[Fiware-ngsi] OMA spec interpretation egarding NGSI10 ONVALUE subscription

[Rolando Sergio (Guest)]

Hi Fermin,
I agree with Martin. Also in CQL we have always distinguished between output context attributes and trigger ones.
I agree with you that NGSI specification is very poor in giving details about this, and not only... :)

Best regards,
Sergio

________________________________
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: venerdì 21 dicembre 2012 12.57
To: Martin Bauer
Cc: fiware-ngsi at lists.fi-ware.eu
Subject: Re: [Fiware-ngsi] OMA spec interpretation egarding NGSI10 ONVALUE subscription

Dear Martin,

Thanks for the feedback!

Maybe "ambiguity" is not the right word... maybe I have said "poorness in description". In particular, in table 5.4.2.1 it would be more clearer if the text for AttributeList include something like this:

"Whenever the NotifyConditions of the subscription are meet, a notifyContext request is snet to Reference URI. This notifyContext message includes the value of this attributes for the entities in EntityIDlist"

...or a similar wording.

Best regards,

------
Fermín

El 21/12/2012 11:54, Martin Bauer escribió:
Hi Fermin,

In my opinion, the semantics you describe corresponds exactly to what was the intended
semantics in NGSI-10. The trigger attribute can, but does not have be part of the attribute list to
be returned. Where do you see the ambiguity?

Best regards,

Martin

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Dr. Martin Bauer
Senior Researcher
NEC Europe Ltd.
NEC Laboratories Europe
Software & Services Research Division
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E-Mail: Martin.Bauer at neclab.eu<mailto:Martin.Bauer at neclab.eu>
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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 Fermín Galán Márquez
Sent: Friday, December 21, 2012 11:51 AM
To: fiware-ngsi at lists.fi-ware.eu<mailto:fiware-ngsi at lists.fi-ware.eu>
Subject: [Fiware-ngsi] OMA spec interpretation egarding NGSI10 ONVALUE subscription

Hi,

Recently, I have discovered a unambiguity in the OMA spec regarding NGSI10 ONVALUE subscriptions which solution is not clear to me, so I will try to describe it in this email to know what other people involved in NGSI in the project think.

Within the subscribeContextRequest parameters you define a list of entity/attributes (marked in blue in the example below) and a attribute within the ONVALUE condition (marked in red in the example below).

<subscribeContextRequest>
  <entityIdList>
        <entityId type="Room" isPattern="false">
          <id>OfficeRoom</id>
        </entityId>
  </entityIdList>
  <attributeList>
        <attribute>temperature</attribute>
        <attribute>lightstatus</attribute>
        <attribute>pressure</attribute>
  </attributeList>
  <reference>localhost:5000/notify</reference>
  <duration>PT1H</duration>
  <notifyConditions>
        <notifyCondition>
          <type>ONCHANGE</type>
          <condValueList>
                <condValue>temperature</condValue>
          </condValueList>
        </notifyCondition>
  </notifyConditions>
  <throttling></throttling>
</subscribeContextRequest>

My interpretation is that the condValue acts as trigger but what is included in the notifyContext message are the entity/attributes included in the lists under subscribeContextRequest. So, in this case, if temperature changes, then temperature, lighstatus and pressure are notified (although lightstatus and pressure have not changed). In fact, I could even have subscriptions in which the triggering attribute is not part of the attributes being included in the notifyContext message, e.g.

  ...
  <attributeList>
        <attribute>lightstatus</attribute>
        <attribute>pressure</attribute>
  </attributeList>
  ...
          <condValueList>
                <condValue>temperature</condValue>
          </condValueList>
  ...

What do you think?

Best regards,

------
Fermín
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