AF-SDK-Programming-Online-Course/Exercise4/CSharp/Limit Check DataReference/Limit Check DataReferenc

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//*********************************************************************************************************

// PIDevClub.DataReference.LimitCheck.dll

//---------------------------------------------------------------------------------------------------------

// This custom data reference will accept an input attribute, automatically find its related limit traits,

// and compare the value of the input attribute against the limits. Note that there could be 0-4 different

// limit traits { Lo, Hi, LoLo, HiHi }.

// An Int32 value is returned representing 1 of 5 possible states:

// -2 : <= LoLo

// -1 : <= Lo (but not LoLo)

// 0 : Normal, i.e. within limits

// +1 : >= Hi (but not HiHi)

// +2 : >= HiHi

// The result Attribute could be using Int32 data type, although a raw number lacks context.

// It is recommended to created an AFEnumerationSet based on the above codes with desired text.

// You may use different enumeration sets with different text, but the codes must be the same.

//---------------------------------------------------------------------------------------------------------

// HISTORY:

// Developer Date Reason

// ------------------------- ---------- -----------------------------------------------------------------

// Rick Davin 2017-09-28 Created for Exercise 4 in AF SDK online course.

//*********************************************************************************************************

using System ;

using System . Collections . Generic ;

using System . Linq ;

using System . Text ;

using System . Threading . Tasks ;

using System . Runtime . InteropServices ;

using System . ComponentModel ;

using OSIsoft . AF ;

using OSIsoft . AF . Asset ;

using OSIsoft . AF . Time ;

using OSIsoft . AF . Data ;

using OSIsoft . AF . UnitsOfMeasure ;

namespace LimitCheckDR

{

[ Guid ( " 8DA87B2A-38D9-4CF6-9BA0-C75314A6B5DC " ) ,

Serializable ( ) ,

Description ( " Limit Check;Compares a measurement to its limit traits. " ) ]

public class LimitCheckDR : AFDataReference

{

// Rather than look up and validate the limit traits each instant data is requested,

// we will keep a tiny cache of no more than 5 attributes in memory.

// You are free to adjust the cache duration, though I would recommend no more than 2 minutes

// and no less than 10 seconds. If you insist on no caching, you could disable

// the code in GetInputs or use a span of 0 seconds.

// Bonus Challenge: You could make the duration be a setting in the ConfigString.

private static TimeSpan _cacheRefreshDuration = TimeSpan . FromSeconds ( 30 ) ;

private DateTime _lastCachedTime = DateTime . UtcNow . AddDays ( - 1 ) ;

private AFAttributeList _cachedInputAttrs = new AFAttributeList ( ) ;

// The default measurement name is relative dot reference to the parent attribute.

private const string DefaultMeasPath = " .. " ;

private string _measAttrName = DefaultMeasPath ;

private bool UseParentAttribute => string . IsNullOrWhiteSpace ( _measAttrName ) || _measAttrName == DefaultMeasPath ;

private AFAttributeTrait [ ] AllowedTraits => new AFAttributeTrait [ ] { AFAttributeTrait . LimitLo

, AFAttributeTrait . LimitHi

, AFAttributeTrait . LimitLoLo

, AFAttributeTrait . LimitHiHi } ;

private class TripState

{

public const int None = 0 ;

public const int LowLow = - 2 ;

public const int Low = - 1 ;

public const int High = 1 ;

public const int HighHigh = 2 ;

}

// https://techsupport.osisoft.com/Documentation/PI-AF-SDK/html/P_OSIsoft_AF_Asset_AFDataReference_ConfigString.htm

public override string ConfigString

{

get

{

return $" MeasAttr= { _measAttrName } " ;

}

set

{

// We will always force the cache to refresh anytime we change ConfigString.

_lastCachedTime = DateTime . UtcNow . AddDays ( - 1 ) ;

// We clear out any previously set values to their defaults.

// For now, we only have 1 to worry about but that could change in future versions.

_measAttrName = DefaultMeasPath ;

// With only 1 name=value pair, we don't have a semi-colon delimiter, but the

// example shown will pretend there is one. This allows for future expansion for more name=value pairs.

var pairs = value . Split ( new char [ ] { ';' } , StringSplitOptions . RemoveEmptyEntries ) ;

foreach ( var pair in pairs )

{

// Question: what to do if tokens.Count is not 2 as expected?

var tokens = pair . Split ( new char [ ] { '=' } , StringSplitOptions . None ) ;

switch ( tokens [ 0 ] . ToUpperInvariant ( ) )

{

case " MEASATTR " :

// You will note we do very little validation on the _measAttrName.

