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webapi Error on Element value Adhoc calls

Question asked by jramirez on Mar 11, 2016
Latest reply on Mar 15, 2016 by bshang

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I am writing a webapi app, I need to read a number of AF element values, when using a call to read a single AF element using this call:

GET /piwebapi/streamsets/E090oHuENZ2Uajs5xAdRTurw3yKcqgXn5RGAwNSuUn-EygUzE2MTAwXFBSQVhBSVIgQ08yXENPMiBHRU9MT0NBTElaQVRJT05cNjAwNDI2MA/value

Works perfectly, however, when using the valuesadhoc format:

GET /piwebapi/streamsets/value?webid=E090oHuENZ2Uajs5xAdRTurw3yKcqgXn5RGAwNSuUn-ygUzE2MTAwXFBSQVhBSVIgQ08yXENPMiBHRU9MT0NBTElaQVRJT05cNjAwNDI2MA

I am getting an error:

Unknown or invalid WebID format: 'E090oHuENZ2Uajs5xAdRTurw3yKcqgXn5RGAwNSuUn-EygUzE2MTAwXFBSQVhBSVIgQ08yXENPMiBHRU9MT0NBTElaQVRJT05cNjAwNDI2MA'.

Any ideas?

Jaime

bshang

Mar 11, 2016 10:07 PM

Correct Answer

Hi Jaime,

This is because AdHoc requires an attribute webId.

The non-adhoc call streamsets/{elementWebId}/value will get all attributes for that element.

The "adhoc" endpoint allows specifying attributes that do not share the same parent, and therefore, each attribute must be passed in the URL parameter as they cannot be inferred. The attribute webId will beging with an "A".

See the reply in context

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bshang

Mar 11, 2016 10:07 PM

Hi Jaime,

This is because AdHoc requires an attribute webId.

The non-adhoc call streamsets/{elementWebId}/value will get all attributes for that element.

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jramirez @ bshang on Mar 13, 2016 5:38 PM

Hi Barry:

Thanks for your answer, Then how can I read a number of elements at the same time in a single call?

Jaime

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pthivierge @ jramirez on Mar 14, 2016 12:13 PM

Hello Jaime,

Then how can I read a number of elements at the same time in a single call?

You'll need to make a search to get all attributes you need. Then you can keep this list in the cache of your application. Each time you need to query these attributes you can use their ID that are cached in your application.

So you will need at least two calls, the first to get the attributes WebId you need. The second to make your data call.

Hope this helps.

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gregor @ pthivierge on Mar 14, 2016 1:25 PM

Hello Jaime,

To complement Patrice's answer the call to PI Web API to retrieve StreamSets for multiple unrelated webID's (Attributes) is as follows:

https://<piwebapihost>/piwebapi/streamsets/value?webid=<webID1>&webid=<webID2>&webid=<webID3>

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jramirez @ gregor on Mar 15, 2016 7:53 PM

Guys:

You have been VERY helpful. The webapi documentation is VERY confusing....May I have a sample call for the GetRecordedAtTimeAdHoc, GetRecordedAtTime, GetRecorded, GetRecordedAdHoc showing hot to specify the time values?

I have been using fiddler to get values and getting all sort of weird errors.

https://sios-cs.ddns.net/piwebapi/streamsets/E0PiMt9Gu7w0WWLMvnyDXF1wPBrynwPq5RGA8Xjn0XMmUAU0lPU05FVFxHT0xEQ09SUFxDT05GS…

I need to get the value of an element and its atttibutes at a precise time and also for a time span.

THANKS IN ADVANCE FOR YOUR HELP!!!!

Jaime

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bshang

@ jramirez on Mar 15, 2016 10:14 PM

For GetRecordedAtTime, the call is

streamsets/recordedattime?webid=<webID1>&webid=<webID2>&webid=<webID3>&time=timeString

See https://techsupport.osisoft.com/Documentation/PI-Web-API/help/topics/time-strings.html for examples of timeStrings. As mentioned here, the time string can be "PI Time" or be parsed by .NET's DateTime.TryParse.

