SWIM Supporting Material

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Requirement

Title

Use of data types

Identifier

SWIM-INFO-012

Requirement

An information definition shall use basic data types for its data concepts that are compatible with the system of basic data types used in the AIRM.

Rationale

Compatibility between data types facilitates interoperability. Agreement on a reference set of basic data types facilitates the understanding of the data types used in an information definition. This, in turn, facilitates the correct translation of data types between various implementations.

Verification

Consistency

Examples/Notes

Note: The AIRM imports ISO 19103 [RD 5] for its basic data types. These include: Boolean, CharacterString and Real.

Note: The XML Schema Definition Language supports, inter alia, Boolean, string and real.

Level of Implementation

Mandatory

Guidance

Basic data types include:

  • booleans
  • strings
  • numbers such as reals and decimals
  • dates

The AIRM import ISO 19103:2005 - Geographic information — Conceptual schema language as the reference for its basic types. In effect, this requirement asks that information definitions use a set of basic data types that are compatible with ISO 19103:2005. UML examples of ISO 19103 are given below.

Compatible is defined in the dictionary as "able to exist or occur together without problems or conflict". This means that the basic types used in an information definition must not "break" those used in the AIRM. This does allow some flexibility:

  • A basic type used in the information definition may be more restricted than that in the AIRM. For example, a real is more restricted than a Number. A string of length 4 is more restricted that a string of length 32.
  • The compatibility may be achieved by "casting" basic types. For example, an integer may be cast to a string. However, this is not always true in the reverse direction.

Assuming XML is the final output, the following mapping from ISO to XML types shall be used (based on "ISO 19118:2005 - Geographic information — Encoding") :

ISO19103:2005XML Schema Definition Language
Numberdecimal
Integerinteger
Decimaldecimal
Realdecimal
CharacterStringstring
Datedate
Timetime
DateTimedateTime
Booleanboolean

ISO standards - versions

The ISO 2005 standards referenced here are used in the AIRM and in information exchange models such as AIXM 5.1.1.

They have been updated by 2011 and 2015 versions. However, there is no fundamental change between versions on what a Boolean, etc. is. Likewise, the mapping from ISO to XML types is unaffected.

Verification Support

Consistency

Check that:

[  ] The information definition’s basic data types do not conflict with those in the AIRM.


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Status: Working Material