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Receiving archive data change events via AFDataPipe

Question asked by rzandvliet on Dec 15, 2014
Latest reply on Dec 16, 2014 by rzandvliet

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I want to receive archive data change events via the AFDataPipe. When I look at the AFSDK reference the AFDataPipeType Reference is applicable for PIDataPipe and AfDataPipe (see below). But when creating an instance of the AFDataPipe class, I'm not able to set the AFDataPipeType. Is this a mistake in the documentation or is AFDataPipe always sending Snapshots and Archive change events.

Specifies the type of data change events generated by the PIDataPipe and AFDataPipe classes.

Namespace: OSIsoft.AF.Data
Assembly: OSIsoft.AFSDK (in OSIsoft.AFSDK.dll) Version: 4.0.0.0 (2.6.1.6238)

Members

Member name	Value	Description
Snapshot	0	The datapipe will generate snapshot or current value data change events.
Archive	1	The datapipe will generate archive data change events.
TimeSeries	2	The datapipe will generate change events for a PI time series

Remarks

The PIDataPipe and AFDataPipe classes use this enumeration to define the type of data change events that are generated.

Version Information

AFSDK

Supported in: 2.6, 2.5

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Dan Fishman

Dec 15, 2014 5:20 PM

. I know in the PIDataPipe class you specify the AFDataPipeType in the constructor. I'm not seeing this for the AFDataPipe.

My AFDataPipe I quickly pieced together is only picking up snapshot changes. My thoughts are that the AFDataPipe is only for snapshot/current value data change events. I'll see if I can get archive events through the pipe.

Regards,

Dan

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Rhys Kirk

@ Dan Fishman on Dec 15, 2014 5:45 PM

Probably because 'snapshot' and 'archive' are PI data archive concepts covered by the PIDataPipe and the AFDataPipe is reliant on the Attribute Data Reference's implementation of the Data Pipe. Perhaps as a developer we have to be specific when working with PI Points with archive data and use the PIDataPipe..?

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Roger Palmen @ Rhys Kirk on Dec 15, 2014 8:09 PM

Digging around, it indeed clearly specifies this on the PiDataPipe class:

// Create a new data pipe for snapshot events

PIDataPipe myDataPipe = new PIDataPipe(AFDataPipeType.Snapshot)

But on the AFDataPipe, the constructor is indeed more easy to understand for anyone not understanding the bizarre difference between snapshot and archive:

AFDataPipe myDataPipe = new AFDataPipe()

The latter taken from: Using data pipes with future data in PI AF SDK 2.7

So i'll give my points to Rhys for the first and correct answer!

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rzandvliet @ Dan Fishman on Dec 16, 2014 7:05 AM

Dan, Rhys and Roger,

for now I conclude that this is a "documentation bug" in the AFSDK.chm helpfile. When we want to assign for updates on archive events we have to use the pi points together with PiDataPipe and maintain the reference between the pi point and af attribute by ourself.

Regards,

Robert

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Marcos Vainer Loeff

@ rzandvliet on Dec 16, 2014 11:04 AM

Hi Robert,

Yes, the documentation needs to be fixed. I will foward this issue to the developers. From my understanding, the idea of not using the AFDataPipeType is due to the fact that AFDataPipes will monitor the snapshots and historical events automatically. Nevertheless, according to my quick tests, this will only occur on PI AF SDK 2.7. On PI AF SDK 2.6, it monitors only snapshot events. You can download the PI AF SDK 2.7 Beta and compare the results.

One last thing, I recommend you to use AFDataPipe instead of PIDataPipe. The development team is adding some cool features only on the AFDataPipe class so in order to avoid having to update your code in the future, just use AFDataPipe.

Hope it helps!

1 person found this helpful

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rzandvliet @ Marcos Vainer Loeff on Dec 16, 2014 12:18 PM

Marcos,

Thanks for updating. for snapshot we can use AFDataPipe, but we also need to retrieve archive updates. At the moment this can only be done via the PiDataPipe, because of installed PI Server and AF SDK versions . We will try to abstract the data retrieval layer from the rest of the application and change it when functionality becomes available and servers has been updated.

Regards,

Robert

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6 Replies

Dan Fishman Dec 15, 2014 5:20 PM
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Correct Answer
. I know in the PIDataPipe class you specify the AFDataPipeType in the constructor. I'm not seeing this for the AFDataPipe.

My AFDataPipe I quickly pieced together is only picking up snapshot changes. My thoughts are that the AFDataPipe is only for snapshot/current value data change events. I'll see if I can get archive events through the pipe.
Regards,
Dan
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- Rhys Kirk @ Dan Fishman on Dec 15, 2014 5:45 PM
  Mark Correct
  Correct Answer
  Probably because 'snapshot' and 'archive' are PI data archive concepts covered by the PIDataPipe and the AFDataPipe is reliant on the Attribute Data Reference's implementation of the Data Pipe. Perhaps as a developer we have to be specific when working with PI Points with archive data and use the PIDataPipe..?
  1 person found this helpful
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  - Roger Palmen @ Rhys Kirk on Dec 15, 2014 8:09 PM
    Mark Correct
    Correct Answer
    Digging around, it indeed clearly specifies this on the PiDataPipe class:
    // Create a new data pipe for snapshot events
    PIDataPipe myDataPipe = new PIDataPipe(AFDataPipeType.Snapshot)
    
    But on the AFDataPipe, the constructor is indeed more easy to understand for anyone not understanding the bizarre difference between snapshot and archive:
    AFDataPipe myDataPipe = new AFDataPipe()
    
    The latter taken from: Using data pipes with future data in PI AF SDK 2.7
    
    So i'll give my points to Rhys for the first and correct answer!
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- rzandvliet @ Dan Fishman on Dec 16, 2014 7:05 AM
  Mark Correct
  Correct Answer
  Dan, Rhys and Roger,
  
  for now I conclude that this is a "documentation bug" in the AFSDK.chm helpfile. When we want to assign for updates on archive events we have to use the pi points together with PiDataPipe and maintain the reference between the pi point and af attribute by ourself.
  
  Regards,
  Robert
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  - Marcos Vainer Loeff @ rzandvliet on Dec 16, 2014 11:04 AM
    Mark Correct
    Correct Answer
    Hi Robert,
    
    Yes, the documentation needs to be fixed. I will foward this issue to the developers. From my understanding, the idea of not using the AFDataPipeType is due to the fact that AFDataPipes will monitor the snapshots and historical events automatically. Nevertheless, according to my quick tests, this will only occur on PI AF SDK 2.7. On PI AF SDK 2.6, it monitors only snapshot events. You can download the PI AF SDK 2.7 Beta and compare the results.
    
    One last thing, I recommend you to use AFDataPipe instead of PIDataPipe. The development team is adding some cool features only on the AFDataPipe class so in order to avoid having to update your code in the future, just use AFDataPipe.
    
    Hope it helps!
    1 person found this helpful
    Like • Show 0 Likes0
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    - rzandvliet @ Marcos Vainer Loeff on Dec 16, 2014 12:18 PM
      Mark Correct
      Correct Answer
      Marcos,
      
      Thanks for updating. for snapshot we can use AFDataPipe, but we also need to retrieve archive updates. At the moment this can only be done via the PiDataPipe, because of installed PI Server and AF SDK versions . We will try to abstract the data retrieval layer from the rest of the application and change it when functionality becomes available and servers has been updated.
      
      Regards,
      Robert
      Like • Show 0 Likes0
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Receiving archive data change events via AFDataPipe

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