#1011 haxall history - hisRead

fabio antoci Wed 14 Sep 2022

hi all,

I would like to know if someone has experience with haxall history. In the documentation seems to be possible to read a history of a point with the function hisRead() but if i try to use it the error is throw.

Also in the documentation seems that in haxall the history of a point is saved only in the RAM so when a haxall server is restarted whole the data are lose. But in the documentation seems also that the history is stored : "This tag configures how long to buffer collected history items in memory before flushing them to the historian" https://haxall.io/doc/lib-phIoT/his-point

I would like to ask if someone knows:

  • how the historian actually works?
  • if is possible to read the history of a point?
  • if with haystack connectors the sync history works or not? (with a SkySpark main server connected to a haxall server)


Brian Frank Wed 14 Sep 2022

The Haxall historian is just a RAM based circular buffer. You have a lot of options to collect data locally using hisCollectInterval and hisCollectCov, etc. Then it is buffered until you can push/poll it to north bound applications (you can poll data using the hisRead HTTP operation). If the north bound application is SkySpark then you can use clustering + cloning to sync the data too (although please direct further SkySpark specific questions to skyfoundry forum).

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