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Event Fame search using AFSearch for a template over a subset of elements

on Feb 7, 2018
Latest reply on Nov 26, 2018 by Rick Davin

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Hi Everyone,

I’m hitting a snag with searching for event frames (using AFSearch). I have a template setup for my event frame and it is used on many elements. I need to do a search where I get only the events associated with a subset of the elements.

It is easy to get all of them by using a template search, and I can get one by using a name search with a wild card (the element path is part of the event name). But I’m pulling my hair out with a good way to search for events associated with several elements. I know that I cannot use an OR operation, which would make life wonderful.

Also, note that I’m doing a search with index/paging, from most recent to oldest, so that needs to work. Doing a search for each element, one at a time, is really not a good option, as I would have to pull in a ton of events then sort, then return only x number that were requested.

I’m thinking that I pull in some events than I need using a template search, then filter out the elements that I don’t need, check to make sure I have enough events to return, if not then do another search to get more events, until I get the number of events I need. Paging will be a mess, but it seems like the only way.

Any ideas?

Thanks,

Lonnie

Rick Davin

Feb 13, 2018 4:46 PM

Correct Answer

Hi Lonnie,

One very important detail about nested queries that I left out earlier, you will need to upgrade both the AF Client and AF Server. Specifically, your AF Server must support the PISystemFeatures.QuerySearchAttribute feature. That particular enumeration indicates that your AF Server supports new search features added to AF 2.9.5:

AFAttributeSearch
AFNotificationContactTemplateSearch
Nested queries
New search tokens for EventFrame, IsInternal, Parent, PlugIn, and PlugInName.

I know in a private conversation that you are interested in the Parent filter.

See the reply in context

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Rick Davin

Feb 7, 2018 4:28 PM

Hi Lonnie,

Glad to see you back in the forums. I'm in meetings most of this week, but wanted to start a dialog with you about this topic. What version of AF SDK are you using? When you say elements, let's clarify that you mean referenced elements on an event frame, right? Are the elements based on a template as well?

In AF SDK 2.9.5 released in December 2017, there is new support for nested queries, so you can specify a template (or other filters) for a nested element query, and then a template yet again (plus other filters) on AFEventFrameSearch query.

1 person found this helpful

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Lonnie Bowling

@ Rick Davin on Feb 7, 2018 11:51 PM

Hi Rick,

Thanks for the response. I'm using 1 version back from that; 2.9.2. I'll load up 2.9.5 and check it out, that would be so nice if it works for me. Yes, by elements, I mean referenced elements, and everything is based on templates. I will post again after I look at the new SDK. Don't know how I missed that release, guess I have been hiding under a rock for too long!

Thanks,

Lonnie

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Rick Davin

@ Lonnie Bowling on Feb 9, 2018 1:48 PM

Hi Lonnie,

I don't have an example to match exactly what you want to do, but I do have an example illustrating nested tokens using the new AFAttributeSearch. I am sure you will be able to apply to your situation. Instead of searching on 2 templates (1 for EF and 1 for elements), I will be searching on 2 names (1 for attribute and 1 for element). The main thing is notice the syntax. All 3 examples do the same thing but do it differently. The first uses AFSearchToken, the second uses a plain query string, and the third uses an Interpolated string.

// Goal is to find attributes named "Feed Rate" on any elements named "Boiler*"

// Finds 1 attribute per element, using nested query tokens.
// New to AF 2.9.5: AFSearchToken.Tokens property.
public static void FindAttributeDemo21(AFElement root)
{
    // Set up the nested element search tokens
    var nestedTokens = new List<AFSearchToken>();
    nestedTokens.Add(new AFSearchToken(AFSearchFilter.Name, "Boiler*"));


    // Set up the outer attribute search tokens, which use the nested tokens
    var tokens = new List<AFSearchToken>();
    // The Element uses the nested token(s)
    tokens.Add(new AFSearchToken(AFSearchFilter.Element, AFSearchOperator.Equal, null, nestedTokens));
    // The Attribute uses a simple Name search
    // NOTE 'Feed Rate' is the attribute name, whereas '|Feed Rate' is the path (relative to the element).
    tokens.Add(new AFSearchToken(AFSearchFilter.Name, "Feed Rate"));

    using (var search = new AFAttributeSearch(root.Database, "attr demo 2.1", tokens))
    {
        search.CacheTimeout = TimeSpan.FromMinutes(10);
        foreach (var item in search.FindAttributes())
        {
            // do something
        }
    }
}

