Reply with custom ACK

Hi

The way that I have dealt with this in the past is as follows:

1) Create a DTL that accepts the incoming HL7 message as its source and  a target class of EnsLib.HL7.Message with a message structure of 2.5.1:ACK. I am using HL7 2.5.1 but it will work with any version of HL7 from HL7 2.3 upwards (probably earlier versions as well but I have not worked with versions earlier that 2.3)

2) when you invoke the Transform() method of a DTL you will notice that there are three parameters

1. pRequest (which is your source message)
2. pResponse (which is the generated target message)
3. aux

If you read the documentation, if the transform i invoked from a Business Rule then aux is an object and contains information about bthe Rule that invoked the Transform and a couple of other properties. However if you are invoking the transform from Cache ObjectScript then aux can be an instance of a class you create.

The way that I use 'aux' is as a mechanism for getting information into the DTL that is not present in either the sourc or target objects. In this example I want to send in the ACKCode and the ACKMessage.

So my DTL looks like this: (I apologise for having to paste in the class code but I have never found a way to attach classes to a Community Reply) so here goes.

My DTL Class reads as follows:

Class Example.Transformations.CreateNACKDTL Extends Ens.DataTransformDTL [ DependsOn = EnsLib.HL7.Message ]
{

Parameter IGNOREMISSINGSOURCE = 1;

Parameter REPORTERRORS = 1;

Parameter TREATEMPTYREPEATINGFIELDASNULL = 0;

XData DTL [ XMLNamespace = "http://www.intersystems.com/dtl" ]
{
<transform sourceClass='EnsLib.HL7.Message' targetClass='EnsLib.HL7.Message' sourceDocType='2.5.1:ADT_A01' targetDocType='2.5.1:ACK' create='new' language='objectscript' >
<assign value='source.{MSH:FieldSeparator}' property='target.{MSH:FieldSeparator}' action='set' />
<assign value='source.{MSH:EncodingCharacters}' property='target.{MSH:EncodingCharacters}' action='set' />
<assign value='source.{MSH:SendingApplication.NamespaceID}' property='target.{MSH:SendingApplication.NamespaceID}' action='set' />
<assign value='source.{MSH:SendingApplication.UniversalID}' property='target.{MSH:SendingApplication.UniversalID}' action='set' />
<assign value='source.{MSH:SendingApplication.UniversalIDType}' property='target.{MSH:SendingApplication.UniversalIDType}' action='set' />
<assign value='source.{MSH:SendingFacility.NamespaceID}' property='target.{MSH:SendingFacility.NamespaceID}' action='set' />
<assign value='source.{MSH:SendingFacility.UniversalID}' property='target.{MSH:SendingFacility.UniversalID}' action='set' />
<assign value='source.{MSH:SendingFacility.UniversalIDType}' property='target.{MSH:SendingFacility.UniversalIDType}' action='set' />
<assign value='source.{MSH:ReceivingApplication.NamespaceID}' property='target.{MSH:ReceivingApplication.NamespaceID}' action='set' />
<assign value='source.{MSH:ReceivingApplication.UniversalID}' property='target.{MSH:ReceivingApplication.UniversalID}' action='set' />
<assign value='source.{MSH:ReceivingApplication.UniversalIDType}' property='target.{MSH:ReceivingApplication.UniversalIDType}' action='set' />
<assign value='source.{MSH:ReceivingFacility.NamespaceID}' property='target.{MSH:ReceivingFacility.NamespaceID}' action='set' />
<assign value='source.{MSH:ReceivingFacility.UniversalID}' property='target.{MSH:ReceivingFacility.UniversalID}' action='set' />
<assign value='source.{MSH:ReceivingFacility.UniversalIDType}' property='target.{MSH:ReceivingFacility.UniversalIDType}' action='set' />
<assign value='$tr($zdt($h,3),",: ","")' property='target.{MSH:DateTimeOfMessage}' action='set' />
<assign value='source.{MSH:Security}' property='target.{MSH:Security}' action='set' />
<assign value='source.{MSH:MessageControlID}' property='target.{MSH:MessageControlID}' action='set' />
<assign value='"ACK"' property='target.{MSH:MessageType.MessageCode}' action='set' />
<assign value='source.{MSH:MessageType.TriggerEvent}' property='target.{MSH:MessageType.TriggerEvent}' action='set' />
<assign value='"ACK"' property='target.{MSH:MessageType.MessageStructure}' action='set' />
<assign value='source.{MSH:ProcessingID}' property='target.{MSH:ProcessingID}' action='set' />
<assign value='source.{MSH:VersionID}' property='target.{MSH:VersionID}' action='set' />
<assign value='source.{MSH:SequenceNumber}' property='target.{MSH:SequenceNumber}' action='set' />
<assign value='source.{MSH:ContinuationPointer}' property='target.{MSH:ContinuationPointer}' action='set' />
<assign value='source.{MSH:AcceptAcknowledgmentType}' property='target.{MSH:AcceptAcknowledgmentType}' action='set' />
<assign value='source.{MSH:ApplicationAcknowledgmentTyp}' property='target.{MSH:ApplicationAcknowledgmentTyp}' action='set' />
<assign value='source.{MSH:CountryCode}' property='target.{MSH:CountryCode}' action='set' />
<assign value='source.{MSH:PrincipalLanguageOfMessage}' property='target.{MSH:PrincipalLanguageOfMessage}' action='set' />
<assign value='source.{MSH:AltCharsetHandlingScheme}' property='target.{MSH:AltCharsetHandlingScheme}' action='set' />
<assign value='aux.ACKCode' property='target.{MSA:AcknowledgmentCode}' action='set' />
<assign value='aux.ACKMessage' property='target.{MSA:TextMessage}' action='set' />
</transform>
}

}

My AUX class definition looks like this:

Class Example.Transformations.CreateNACKDTL.AUX Extends %Persistent
{

Property ACKCode As %String;

Property ACKMessage As %String(MAXLEN = 200);

}

To generate the HL7 ACK my code reads:

classmethod GenerateACKMessage(pRequest as EnsLib.HL7.Message, byref pResponse as EnsLib.HL7.Message, pACKCode as %String(VALUELIST=",CA,CE,CR,AA,AE,AR")="AA", pACKMessage as %String(MAXLEN=500)="") as %Status

set tSC=$$$OK

try {

    set aux=##class(Example.Transformations.CreateNACKDTL.AUX).%New()

    set aux.ACKCode=pACKCode,aux.ACKMessage=pACKMessage

    set tSC=##class(Example.Transformations.CreateNACKDTL).Transform(pRequest,.pResponse,.aux) if 'tSC quit

}

catch ex {set tSC=ex.AsStatus()}

quit tSC

}

Notice that the DTL takes the SendingFaclity, SendingApplication, ReceivingFacility and ReceivingApplication and swaps them around in the DTL.

You should keep the MessageControlID the same as the incoming HL7 Message MessageControlId so that the ACK can be linked to the original HL7 request. 

The MessageTimeStamp can be updated to current Date/Time

The 'aux' mechanism is very useful. Unfortunately the documentation has one line of comment that says "if the transform is called from ObjectScript aux can contain anything you want" or words to that effect.

So I tested it in a simple example like the one above and it does indedd work and I now use it in the 30+ DTL's I amworking with at the moment.

Nigel