// That should not be a concern of the ConfigString setter, whose only

// concern should be parsing the string. We defer to other methods,

// such as GetInputs, to validate if the parsed string refers to valid

// AFObjects.

if ( tokens . Length > 1 && ! string . IsNullOrEmpty ( tokens [ 1 ] ) )

{

_measAttrName = tokens [ 1 ] . Trim ( ) ;

}

break ;

default :

throw new ArgumentException ( " Invalid parameter '{tokens[0]}'. " ) ;

}

// Important to persist changes back to database via this protected method call:

SaveConfigChanges ( ) ;

}

// https://techsupport.osisoft.com/Documentation/PI-AF-SDK/html/M_OSIsoft_AF_Asset_AFDataReference_GetInputs.htm

public override AFAttributeList GetInputs ( object context )

{

// Internal time keeping is done by UTC so we completely avoid even the slightest hint of any DST issues.

if ( ( DateTime . UtcNow - _lastCachedTime ) < _cacheRefreshDuration )

{

return _cachedInputAttrs ;

}

// PRO TIP: although _cachedInputAttrs is accessible to the entire class instance, you want to avoid

// using _cachedInputAttrs.Add or AddRange in name of thread safety. The safer route is to build

// the list in its own local variable, and once that local list is completely created, you may then

// assign that local variable to _cachedInputAttrs.

// To help emphasize that, the local list is created in its own method.

_cachedInputAttrs = CreateBrandNewInputList ( context ) ;

// Since the above could throw an exception, we only want to mark _lastCachedTime AFTER a

// successful creation of the inputs.

_lastCachedTime = DateTime . UtcNow ;

return _cachedInputAttrs ;

}

private AFAttributeList CreateBrandNewInputList ( object context )

{

// PRO TIP:

// See comments in GetInputs where you want to avoid _cachedInputAttrs.Add or AddRange.

// For thread safety, use a brand new list that is local to this method.

// Start with a brand new list

var brandNewList = new AFAttributeList ( ) ;

AFAttribute measurement = null ;

// First and foremost we need a measurement attribute, which is the centerpoint to compare against limits.

if ( UseParentAttribute )

{

// https://techsupport.osisoft.com/Documentation/PI-AF-SDK/html/P_OSIsoft_AF_Asset_AFDataReference_Attribute.htm

// https://techsupport.osisoft.com/Documentation/PI-AF-SDK/html/P_OSIsoft_AF_Asset_AFAttribute_Parent.htm

measurement = Attribute . Parent ;

if ( measurement == null )

{

throw new Exception ( " Root-level attribute does not have a parent. You must define 'MeasAttr=something' in the ConfigString. " ) ;

}

else

{

// Let's offer some bit of name substitution.

// However, the GetInputs method lacks any timeContext, which restricts @value substitution

// to current values only. This restriction is fine for static attributes.

// https://techsupport.osisoft.com/Documentation/PI-AF-SDK/html/T_OSIsoft_AF_AFNameSubstitutionType.htm

var path = SubstituteParameters ( _measAttrName , this , context , timeContext : null ) ;

// Note that the final fetch of the measurement attribute is *relative* to the current Attribute.

// https://techsupport.osisoft.com/Documentation/PI-AF-SDK/html/P_OSIsoft_AF_Asset_AFAttribute_Attributes.htm

measurement = Attribute . Attributes [ path ] ;

if ( measurement == null )

{

throw new Exception ( $" MeasAttr ' { _measAttrName } ' not found. Check your ConfigString. " ) ;

}

if ( ! IsNumericType ( Type . GetTypeCode ( measurement . Type ) ) )

{

throw new Exception ( $" MeasAttr does not have a numeric Type. " ) ;

}

// If the list will have any items, the measurement will always be at Index 0.

brandNewList . Add ( measurement ) ;

// Let the CDR automatically fetch the associated limits.

// These could come back in any order, plus some or all may be missing!

// Geez, doesn't that make it fun and challenging!

// https://techsupport.osisoft.com/Documentation/PI-AF-SDK/html/M_OSIsoft_AF_Asset_AFAttribute_GetAttributesByTrait.htm

brandNewList . AddRange ( measurement . GetAttributesByTrait ( AllowedTraits ) ) ;

return brandNewList ;

}

// In order for the Step property to be accessible from other apps such PI Vision or ProcessBook,

// the CDR will need to support the ZeroAndSpan method.

public override bool Step => true ;

// Your CDR does not necessarily have to override GetValues in order to support it.

// You may use the default implementation, which does not require additional coding on your part.

// https://techsupport.osisoft.com/Documentation/PI-AF-SDK/html/P_OSIsoft_AF_Asset_AFDataReference_SupportedMethods.htm

public override AFDataReferenceMethod SupportedMethods => AFDataReferenceMethod . GetValue

| AFDataReferenceMethod . GetValues

| AFDataReferenceMethod . ZeroAndSpan ;

// For Rich Data Access support, we will merely declare what we want supported, and then rely on the base implementation.

// What that means is we don't have to write any code in order to support these methods. Nice. Very nice.