// Same as above but using nested { } in query strings.
public static void FindAttributeDemo22(AFElement root)
{
    // NOTE how element has nested { }. 
    var query = "Element:{Name:'Boiler*'} Name:'Feed Rate'";

    using (var search = new AFAttributeSearch(root.Database, "attr demo 2.2", query))
    {
        search.CacheTimeout = TimeSpan.FromMinutes(10);
        foreach (var item in search.FindAttributes())
        {
            // do something
        }
    }
}

// Same as above but using nested { } in Interpolated query strings.
public static void FindAttributeDemo23(AFElement root)
{
    string elemName = "Boiler*";
    string attrName = "Feed Rate";

    // This gives a compile error with an Interpolated string
    //var query = $"Element:{Name:'{elemName}'} Name:'{attrName}'";

    // Escape the { and } around literal braces with {{ and }} 
    var query = $"Element:{{Name:'{elemName}'}} Name:'{attrName}'";

    using (var search = new AFAttributeSearch(root.Database, "attr demo 2.3", query))
    {
        search.CacheTimeout = TimeSpan.FromMinutes(10);
        foreach (var item in search.FindAttributes())
        {
            // do something
        }
    }
}

To help round out the discussion, here are some links:

What's New AF 2017 R2 (AF SDK 2.9.5)

Search Overview - strongly suggest you BOOKMARK this link

AFSearchToken constructor with nested tokens

3 people found this helpful

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DLopez

@ Rick Davin on Nov 26, 2018 5:15 PM

Thanks, Rick! Building on top of this example, how would you modify the query string in your 2.2 example above in order to only return results where the attribute's Element is beneath a parent Element whose name matches a particular search mask? I believe that "Parent" is a search parameter, but I haven't seen many examples that reference it, and I haven't had much success in my own tests.

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Rick Davin

@ DLopez on Nov 26, 2018 6:22 PM

Hi Daniel,

Interesting question. So Parent has been an acceptable filter since AF 2.9.5 and it accepts a nested query of its own. I haven't tried this so it will be interesting to see if a nested query can have it's own nest query!

The original string above is: string query = "Element:{Name:'Boiler*'} Name:'Feed Rate'";

Let's say you are interested in boilers under a Parent element named "Unit 01". Offhand the first thing I would try is:

string query = "Element:{ Name:'Boiler*' Parent:{Name:'Unit 01'} } Name:'Feed Rate'";

But I need to go test that to see if it works. I'll get back to you.

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Rick Davin

@ Rick Davin on Nov 26, 2018 6:39 PM

Hey Dan,

Bad news. Looks like a nested query cannot contain its own nested query. So the syntax above would not work. Keep in mind the example there was to perform an AFAttributeSearch, which requires a nested element (or event frame) query. If you were performing an AFElementSearch, you would be able to use the nested query for Parent.

I will check with the dev team to confirm this.

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Rick Davin

@ Rick Davin on Nov 26, 2018 7:15 PM

Hello again Dan,

I confirmed with the dev team that doubly nested queries are currently not allowed for performance reasons. If this is a feature you feel you can't live without, you are invited to create an enhancement request at User Feedback for OSIsoft Products and Services .

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Rick Davin

@ Lonnie Bowling on Feb 9, 2018 8:54 PM

It was easy to miss since it was released on December 27 during busy holiday season.

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Rick Davin

Feb 13, 2018 4:46 PM

Hi Lonnie,

AFAttributeSearch
AFNotificationContactTemplateSearch
Nested queries
New search tokens for EventFrame, IsInternal, Parent, PlugIn, and PlugInName.

I know in a private conversation that you are interested in the Parent filter.

1 person found this helpful

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Lonnie Bowling

@ Rick Davin on Feb 16, 2018 12:41 AM

Thanks for all the help Rick, once I am able to get my system updated, I'll give it a shot!

