| Required 'id' attributes (was: More detailed 'speed change' definitions) [message #420 is a reply to message #322] |
Wed, 07 November 2012 14:25   |
Susanne Wunsch railML
Messages: 0
Registered: January 2020
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Hello Dirk and others,
The following aspect was quite overseen, sorry for that.
I changed the follow-up to railML.misc because of the more general
topic.
Dirk Bräuer <dirkbraeuer(at)irfpde> writes:
> <speedChange id="sc3"...>
>
> Can we have the ‚id’ of a speed change as an optional attribute? Since
> we have many, many speed changes and seldom the need to refer to them
> I do (optionally) want to save some space and effort.
* The "id" attribute provides good facilities to fetch single elements
(with its attributes and sub-elements) from an XML file irrespective
of an existing reference in the XML file.
* There are other often-used XML standards that use the same mechanism:
e.g. GML (Geographic Markup Language)
<attribute name="id" type="ID">
<annotation>
<documentation>The attribute gml:id supports provision of a handle
for the XML element representing a GML Object. Its use is
mandatory for all GML objects. It is of XML type ID, so is
constrained to be unique in the XML document within which it
occurs.</documentation>
</annotation>
</attribute>
<complexType name="AbstractGMLType" abstract="true">
<sequence>
<group ref="gml:StandardObjectProperties"/>
</sequence>
<attribute ref="gml:id" use="required"/>
</complexType>
This attribute is required for all GML objects irrespective any
reference.
A huge amount of XML Schemas in the Geographic field of application
base on the above mentioned XML Schema.
* It is already a very smart implementation for identification.
The following example shows up a typical alternative from the banking
sector:
<act:id type="guid">aa671349a0befafcfff1773e42eb8a49</act:id>
* There are algorithms for different programming languages for the
ID-generation in general.
e.g. generate-id() in XPath (staying at the XML-world) ;-)
* The _required_ attribute may only be changed into "optional" for the
next major release.
I hope it clarifies the issue a bit.
Kind regards...
Susanne
Crosspost & Followup-To: railML.misc
--
Susanne Wunsch
Schema Coordinator: railML.common
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