ObixPointDeviceExt (default name Points) is the container for Obix proxy points under an ObixClient. It operates as in other drivers; see “About the Points extension” in the Drivers Guide. This component creates and manages a single watch used for all points that are currently read subscribed.
The following slots are unique or have special importance:
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Watch Interval
How often the client should poll the point watch for changes. See Watch operation summary.
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Force Update
This action calls forceUpdate on all ObixProxyExts in this subtree.
The default and primary view for the Points extension is the ObixPointManager. Note that a different Points extension is used under an R2ObixClient device, the R2PointDeviceExt. It has a few additional properties related to the discovery of R2 objects.
Note that a watch is not really “COV.” The basic mechanics of a watch are as follows:
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The client requests a watch (object) to be created on the server.
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The client registers (and unregisters) objects included in the server’s watch, using hrefs. The standard subscription mechanism is used on the NiagaraAX client side to select/deselect objects.
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The client periodically polls the watch on the server at the defined Watch Interval (above).
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The server returns a list of any changes in the watched items (since the last poll).