name=dynamicMembers type=gml:DynamicFeatureMemberType complexType name=DynamicFeatureMemberType complexContent extension base=gml:AbstractFeatureMemberType sequence element ref=gml:DynamicFeature minOccurs=0 maxOccurs=unbounded sequence attributeGroup ref=gml:AssociationAttributeGroup extension complexContent complexType A gml:DynamicFeatureCollection is a feature collection that has a gml:validTime property i.e. is a snapshot of the feature collection or which has a gml:history property that contains one or more gml:AbstractTimeSlices each of which contain values of the time varying properties of the feature collection. Note that the gml:DynamicFeatureCollection may be one of the following: 1. A feature collection which consists of static feature members members do not change in time but which has properties of the collection object as a whole that do change in time 6 . EXAMPLE 1 A Train: The Train is a feature collection. The position and speed of the train are time varying and could be captured in the history of the Train. The featureMembers of the Train are the individual cars including the locomotive. The properties of the cars are static such as the position of the car in the train we ignore any re-organization of the train in this example, the cargo, the make of the car and its type e.g. grain car, oil car etc.. 2. A feature collection which consists of dynamic feature members the members are gml:DynamicFeatures but which also has properties of the collection as a whole that vary in time.