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OnMessage Event

This is a very useful event. It allows you to intercept each message before Chameleon attempts to parse it. This is useful for:

  • Logging each incoming message before parsing it.
  • Sending a generated ACK message.

The following code fragment shows an example of how you might use this event: 

procedure TServerForm.sckServerMessage(Sender: TObject;
  Client: TCHMhl7ClientSocket; Message: String);
  var
     ACK : String;
begin
   hl7Engine.WriteToLog('Received an HL7 message');
   // We use the CHMconvertLineFeeds function to 'pretty print'
   // the HL7 message into a format that can be easily read in
   // the log files.
   hl7Engine.WriteToLog(CHMconvertLineFeeds(Message));

   hl7Engine.ParseMessage(Message, 0);

   // Send an ACK or NACK back to the client after parsing the message
   try
      try
         // Generate an ACK using the auto-acknowledgement engine
         ACK := ackEngine.GenerateAck(Message);
      except
         on TCHMexception do
         begin
            // The ACK generation failed, so we send back a hard coded NACK
            ACK := 'MSH|^~\\&|ACME|ACME_APP|XYZ|XYZ_APP|||NACK|XXX|P|2.4|\rMSA|AA|XXX|\r';
         end;
      end;
   finally
      Client.SendMessage(ACK);
   end;
end;

OnMessage Event

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