[Fiware-ngsi] DiscoveryAvailabilityContext interpretation in OMA NGSI spec

[Tobias Jacobs]

Hi Fermin,

We have exactly the same view on this, but we think that a more precise definition is needed of what it means when "an Entity in the EntityIdList is present".
Our suggestion is to say that an EntityId E matches a requested EntityId R, if both of the following conditions are satisfied:


1)      R is a pattern and the ID of E matches the pattern, or R is no pattern and the ID or E equals the ID of R

2)      The type of R is unspecified, or the type of E is unspecified, or both are specified and compatible. What compatible exactly means depends on the type ontology that is used; this is out of NGSI scope.

Best regards
Tobias, Martin, Salvatore


From: fiware-ngsi-bounces at lists.fi-ware.eu [mailto:fiware-ngsi-bounces at lists.fi-ware.eu] On Behalf Of Fermín Galán Márquez
Sent: Donnerstag, 14. Februar 2013 17:00
To: fiware-ngsi at lists.fi-ware.eu
Subject: [Fiware-ngsi] DiscoveryAvailabilityContext interpretation in OMA NGSI spec

Hi,

I have found another case of poorly documented operation in the OMA NGSI specification, that I would like to expose to the list members to know what do you think.

In particular, the description of discoverContextAvailability operation in section 5.3.2 defines the abstract format of the discovery in terms of ane EntityId list and a AttributeList, but not how that discovery has to be processed to produce the result. Our interpretation is as follows:

  *   If AttributeList is omitted, the discover operation returns all the context registration elements in which at least one of the entities in EntityId list is present. Each returned context registration contains all the entities original registered in the given context registration except the ones not included in the EntityId list of the discovery operation and all the attributes in the original registration.
  *   If AttributeList is not omitted, the discover operation returns all the context registration elements in which at least one of the entities in EntityId list is present and at least one of the attributes in AttributesList is present. Each returned context registration contains all the entities original registered in the given context registration except the ones not included in the EntityId list of the discovery operation and all the attributes in the original registration except the ones not incluced in AttributesList.

Let me show this with an example. Let's consider that two registrations have be done with the following information:

[cid:image001.png at 01CE0DBB.25CFE4B0]
Then the following discoveries (first and second column) will produce the following results (third and fourth column):
[cid:image002.png at 01CE0DBB.25CFE4B0]

What do you think?

Thanks!

Best regards,

------
Fermín
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