Lonnie

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Rick Davin

@ Lonnie Bowling on Feb 16, 2018 4:06 PM

Cool, Lonnie. I'd love to know the results later. You can shoot me a private message or post here. If you don't, I will HUNT YOU DOWN AT PI WORLD.

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11 Replies

Rick Davin Feb 7, 2018 4:28 PM
Mark Correct
Correct Answer
Hi Lonnie,

Glad to see you back in the forums. I'm in meetings most of this week, but wanted to start a dialog with you about this topic. What version of AF SDK are you using? When you say elements, let's clarify that you mean referenced elements on an event frame, right? Are the elements based on a template as well?

In AF SDK 2.9.5 released in December 2017, there is new support for nested queries, so you can specify a template (or other filters) for a nested element query, and then a template yet again (plus other filters) on AFEventFrameSearch query.
1 person found this helpful
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- Lonnie Bowling @ Rick Davin on Feb 7, 2018 11:51 PM
  Mark Correct
  Correct Answer
  Hi Rick,
  
  Thanks for the response. I'm using 1 version back from that; 2.9.2. I'll load up 2.9.5 and check it out, that would be so nice if it works for me. Yes, by elements, I mean referenced elements, and everything is based on templates. I will post again after I look at the new SDK. Don't know how I missed that release, guess I have been hiding under a rock for too long!
  
  Thanks,
  
  Lonnie
  Like • Show 0 Likes0
  Actions
  - Rick Davin @ Lonnie Bowling on Feb 9, 2018 1:48 PM
    Mark Correct
    Correct Answer
    Hi Lonnie,
    
    I don't have an example to match exactly what you want to do, but I do have an example illustrating nested tokens using the new AFAttributeSearch. I am sure you will be able to apply to your situation. Instead of searching on 2 templates (1 for EF and 1 for elements), I will be searching on 2 names (1 for attribute and 1 for element). The main thing is notice the syntax. All 3 examples do the same thing but do it differently. The first uses AFSearchToken, the second uses a plain query string, and the third uses an Interpolated string.
    
    // Goal is to find attributes named "Feed Rate" on any elements named "Boiler*" // Finds 1 attribute per element, using nested query tokens. // New to AF 2.9.5: AFSearchToken.Tokens property. public static void FindAttributeDemo21(AFElement root) { // Set up the nested element search tokens var nestedTokens = new List<AFSearchToken>(); nestedTokens.Add(new AFSearchToken(AFSearchFilter.Name, "Boiler*")); // Set up the outer attribute search tokens, which use the nested tokens var tokens = new List<AFSearchToken>(); // The Element uses the nested token(s) tokens.Add(new AFSearchToken(AFSearchFilter.Element, AFSearchOperator.Equal, null, nestedTokens)); // The Attribute uses a simple Name search // NOTE 'Feed Rate' is the attribute name, whereas '|Feed Rate' is the path (relative to the element). tokens.Add(new AFSearchToken(AFSearchFilter.Name, "Feed Rate")); using (var search = new AFAttributeSearch(root.Database, "attr demo 2.1", tokens)) { search.CacheTimeout = TimeSpan.FromMinutes(10); foreach (var item in search.FindAttributes()) { // do something } } } // Same as above but using nested { } in query strings. public static void FindAttributeDemo22(AFElement root) { // NOTE how element has nested { }. var query = "Element:{Name:'Boiler*'} Name:'Feed Rate'"; using (var search = new AFAttributeSearch(root.Database, "attr demo 2.2", query)) { search.CacheTimeout = TimeSpan.FromMinutes(10); foreach (var item in search.FindAttributes()) { // do something } } } // Same as above but using nested { } in Interpolated query strings. public static void FindAttributeDemo23(AFElement root) { string elemName = "Boiler*"; string attrName = "Feed Rate"; // This gives a compile error with an Interpolated string //var query = $"Element:{Name:'{elemName}'} Name:'{attrName}'"; // Escape the { and } around literal braces with {{ and }} var query = $"Element:{{Name:'{elemName}'}} Name:'{attrName}'"; using (var search = new AFAttributeSearch(root.Database, "attr demo 2.3", query)) { search.CacheTimeout = TimeSpan.FromMinutes(10); foreach (var item in search.FindAttributes()) { // do something } } }
    
