[railML3] netElement aggregation [message #3304] |
Wed, 04 September 2024 15:33 |
Milan Wölke
Messages: 146 Registered: April 2007
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Senior Member |
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Hi all,
while working on the extensions for railML 3.3 I noticed an oddity in the infrastructure subschema, more precisely in the RTM part of the infrastructure.
When aggregating <netElement>s you specify a new <netElement> on the aggregated layer of the infrastructure. In order to express which <netElement>s of the lower layer of the infrastructure are actually aggregated into the new <netElement> you can specify them in the child element <elementCollectionOrdered> or <elementCollectionUnordered>. Thats clear and straightforward. However, I noticed that there is the option to specify multiple such collections, so you can specify multiple <elementCollectionOrdered> elements or multiple <elementCollectionUnordered>. I followed this back to the RTM which also allows for this. From my point of view this doesnt make sense. Why would one specify multiple collections of aggregated elements? If this would be elements of different layers of that are aggregated into one I think this would better be expressed with an intermediate <netElement>.
Do you use multiple such collections when aggregating <netElement>s? How would be your understanding?
If this is not used by anyone, I would propose to reduce the multiplicity here to 1 so that the meaning becomes more clear. I would also argue that this should be then taken over into RTM version 1.5.
What do you think?
Best regards, Milan
Milan Wölke – Timetable scheme coordinator
railML.org (Registry of Associations: VR 5750)
Altplauen 19h; 01187 Dresden; Germany www.railML.org
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Re: [railML3] netElement aggregation [message #3306 is a reply to message #3304] |
Wed, 04 September 2024 16:18 |
Thomas Nygreen
Messages: 75 Registered: March 2008
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Member |
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Hi Milan,
I also wondered about this a few days ago, and could not find any previous discussion about it. It looks to me like a modelling error in RTM. The <elementCollectionOrdered> also has the @sequence number on the collection, not on the parts. Unless someone can provide a reason for this modelling, I agree with your proposal, and suggest to move @sequence from the collection to the elementPart.
Best regards,
Thomas
Thomas Nygreen – Common Schema Coordinator
railML.org (Registry of Associations: VR 5750)
Altplauen 19h; 01187 Dresden; Germany www.railML.org
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