// MB added 11/28/16
string GenerateNAK(string originalMessage)
{
// create a HL7Message object using the original message as the source to obtain details to reflect back in the ACK message
HL7Message tmpMsg = new HL7Message(originalMessage);
string trigger = tmpMsg.GetHL7Item("MSH-9.2")[0];
string originatingApp = tmpMsg.GetHL7Item("MSH-3")[0];
string originatingSite = tmpMsg.GetHL7Item("MSH-4")[0];
string messageID = tmpMsg.GetHL7Item("MSH-10")[0];
string processingID = "T"; //tmpMsg.GetHL7Item("MSH-11")[0];
string hl7Version = "2.3"; //tmpMsg.GetHL7Item("MSH-12")[0];
string ackTimestamp = DateTime.Now.Year.ToString() + DateTime.Now.Month.ToString() + DateTime.Now.Day.ToString() + DateTime.Now.Hour.ToString() + DateTime.Now.Minute.ToString();
StringBuilder NAKString = new StringBuilder();
NAKString.Append((char)0x0B);
NAKString.Append("MSH|^~\\&|HL7Listener|HL7Listener|" + originatingSite + "|" + originatingApp + "|" + ackTimestamp + "||ACK^" + trigger + "|" + messageID + "|" + processingID + "|" + hl7Version);
NAKString.Append((char)0x0D);
NAKString.Append("MSA|AR|" + messageID);
NAKString.Append((char)0x1C);
NAKString.Append((char)0x0D);
return(NAKString.ToString());
}
/// <summary>
/// Receive data from a client connection, look for MLLP HL7 message.
/// </summary>
/// <param name="client"></param>
private void ReceiveData(object client)
{
TcpClient tcpClient = (TcpClient)client;
NetworkStream clientStream = tcpClient.GetStream();
byte[] messageBuffer = new byte[4096];
int bytesRead;
String messageData = "";
String sHL7 = "";
int messageCount = 0;
//Console.WriteLine("looking for HL7...");
while (this.runThread)
{
bytesRead = 0;
try
{
// Wait until a client application submits a message
bytesRead = clientStream.Read(messageBuffer, 0, 4096);
}
catch (Exception e)
{
// A network error has occurred
logger.AddLog("Connection from " + tcpClient.Client.RemoteEndPoint + " has ended. " + e.Message);
break;
}
if (bytesRead == 0)
{
// The client has disconected
logger.AddLog("The client " + tcpClient.Client.RemoteEndPoint + " has disconnected");
break;
}
// Message buffer received successfully
messageData += Encoding.UTF8.GetString(messageBuffer, 0, bytesRead);
// Find a VT character, this is the beginning of the MLLP frame
logger.AddLog("read HL7 first line into buffer...");
int start = messageData.IndexOf((char)0x0B);
if (start >= 0)
{
logger.AddLog("found index");
// Search for the end of the MLLP frame (a FS character)
int end = messageData.IndexOf((char)0x1C);
if (end > start)
{
logger.AddLog("found end of message");
messageCount++;
try
{
// create a HL7message object from the message recieved. Use this to access elements needed to populate the ACK message and file name of the archived message
HL7Message message = new HL7Message(messageData.Substring(start + 1, end - (start + 1)));
// get the HL7 message as a text string that can be processed with nHAPI (Mike B)
sHL7 = messageData.Substring(start + 1, end - (start + 1));
messageType = message.GetHL7Item("MSH-9.1")[0];
SaveMessageToDatabase(sHL7);
if (sendNAK == false)
{ //send ACK
messageData = ""; // reset the message data string for the next message
string messageTrigger = message.GetMessageTrigger();
string messageControlID = message.GetHL7Item("MSH-10")[0];
string acceptAckType = "AL"; //message.GetHL7Item("MSH-15")[0];
string dateStamp = DateTime.Now.Year.ToString() + DateTime.Now.Month.ToString() + DateTime.Now.Day.ToString() + DateTime.Now.Hour.ToString() + DateTime.Now.Minute.ToString();
// send ACK message is MSH-15 is set to AL and ACKs not disbaled by -NOACK command line switch
if ((this.sendACK) && (acceptAckType.ToUpper() == "AL"))
{
logger.AddLog("Sending ACK (Message Control ID: " + messageControlID + ")");
// generate ACK Message and send in response to the message received
string response = GenerateACK(message.ToString()); // TO DO: send ACKS if set in message header, or specified on command line
logger.AddLog("ACK = " + response);
byte[] encodedResponse = Encoding.UTF8.GetBytes(response);
// Send response
try
{
//MB this is where you could also send a NAK
clientStream.Write(encodedResponse, 0, encodedResponse.Length);
clientStream.Flush();
}
catch (Exception e)
{
// A network error has occurred
logger.AddError("An error has occurred while sending an ACK to the client " + tcpClient.Client.RemoteEndPoint);
logger.AddError(e.Message);
break;
}
}
}
else //send NAK
{
messageData = ""; // reset the message data string for the next message
string messageTrigger = message.GetMessageTrigger();
string messageControlID = message.GetHL7Item("MSH-10")[0];
string acceptAckType = "AL"; //message.GetHL7Item("MSH-15")[0];
string dateStamp = DateTime.Now.Year.ToString() + DateTime.Now.Month.ToString() + DateTime.Now.Day.ToString() + DateTime.Now.Hour.ToString() + DateTime.Now.Minute.ToString();
// send ACK message is MSH-15 is set to AL and ACKs not disbaled by -NOACK command line switch
if ((this.sendACK) && (acceptAckType.ToUpper() == "AL"))
{
//LogInformation("Sending NAK (Message Control ID: " + messageControlID + ")");
// generate ACK Message and send in response to the message received
string response = GenerateNAK(message.ToString()); // TO DO: send ACKS if set in message header, or specified on command line
logger.AddLog("ACK = " + response);
byte[] encodedResponse = Encoding.UTF8.GetBytes(response);
// Send response
try
{
//MB this is where you could also send a NAK
clientStream.Write(encodedResponse, 0, encodedResponse.Length);
clientStream.Flush();
}
catch (Exception e)
{
// A network error has occurred
logger.AddError("An error has occurred while sending an NAK to the client " + tcpClient.Client.RemoteEndPoint);
logger.AddError(e.Message);
break;
}
}
//MB To do: Disconnect Listener after NAK
this.RequestStop();
}
}
// if false NAK
catch (Exception e)
{
messageData = ""; // reset the message data string for the next message
logger.AddError("An exception occurred while parsing the HL7 message");
logger.AddError(e.Message);
break;
}
}
}
}
//LogInformation("Total messages received:" + messageCount);
clientStream.Close();
clientStream.Dispose();
tcpClient.Close();
}