    To help round out the discussion, here are some links:
    
    What's New AF 2017 R2 (AF SDK 2.9.5)
    
    Search Overview - strongly suggest you BOOKMARK this link
    
    AFSearchToken constructor with nested tokens
    3 people found this helpful
    Like • Show 0 Likes0
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    - DLopez @ Rick Davin on Nov 26, 2018 5:15 PM
      Mark Correct
      Correct Answer
      Thanks, Rick! Building on top of this example, how would you modify the query string in your 2.2 example above in order to only return results where the attribute's Element is beneath a parent Element whose name matches a particular search mask? I believe that "Parent" is a search parameter, but I haven't seen many examples that reference it, and I haven't had much success in my own tests.
      Like • Show 0 Likes0
      Actions
      - Rick Davin @ DLopez on Nov 26, 2018 6:22 PM
        Mark Correct
        Correct Answer
        Hi Daniel,
        
        Interesting question. So Parent has been an acceptable filter since AF 2.9.5 and it accepts a nested query of its own. I haven't tried this so it will be interesting to see if a nested query can have it's own nest query!
        
        The original string above is: string query = "Element:{Name:'Boiler*'} Name:'Feed Rate'";
        
        Let's say you are interested in boilers under a Parent element named "Unit 01". Offhand the first thing I would try is:
        
        string query = "Element:{ Name:'Boiler*' Parent:{Name:'Unit 01'} } Name:'Feed Rate'";
        
        But I need to go test that to see if it works. I'll get back to you.
        Like • Show 0 Likes0
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        Rick Davin @ Rick Davin on Nov 26, 2018 6:39 PM
        Mark Correct
        Correct Answer
        Hey Dan,
        
        Bad news. Looks like a nested query cannot contain its own nested query. So the syntax above would not work. Keep in mind the example there was to perform an AFAttributeSearch, which requires a nested element (or event frame) query. If you were performing an AFElementSearch, you would be able to use the nested query for Parent.
        
        I will check with the dev team to confirm this.
        Like • Show 0 Likes0
        Actions
        Rick Davin @ Rick Davin on Nov 26, 2018 7:15 PM
        Mark Correct
        Correct Answer
        Hello again Dan,
        
        I confirmed with the dev team that doubly nested queries are currently not allowed for performance reasons. If this is a feature you feel you can't live without, you are invited to create an enhancement request at User Feedback for OSIsoft Products and Services .
        Like • Show 0 Likes0
        Actions
  - Rick Davin @ Lonnie Bowling on Feb 9, 2018 8:54 PM
    Mark Correct
    Correct Answer
    It was easy to miss since it was released on December 27 during busy holiday season.
    Like • Show 0 Likes0
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Rick Davin Feb 13, 2018 4:46 PM
Unmark Correct
Correct Answer
Hi Lonnie,

One very important detail about nested queries that I left out earlier, you will need to upgrade both the AF Client and AF Server. Specifically, your AF Server must support the PISystemFeatures.QuerySearchAttribute feature. That particular enumeration indicates that your AF Server supports new search features added to AF 2.9.5:
- AFAttributeSearch
- AFNotificationContactTemplateSearch
- Nested queries
- New search tokens for EventFrame, IsInternal, Parent, PlugIn, and PlugInName.
I know in a private conversation that you are interested in the Parent filter.
1 person found this helpful
Like • Show 0 Likes0
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- Lonnie Bowling @ Rick Davin on Feb 16, 2018 12:41 AM
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  Correct Answer
  Thanks for all the help Rick, once I am able to get my system updated, I'll give it a shot!
  
  Lonnie
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  - Rick Davin @ Lonnie Bowling on Feb 16, 2018 4:06 PM
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    Correct Answer
    Cool, Lonnie. I'd love to know the results later. You can shoot me a private message or post here. If you don't, I will HUNT YOU DOWN AT PI WORLD.
    Like • Show 0 Likes0
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Event Fame search using AFSearch for a template over a subset of elements

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