Parsing a Message |
To parse a message, ParseMessage should be invoked. If it successfully recognizes and parses a message, it will invoke one of the OnMessage events. If a parsing error occurs, the OnParseError event will be invoked by the engine if you created this event. If not, the parsing error will simply be logged.
var MessageData : string; begin MessageData := 'MSH|^~\&|REGADT|MCM|RSP1P8|MCM|199601051530|SEC|ADT^A44|00000007|P|2.5' + Chr(13); MessageData := MessageData + 'EVN|A44|199601051530' + Chr(13); MessageData := MessageData + 'PID|||MR2^^^XYZ||JONES^WILLIAM^A^JR||19501010|M|||123 EAST STREET^^NY^NY^10021||(212)111-3333|||S||ACCT1' + Chr(13); MessageData := MessageData + 'MRG|MR1^^^XYZ||ACCT1' + Chr(13); hl7Engine.ParseMessage(MessageData, 0); end; |
This list gives the order of execution which Chameleon uses to parse messages.
- An object invokes the ParseMessage method on the custom Engine component.
- This object invokes the parent's ParseMessage method.
- This method may invoke the OnMessage event which can be useful for logging the message before it is parsed.
- Control is then returned to the generated Engine object.
- The control creates an empty table object and invokes the core engine DLL to parse the message.
- If a parsing error is found, the HandleException method is invoked on the
TCHMcustomEngine object. - This function will invoke the OnParseError event if it is assigned, otherwise it will simply log the error message.
- If the parsing operation was successful, the empty table is cast to the appropriate custom message object and the message event is called for that message.
- The user's application code should handle the message and send a generated ACK after parsing the message.
The following code fragment gives a idea of what a typical message event would look like:
procedure TServerForm.hl7EngineMsgPatientAdmit(Sender: TObject;
Msg: THL7msgPatientAdmit; TransportIndex: Integer);
var
RowIndex : Integer;
begin
// The Msg.Dump function is an extremely useful method for
// viewing the content of the tables of a message. This method
// returns a string containing a formatted report of the contents
// of the message.
hl7Engine.WriteToLog(Msg.Dump);
hl7Engine.WriteToLog('Received a PatientAdmit message.');
hl7Engine.WriteToLog('PatientID:' + Msg.Patient[0].PatientID);
hl7Engine.WriteToLog('PatientMedRecord:' + Msg.Patient[0].PatientMedRecord);
hl7Engine.WriteToLog('LastName:' + Msg.Patient[0].LastName);
hl7Engine.WriteToLog('FirstName:' + Msg.Patient[0].FirstName);
hl7Engine.WriteToLog('MiddleName:' + Msg.Patient[0].MiddleName);
hl7Engine.WriteToLog('SSN:' + Msg.Patient[0].SSN);
hl7Engine.WriteToLog('DOB:' + DateToStr(Msg.Patient[0].DOB.DateTime));
hl7Engine.WriteToLog('Sex:' + Msg.Patient[0].Sex);
hl7Engine.WriteToLog('StreetAddress1:' + Msg.Patient[0].StreetAddress1);
hl7Engine.WriteToLog('StreetAddress2:' + Msg.Patient[0].StreetAddress2);
hl7Engine.WriteToLog('City:' + Msg.Patient[0].City);
hl7Engine.WriteToLog('State:' + Msg.Patient[0].State);
hl7Engine.WriteToLog('Zip:' + Msg.Patient[0].Zip);
end;
|
 | ||
|
It's not guaranteed that a table will have any rows of data. In fact, they will often not. i.e. a table is mapped to an optional segment which is not present. In this case, your code should check the CountOfRow property of each table before accessing even the first row. | ||
 |