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Suggestion for improved references with RailML [message #214] Wed, 19 November 2008 22:18 Go to next message
Dr. Volker Knollmann is currently offline  Dr. Volker Knollmann
Messages: 17
Registered: September 2008
Junior Member
Hello newsgroup,

besides the previous question about accuracies, I received another
suggestion from the same user and I'm happy to share it with you for
discussion.

Mr. Pitz (Ansaldo) suggested the following improvement regarding linking
and references between RailML elements. Let me cite from his email:

> There seems to be no references between data in your model. XML
> allows for reference to another part of the model and we feel like
> this might be necessary to have consistent reference between
> interlocking and infrastructure model. Did you consider this kind of
> syntax (<xsd:keyref name="signal_segmentId"
> refer="segmented> <xsd:selector
> xpath="trackElements/signals/signal/location"/> <xsd:field
> xpath="segmentId"/") ?


It seems to me that this way of referencing between elements offers
additional ways of consistency checking (XML now knows that a number is
a reference and not just an arbitrary number). On the other hand,
introducing this syntax would require significant modifications in the
XSD-file although the RailML-XML-file would syntactically not be
affected. It's a change "behind the scenes".


Please give me your feedback: what do you think about introducing this
syntax in RailML?

Best regards,
Volker Knollmann

--
Dr. Volker Knollmann
RailML Infrastructure Coordinator
EMail: coord(at)infrastructurerailmlorg


Business contact:

Siemens AG
Industry Sector
I MO RA SPP SM21
Ackerstr. 22
38126 Braunschweig
Tel.: +49 (531) 226-2592
mailto:volkerknollmann(at)siemenscom
Re: Suggestion for improved references with RailML [message #215 is a reply to message #214] Mon, 24 November 2008 14:53 Go to previous message
Joachim Rubröder railML is currently offline  Joachim Rubröder railML
Messages: 0
Registered: November 2019
Hi,
references like that would be very useful for the timetable schema as
well.
An example for the timetable period (in V1.1) would look like that:

<xsd:key name="timetablePeriodId">
<xsd:selector xpath="
/timetable/timetablePeriods/timetablePeriod"/>
<xsd:field xpath="@timetablePeriodID"/>
</xsd:key>
<xsd:keyref name="timetablePeriodRefId" refer="
timetablePeriodId">
<xsd:selector xpath="./timetable/train"/>
<xsd:field xpath="@timetablePeriodID"/>
</xsd:keyref>

A drawback is, that the key/keyref has to be located in an element and we
only have one. So we will have to define all our key references in the
root element "railml". But why not?

I think this would be a good feature for our release 2.0 together with the
renamings to "id" and "xyRefId".

Best regards,
Joachim Rubröder

--
Joachim Rubröder
RailML Timetable Coordinator
EMail: coord(at)timetablerailmlorg
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