[Fiware-ngsi] hierarchical entities

[Juanjo Hierro]

Hi,

  We shouldn't discard the option that relationships become entities.   Why not ?    I would strongly push for that.

  I believe there are a number of advantages linked to it:

 *   Any kind of relationship could be represented that way.   Just playing with the attributes linked to "relationship" entities.
 *   We would be able to use NSGI-9 to register relationships and even to subscribe for dynamic registration of relationships.   This would be helpful in many scenarios
 *   We would use an uniform interface for everything.   Otherwise, we would need to define extensions to NGSI to deal with management of relationships.

  This was always in our vision at TID about how we could deal with relationships and the reason why we believe that many of the functions that the Configuration Management GE could expose could be exposed using the NGSI-9 interface.

  Best regards,

-- Juanjo



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On 24/03/12 22:57, Ernoe Kovacs wrote:
Denes,

I think any kind of relationship can be expressed by attributes.
So building: has an attribute hasRooms with the values room_1 and room_2.

Now, I think the point you are implicitly looking at is that containment hierarchies
can be used for special purposes, e.g. for naming. So by making the containment
relationship a special relationship, we might use this e.g. for having a hierarchical structured
resource tree following the containment relationship and having respective hierarchical names.

The “containment” relationship is special, but there might be also other and the might be
more than one “logical” containment. Person X is in his private life meber of his family
and in his business life member of his company, and in his sports life member of his sport club.

Conclusion:

-          Relationships can be expresses

-          No special relationships

We understand that some things can be done/expressed more efficient with special relationships.

-          Ernö




From: fiware-ngsi-bounces at lists.fi-ware.eu<mailto:fiware-ngsi-bounces at lists.fi-ware.eu> [mailto:fiware-ngsi-bounces at lists.fi-ware.eu] On Behalf Of Bisztray, Denes (NSN - HU/Budapest)
Sent: Samstag, 24. März 2012 13:51
To: fiware-ngsi at lists.fi-ware.eu<mailto:fiware-ngsi at lists.fi-ware.eu>
Subject: [Fiware-ngsi] hierarchical entities


Dear all,

Let me raise a problem with NGSI: it seems it does not support containment. That is, we can have entities building_1, room_1 and room_2 with their own attributes, but no relationship between them.

Is anyone aware of some solution for expressing that building_1 contains room_1 and room_2, apparently? (apart from adding metadata to bulding_1 such as childentity=room_1)



Best,

Dénes

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