Thanks for the response Julius.  I have used that before when the property came in the JSON consistently in the same format.  In this case it can come in as: 

"members": null,

or as:

"members": [
                {
                    "dob": "1905-05-01",
                    "firstName": "BOB",
                    "middleName": "T",
                    "nameSuffix": "",
                    "genderCode": "M",
                    "lastName": "COLLINS",
                    "memberId": "123421741",
                    "relationship": "Subscriber"
                }
            ],

Not sure this way will accommodate the two possible structures.

I am still getting "ERROR #9406: Unexpected format for value of field, members, using class base mapping".

Is there anything else that needs to be set along with the %DynamicArray?  I also tried %DynamicObject as well.

Property members As %DynamicArray; Property relationship As %String; Storage Default
{
<Data name="members">
<Attribute>members</Attribute>
<Structure>node</Structure>
<Subscript>"members"</Subscript>
</Data>

Thanks for all your help! Our group is transitioning to Iris from Mirth and Object script is a very different beast.

The [ ] seems to let it compile.  How do I access the array?  For example how would I get  physicianFirstName from the array? Before I have been able to do something like this.   Set pLOB = pResponse.memberPolicies.GetAt(1).insuranceInfo.lineOfBusiness

I now keep getting this

It was on another line below.  The error is still there but it looks like all brackets are matched.

/// REST EISL Provider API Business Operation
Class CDSM.ProviderAPI.EISLProviderAPIOperation Extends EnsLib.REST.Operation [ Language = objectscript ]
{ Parameter INVOCATION = "Queue"; Method getProviderInfo(pRequest As CDSM.ProviderAPI.Request, Output pResponse As CDSM.ProviderAPI.ProviderInfo) As %Status
{ Try { Set tSC = $$$OK
//Build the API request
Set tHttpRequest = ##class(%Net.HttpRequest).%New()
Set tHttpRequest.ContentType = "application/json"
Set tSC = pRequest.%JSONExportToStream(.tJSONRequest) Quit:$$$ISERR(tSC)
Set tSC = tHttpRequest.EntityBody.CopyFrom(tJSONRequest) Quit:$$$ISERR(tSC)
Set tSC = tHttpRequest.EntityBody.Rewind() //Build the Response
#Dim tHttpResponse As %Net.HttpResponse
Set tSC = ..Adapter.SendFormDataArray(.tHttpResponse,"POST",tHttpRequest) If $$$ISERR(tSC) && $IsObject(tHttpResponse) && (tHttpResponse.Data.Size) {
Set tSC = $$$ERROR($$$EnsErrGeneral,$$$StatusDisplayString(tSC)_":"_tHttpResponse.Data.Read())
//Quit:$$$ISERR(tSC)
} If $IsObject(tHttpResponse) {
$$$LOGINFO("Response is "_tHttpResponse.Data.Read())
Set tSC = tHttpResponse.Data.Rewind() Quit:$$$ISERR(tSC)
// Copy the contents of HttpResponse into pResponse
// Navigate pResponse and grab the things we want to store into SQL
// SQL Insert
Set pResponse=##class(CDSM.ProviderAPI.Response).%New()
Set tSC = pResponse.%JSONImport({}.%FromJSON(tHttpResponse.Data).%Get(0))}
} catch {
Set tSC = $$$SystemError
}
Quit tSC
} // below is not auto generated programmer must put XData MessageMap
{
<MapItems>
  <MapItem MessageType="CDSM.ProviderAPI.Request">
    <Method>getProviderInfo</Method>
  </MapItem>
</MapItems>
} }
 

This this error when I replace the old code with the new line.  It looks to me as though all are matched.  Is there a bug?

If the  [ ] brackets were stripped off would the class definition work?  if so how would I strip them on in the class?

I verified with the group sending the reply there will only be one.  I would define a class but the reply does not have a tag to be identified in the reply (example above). How would I build a class in that case or would it be easier to  Output pResponse As CDSM.ProviderAPI.ProviderInfo in the method as something else.  This would also  Set pResponse=##class(CDSM.ProviderAPI.Response).%New()  need changed I do believe as well.

How would I modify the code below to return the  response so that it  can be accessed as an array later in the code?

/// REST EISL Provider API Business Operation
Class CDSM.ProviderAPI.EISLProviderAPIOperation Extends EnsLib.REST.Operation [ Language = objectscript ]
{ Parameter INVOCATION = "Queue"; Method getProviderInfo(pRequest As CDSM.ProviderAPI.Request, Output pResponse As CDSM.ProviderAPI.ProviderInfo) As %Status
{ Try { Set tSC = $$$OK
//Build the API request
Set tHttpRequest = ##class(%Net.HttpRequest).%New()
Set tHttpRequest.ContentType = "application/json"
Set tSC = pRequest.%JSONExportToStream(.tJSONRequest) Quit:$$$ISERR(tSC)
Set tSC = tHttpRequest.EntityBody.CopyFrom(tJSONRequest) Quit:$$$ISERR(tSC)
Set tSC = tHttpRequest.EntityBody.Rewind() //Build the Response
#Dim tHttpResponse As %Net.HttpResponse
Set tSC = ..Adapter.SendFormDataArray(.tHttpResponse,"POST",tHttpRequest) If $$$ISERR(tSC) && $IsObject(tHttpResponse) && (tHttpResponse.Data.Size) {
Set tSC = $$$ERROR($$$EnsErrGeneral,$$$StatusDisplayString(tSC)_":"_tHttpResponse.Data.Read())
//Quit:$$$ISERR(tSC)
} If $IsObject(tHttpResponse) {
$$$LOGINFO("Response is "_tHttpResponse.Data.Read())
Set tSC = tHttpResponse.Data.Rewind() Quit:$$$ISERR(tSC)
// Copy the contents of HttpResponse into pResponse
// Navigate pResponse and grab the things we want to store into SQL
// SQL Insert
Set pResponse=##class(CDSM.ProviderAPI.Response).%New()
Set tSC = pResponse.%JSONImport(tHttpResponse.Data.Read()) Quit:$$$ISERR(tSC) }
} catch {
Set tSC = $$$SystemError
}
Quit tSC
} // below is not auto generated programmer must put XData MessageMap
{
<MapItems>
  <MapItem MessageType="CDSM.ProviderAPI.Request">
    <Method>getProviderInfo</Method>
  </MapItem>
</MapItems>
} }
 

It looks like my response is not a true JSON response (encapsulated in {}) but, is returned as a JSON array like the example.   is there any way to read in my response so that I can access the variables?

[ { "physicianFirstName": "STEVENSON", "physicianLastName": "HOWARD", "physicianMiddleNameInitial": "W", "physicianSpecialty": "null", "physicianNPI": "null", "physicianMPIN": "null", "physicianTaxID": "null", "physicianADRId": "null", "physicianAddressLine1": "null", "physicianCity": "null", "physicianState": "null", "physicianZip": "null", "physicianZipPlus4": "null", "physicianPhone": "null", "facilityNPI": "null", "facilityAddressLine1": "\"\"", "facilityCity": "\"\"", "facilityState": "\"\"", "facilityZip": "\"\"", "error": "Invalid NPI. Requested NPI should contain 10 numeric digits", "cdsm_Physician_Issue_ID": "null" } ]

Now that I have my cloned message being sent to my destination.  Is there a way to set the target argument in the Business Process settings so that the user can pick it vs hard coding?

set tSC = ..SendRequestSync("HL7FileOperation", newrequest)