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Aggregation-Server Specification
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jheins@hilscher.com
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12/11/2018 - 02:24
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Hello,

i'm currently working on an Aggregation-Server. I want to aggregate serveral servers of the same type, so i have n-times the same namespaces to aggregate. Is there any specification, how to aggregate serveral identic namespaces? I saw the concept of putting the serveruri as a prefix to the namespace-uri. Is that a valid approach or do i get any conflicts relating to companion specifications.

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Randy Armstrong
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12/11/2018 - 08:40
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application-uri+namespace-uri is unique if the application-uri are properly assigned by the admins.

a generic aggregator has to deal with misconfigured servers. 

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jheins@hilscher.com
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12/13/2018 - 00:30
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Yes the application-uri is unique. But when i aggregate two identical servers, i have two sets of the same namespace array.

Is it conform to change the original namepace-uri to application-uri+namespace-uri?

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Randy Armstrong
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12/14/2018 - 09:48
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You need to determine whether the namespace is a static 'type model' or a dynamic 'instance model'.

If it is a static model you cannot change the URI and you have merge the namespaces from multiple servers (usually not an issue because the type model is from a third party NodeSet such as DI).

If it is an instance model you can change the URI.

The NamespaceMetadataType tells you whether a namespace is static if it has static node ids defined.

Note that the NamespaceMetadataType allows a namespace to be both an instance model and a type model. You will need to keep the URI for the NodeIds in the static range and create new URIs for NodeIds outside the static range. However, in many cases you will never see nodes outside of the static range so you should not incur overhead assuming they might appear (i.e. the dynamic URI does not get added unless a NodeId outside the static range was encountered).

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