/// 
/// Create an Ack message based on a received message
/// 
///
 
 received message
///  Acknowlegde code
///  Message to be created
/// Created message
public static IMessage MakeACK(IMessage inboundMessage, string ackCode, IMessage ackMessage)
{
 Terser t = new Terser(inboundMessage);
 ISegment inboundHeader = null;
 try
 {
 inboundHeader = t.getSegment("MSH");
 }
 catch (NHapi.Base.HL7Exception)
 {
 throw new NHapi.Base.HL7Exception("Need an MSH segment to create a response ACK");
 }
 return MakeACK(inboundHeader, ackCode, ackMessage);
}

/// 
/// Create an Ack message based on a received message
/// 
/// received message
/// Acknowlegde code
/// Message to be created
/// Created message
public static IMessage MakeACK(ISegment inboundHeader, string ackCode, IMessage ackMessage)
{
 if (!inboundHeader.GetStructureName().Equals("MSH"))
 throw new NHapi.Base.HL7Exception(
 "Need an MSH segment to create a response ACK (got " + inboundHeader.GetStructureName() + ")");

 // Find the HL7 version of the inbound message:
 string version = null;
 try
 {
 version = Terser.Get(inboundHeader, 12, 0, 1, 1);
 }
 catch (NHapi.Base.HL7Exception)
 {
 // I'm not happy to proceed if we can't identify the inbound
 // message version.
 throw new NHapi.Base.HL7Exception("Failed to get valid HL7 version from inbound MSH-12-1");
 }

 // Create a Terser instance for the outbound message (the ACK).
 Terser terser = new Terser(ackMessage);

 // Populate outbound MSH fields using data from inbound message
 ISegment outHeader = (ISegment)terser.getSegment("MSH");
 DeepCopy.copy(inboundHeader, outHeader);

 // Now set the message type, HL7 version number, acknowledgement code
 // and message control ID fields:
 string sendingApp = terser.Get("/MSH-3");
 string sendingEnv = terser.Get("/MSH-4");
 terser.Set("/MSH-3", CommunicationNameOfThisApplication);
 terser.Set("/MSH-4", EnvironmentIdentifierOfThisApplication);
 terser.Set("/MSH-5", SendingApp);
 terser.Set("/MSH-6", sendingEnv);
 terser.Set("/MSH-7", DateTime.Now.ToString("yyyyMMddmmhh"));
 terser.Set("/MSH-9", "ACK");
 terser.Set("/MSH-12", version);
 // The ackCode should be "AA" if the message was correctly handled and "AE" if there was an error
 terser.Set("/MSA-1", ackCode == null ? "AA" : ackCode);
 terser.Set("/MSA-2", Terser.Get(inboundHeader, 10, 0, 1, 1));

 return ackMessage;
}