[Fiware-ngsi] register context problem

[Bisztray, Denes (NSN - HU/Budapest)]

Hi Tobias, all,

 

Since I don't see any other meaningful solution, I agree. 

If we go down this road, there are some other open questions:

 

-          All items (except the ProvidingApplication) in the ContextRegistrationList are optional. As I understand either the EntityIdList AND ContextRegistration or the ContextMetadata is present. What should happen when we "update the metadata of the providing application" and no EntityIds are present, as they are not necessary? How does this information relate to the ContextElements?

 

-          If we give registrationId, it means we update a previous registration. What is the exact point of it? We already have an updateContext, what is the difference of this update of registration?

 

Best,

Dénes

 

 

 

From: ext Tobias Jacobs [mailto:Tobias.Jacobs at neclab.eu] 
Sent: Tuesday, April 17, 2012 11:46 AM
To: Bisztray, Denes (NSN - HU/Budapest); fiware-ngsi at lists.fi-ware.eu
Subject: RE: register context problem

 

Hi Denes,

 

NEC strongly votes for the second possibility (all Entities with all attributes). The Metadata then holds for every single Entity/Attribute combination registered.

 

This way you could express information like "I can provide the position and the speed of car_1, car_2, and car_3 with an accuracy of +-10%" in one ContextRegistration instance.

If the metadata information has to be more fine-grained, then one has to use multiple ContextRegistration instances.

 

Best regards

Tobias

 

 

 

From: 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: Dienstag, 17. April 2012 10:40
To: fiware-ngsi at lists.fi-ware.eu
Subject: [Fiware-ngsi] register context problem

 

Dear all,

As per request I summarise my problems with the NGSI-9 registerContext. 

As one can see, the request contains a list of ContextRegistration structures which contains the following (page 25, sec 5.5.7 ):

-       List of EntityIDs (optional)

-       List of ContextRegistrationAttributes (optional) - List of ContextAttributes and/or AttributeDomains which are made available through this registration.

-       List of ContextMetadata (optional)

So the problem is the following:

How do we match the EntityId set with the contextAttribute and contextMetadata set?

Possible solutions I can come up with:

-       Match by position, i.e. EntityId[4] matches with ContextRegistrationAttributes[4]. This solution is blatantly flawed, as one Entity can have only one attribute.

-       All Entities will have all attributes. This could work, but then what do we do with the contextMetadata. How do we map them to the attributes...

So I cannot really see what the designers were thinking when they came up with this message.

Best,

Dénes

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