[Backlogmanager] [FIWARE-JIRA] (HELP-13344) [fiware-stackoverflow] How to create advanced subscriptions expression at Orion Context Broker NGSIv2?

[Fernando Lopez (JIRA)]

     [ https://jira.fiware.org/browse/HELP-13344?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Fernando Lopez reassigned HELP-13344:
-------------------------------------

    Assignee: Fermín Galán

> [fiware-stackoverflow] How to create advanced subscriptions expression at Orion Context Broker NGSIv2?
> ------------------------------------------------------------------------------------------------------
>
>                 Key: HELP-13344
>                 URL: https://jira.fiware.org/browse/HELP-13344
>             Project: Help-Desk
>          Issue Type: Monitor
>          Components: FIWARE-TECH-HELP
>            Reporter: Backlog Manager
>            Assignee: Fermín Galán
>              Labels: fiware, fiware-orion
>
> Created question in FIWARE Q/A platform on 03-08-2017 at 19:08
> {color: red}Please, ANSWER this question AT{color} https://stackoverflow.com/questions/45490529/how-to-create-advanced-subscriptions-expression-at-orion-context-broker-ngsiv2
> +Question:+
> How to create advanced subscriptions expression at Orion Context Broker NGSIv2?
> +Description:+
> According to official documentation of Orion Context Broker NGSIv2 :
>   You can include filtering expressions in conditions. For example, to
>   get notified not only if pressure changes, but if it changes within
>   the range 700-800. This is an advanced topic, see the "Subscriptions"
>   section in the NGSIv2 specification.
> At NGSIv2 subscriptions there is no notifyConditions such as NGSIv1 , it was replaced by subject.condition object:
>   condition: Condition to trigger notifications. This field is optional
>   and it may contain two properties, both optional:
>   
>   
>   attrs: array of attribute names
>   expression: an expression composed of q, mq, georel,
>   geometry and coords (see "List entities" operation above about this
>   field)
>   
> When we use subject.condition.attrs, it contains an array of attributes names,  these names define the "triggering attributes", i.e. attributes that upon creation/change due to entity creation or update trigger the notification. 
> But, for subject.condition.expression there is not example at official documentations. 
> Getting pieces of puzzle is possible to deduce :
> Is possible do combine subject.condition.expression and subject.condition.attrs. If I set and attribute different of expression,eg. attr foo with expression 'boo>10' what it will do ? Will this behave like an OR or AND ?
> Is possible to set multiple expressions.  Will this behave like an OR or AND ?
> It would be nice to have some examples of these more complex subscriptions combining the different ways of delimiting the entities in the subscription.
> NOTE: This question is related to Orion Version 1.7.0+



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