Since there are many time string formatting options, in practice, it is probably best to use a standard such as ISO 8601

ISO 8601 - Wikipedia, the free encyclopedia

Standard Date and Time Format Strings (see RoundTrip format specifier "o") 'yyyy'-'MM'-'dd'T'HH':'mm':'ss'.'fffffffK'

and to stick with UTC (ends with Z). E.g.

2016-03-13T04:50:31Z

1 person found this helpful

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6 Replies

bshang Mar 11, 2016 10:07 PM
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Correct Answer
Hi Jaime,

This is because AdHoc requires an attribute webId.

The non-adhoc call streamsets/{elementWebId}/value will get all attributes for that element.

The "adhoc" endpoint allows specifying attributes that do not share the same parent, and therefore, each attribute must be passed in the URL parameter as they cannot be inferred. The attribute webId will beging with an "A".
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- jramirez @ bshang on Mar 13, 2016 5:38 PM
  Mark Correct
  Correct Answer
  Hi Barry:
  
  Thanks for your answer, Then how can I read a number of elements at the same time in a single call?
  
  Jaime
  Like • Show 0 Likes0
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  - pthivierge @ jramirez on Mar 14, 2016 12:13 PM
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    Correct Answer
    Hello Jaime,
    
    Then how can I read a number of elements at the same time in a single call?
    You'll need to make a search to get all attributes you need. Then you can keep this list in the cache of your application. Each time you need to query these attributes you can use their ID that are cached in your application.
    So you will need at least two calls, the first to get the attributes WebId you need. The second to make your data call.
    
    Hope this helps.
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    - gregor @ pthivierge on Mar 14, 2016 1:25 PM
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      Correct Answer
      Hello Jaime,
      
      To complement Patrice's answer the call to PI Web API to retrieve StreamSets for multiple unrelated webID's (Attributes) is as follows:
      
      https://<piwebapihost>/piwebapi/streamsets/value?webid=<webID1>&webid=<webID2>&webid=<webID3>
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      - jramirez @ gregor on Mar 15, 2016 7:53 PM
        Mark Correct
        Correct Answer
        Guys:
        You have been VERY helpful. The webapi documentation is VERY confusing....May I have a sample call for the GetRecordedAtTimeAdHoc, GetRecordedAtTime, GetRecorded, GetRecordedAdHoc showing hot to specify the time values?
        
        I have been using fiddler to get values and getting all sort of weird errors.
        
        https://sios-cs.ddns.net/piwebapi/streamsets/E0PiMt9Gu7w0WWLMvnyDXF1wPBrynwPq5RGA8Xjn0XMmUAU0lPU05FVFxHT0xEQ09SUFxDT05GS…
        
        I need to get the value of an element and its atttibutes at a precise time and also for a time span.
        
        THANKS IN ADVANCE FOR YOUR HELP!!!!
        
        Jaime
        Like • Show 0 Likes0
        Actions
        bshang @ jramirez on Mar 15, 2016 10:14 PM
        Mark Correct
        Correct Answer
        For GetRecordedAtTime, the call is
        
        streamsets/recordedattime?webid=<webID1>&webid=<webID2>&webid=<webID3>&time=timeString
        
        See https://techsupport.osisoft.com/Documentation/PI-Web-API/help/topics/time-strings.html for examples of timeStrings. As mentioned here, the time string can be "PI Time" or be parsed by .NET's DateTime.TryParse.
        
        Since there are many time string formatting options, in practice, it is probably best to use a standard such as ISO 8601
        ISO 8601 - Wikipedia, the free encyclopedia
        Standard Date and Time Format Strings (see RoundTrip format specifier "o") 'yyyy'-'MM'-'dd'T'HH':'mm':'ss'.'fffffffK'
        
        and to stick with UTC (ends with Z). E.g.
        2016-03-13T04:50:31Z
        1 person found this helpful
        Like • Show 0 Likes0
        Actions

webapi Error on Element value Adhoc calls

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