// https://techsupport.osisoft.com/Documentation/PI-AF-SDK/html/P_OSIsoft_AF_Asset_AFDataReference_SupportedDataMethods.htm

public override AFDataMethods SupportedDataMethods => DefaultSupportedDataMethods ;

// PRO TIP: the allows analytics and other clients to work more efficiently with a calcuation DR.

protected override bool ? IsSupportedDataMethod ( AFDataMethods dataMethods ) => IsDefaultSupportedDataMethod ( dataMethods ) ;

// https://techsupport.osisoft.com/Documentation/PI-AF-SDK/html/M_OSIsoft_AF_Asset_AFDataReference_GetValue_1.htm

public override AFValue GetValue ( object context , object timeContext , AFAttributeList inputAttributes , AFValues inputValues )

{

// Important to note that the order of inputValues matches the order of inputAttributes.

// Note that timeContext is an object.

// We need to examine it further in order to resolve it to an AFTime.

var time = ToAFTime ( timeContext ) ;

AFValue measurement = null ;

AFValue low = null ;

AFValue high = null ;

AFValue lowlow = null ;

AFValue highhigh = null ;

// https://techsupport.osisoft.com/Documentation/PI-AF-SDK/html/P_OSIsoft_AF_Asset_AFAttribute_Trait.htm

// https://techsupport.osisoft.com/Documentation/PI-AF-SDK/html/T_OSIsoft_AF_Asset_AFAttributeTrait.htm

for ( var i = 0 ; i < inputAttributes . Count ; i ++ )

{

if ( i == 0 )

{

measurement = inputValues [ i ] ;

}

else if ( inputAttributes [ i ] . Trait == AFAttributeTrait . LimitLo )

{

low = inputValues [ i ] ;

}

else if ( inputAttributes [ i ] . Trait == AFAttributeTrait . LimitHi )

{

high = inputValues [ i ] ;

}

else if ( inputAttributes [ i ] . Trait == AFAttributeTrait . LimitLoLo )

{

lowlow = inputValues [ i ] ;

}

else if ( inputAttributes [ i ] . Trait == AFAttributeTrait . LimitHiHi )

{

highhigh = inputValues [ i ] ;

}

// Remember any of the passed AFValues could be null if the limit trait is not defined.

// This is a fact of life and reflects the many possibilities within a given process unit.

return Calculation ( time , measurement

, low

, high

, lowlow

, highhigh ) ;

}

private AFValue Calculation ( AFTime time , AFValue measurement , AFValue low , AFValue high , AFValue lowlow , AFValue highhigh )

{

// Our custom ToDouble returns double.NaN for null, missing, bad data, or bad conversions.

var numericMeasurement = ToDouble ( measurement ) ;

if ( double . IsNaN ( numericMeasurement ) )

{

// https://techsupport.osisoft.com/Documentation/PI-AF-SDK/html/M_OSIsoft_AF_Asset_AFValue_CreateSystemStateValue.htm

return AFValue . CreateSystemStateValue ( Attribute , AFSystemStateCode . NoResult , time ) ;

}

// Remember: any or all of the limits could be null. In those bad cases, a double.NaN is sent.

var calc = Calculation ( numericMeasurement , ToDouble ( low ) , ToDouble ( high ) , ToDouble ( lowlow ) , ToDouble ( highhigh ) ) ;

return new AFValue ( Attribute , calc , time ) ;

}

private static int Calculation ( double measurement , double low , double high , double lowlow , double highhigh )

{

// If any limits were missing or bad, they will be a NaN here.

// A NaN used in comparisons will return false, which is what we want below. That is,

// a comparison will return true only if the limit is not NaN and the limit has been met.

if ( measurement >= highhigh )

{

return TripState . HighHigh ;

}

if ( measurement <= lowlow )

{

return TripState . LowLow ;

}

if ( measurement >= high )

{

return TripState . High ;

}

if ( measurement <= low )

{

return TripState . Low ;

}

return TripState . None ;

}

private AFTime ToAFTime ( object timeContext )

{

if ( timeContext is AFTime )

{

return ( AFTime ) timeContext ;

}

else if ( timeContext is AFTimeRange )

{

var baseElement = Attribute . Element ;

var useStartTime = ( baseElement is AFEventFrame ) ;

var timeRange = ( AFTimeRange ) timeContext ;

return useStartTime ? timeRange . StartTime : timeRange . EndTime ;

}

return AFTime . NowInWholeSeconds ;

}

private static bool IsNumericType ( TypeCode typeCode )

{

switch ( typeCode )

{

case TypeCode . Byte :

case TypeCode . Decimal :

case TypeCode . Double :

case TypeCode . Int16 :

case TypeCode . Int32 :

case TypeCode . Int64 :

case TypeCode . SByte :

case TypeCode . Single :

case TypeCode . UInt16 :

case TypeCode . UInt32 :

case TypeCode . UInt64 :

return true ;

default :

return false ;

}

private static double ToDouble ( AFValue value )

{

if ( value == null || ! value . IsGood || ! IsNumericType ( value . ValueTypeCode ) )

{

return double . NaN ;

}

// https://techsupport.osisoft.com/Documentation/PI-AF-SDK/html/M_OSIsoft_AF_Asset_AFValue_ValueAsDouble.htm

return value . ValueAsDouble ( ) ;

}