Standard TypeName and mapping to programming language

[desruisseaux]

ISO 19157 defines some properties like DQM_Measure.valueType of type TypeName (from ISO 19103) with the following documentation:

Shall be one of the data types defined by ISO/TS 19103:2005.

It would be convenient to have a consolidated list of main types, together with proposed mapping to Java or Python classes. A proposal is shown in the table below. This proposal uses an "OGC" namespace by consistency with data type URN standard value 1.1 in OGC schemas, which defines standard types like below:

• urn:ogc:def:dataType:OGC:1.1:boolean
• urn:ogc:def:dataType:OGC:1.1:nonNegativeInteger
• urn:ogc:def:dataType:OGC:1.1:string
• urn:ogc:def:dataType:OGC:1.1:anyURI

By extension, proposal of standard TypeName values in GeoAPI:

Scoped type name	Java class	Python class
OGC:Boolean	java.lang.Boolean	int
OGC:Integer	java.lang.Integer	int
OGC:Real	java.lang.Double	float
OGC:Decimal	java.math.BigDecimal	float
OGC:CharacterString	java.lang.String	str
OGC:FreeText	org.opengis.util.InternationalString	str
OGC:PT_Locale	java.util.Locale
OGC:DateTime	java.time.ZonedDateTime
OGC:URI	java.net.URI	str
OGC:Matrix	org.opengis.referencing.operation.Matrix	np.ndarray
OGC:Coverage	org.opengis.coverage.Coverage	Coverage
OGC:MD_Metadata	org.opengis.metadata.Metadata	Metadata

An open question is how to manage collections. ISO 19157 has the following policy:

• ValueStructure set to bag, set or sequence.
• TypeName with the type of elements in the collection.

If we want to avoid ValueStructure in GeoAPI (see #74), where to put this information?