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HL7 event grouping in version 2.4 (nHapi)

HL7 event grouping in version 2.4 (nHapi)

Written by Division by Zero

Tuesday, 27 September 2011 09:30

Recently someone posted a question on an older post of mine. Since the question is one of the kind that more people will encounter, I want to highlight it.

In the nHapi HL7 versions before 2.4 the event mapping was quite clear. The header would describe the event type, for example ADT_A08 would describe a ADT A08 event. In version 2.4 Hl7 grouped events that needs the same data. In the nHapi implementation this grouping means that for some event there won't be a specific class. You won't be able to find an A08 class implementation. Let's keep working with the A08 event as an example.

In 2.4 the A08 event is a kind of subtype of the ADT_A01 event.

The header should look like this:
MSH|^~&|SomeApp||||20110215100411||ADT^A08^ADT_A01|11873630|P^T|2.4|||AL|EN

Instead of this:

MSH|^~&|SomeApp||||20110215100411||ADT^A08|11873630|P^T|2.4|||AL|EN

This way nHapi will parse the message as an ADT_A01 type object. If you have parsed is to an object you can do the following to get the 'sub-event':

string eventType = message.MSH.MessageType.TriggerEvent.Value;
 
 This will result in "A08" with the header as described above.
 
 So to parse the message do something like this (with the header as described above):
 PipeParser hl7Parser = new PipeParser();
 IMessage hl7Message = hl7Parser.Parse(message);
 if (hl7Message.Version == "2.4")
 {
 if (hl7Message.Message.GetStructureNam e() == "ADT_A01")
 {
 ADT_A01 message = (ADT_A01) hl7Message;
 // now you can determine if it's an A08 type
 if (message.MSH.MessageType.TriggerEvent.Value == "A08")
 {
 // Do something with the A08 event
 }
 }
 }

The ADT_A01 in version 2.4 contains different A?? events. For example A08, A01, A04 and A13. All these 'sub-events' use the same message structure. Of course, if you want to handle multiple types you have to rewrite the code I've posted here.

Tags:

hl7
nhapi

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