Pass on a message from a channel's response transformer to another channel

[Coooz]

In a channel's Source Transformer, I put an incoming HL7 2.4 message on the channel map, to be picked up by a response transformer later on:

channelMap.put('original_msg', msg);

Now I noticed that somehow the entire message got embedded in a <HL7Message> tag. If I remove those when trying to route the message to another channel, I get a Response Transformer error:

154: globalMap.put('fhir_pat_id', fhir_pat_id);
155: //logger.info(channelMap.get('original_msg'));
156: var org_msg = channelMap.get('original_msg');
157: org_msg = org_msg.replace('<HL7Message>', '');
158: org_msg = org_msg.replace('</HL7Message>', '');
159: router.routeMessageByChannelId('25e97ebe-f9be-4855-ae2d-bbc71fd95845', org_msg); //FHIR step 2 ADT Retrieve Observations
160: if ('xml' === typeof msg) {
161:     if (msg.hasSimpleContent()) {
LINE NUMBER:	157
DETAILS:	TypeError: INVALID_CHARACTER_ERR: An invalid or illegal XML character is specified. 

However, if I leave them, I get:

ER7Serializer error
ERROR MESSAGE: Error converting XML to ER7
org.xml.sax.SAXParseException; lineNumber: 1; columnNumber: 1; Content is not allowed in prolog.
	at org.apache.xerces.util.ErrorHandlerWrapper.createSAXParseException(Unknown Source)
	at org.apache.xerces.util.ErrorHandlerWrapper.fatalError(Unknown Source)

which somehow seems worse.

Ultimately, what I need to do is route a HL7 2.4 message (stored on a channel map) from a channel's response transformer to another channel. What is the correct way to do this? I use Mirth Connect 4.4.2.

Thanks!

[pacmano1]

Firstly, you should probably stop doing globalMap.put('fhir_pat_id', fhir_pat_id);. It is not thread safe. I suspect that id is message level concept, so use $c, not $g. If you need to pass that downstream to other channels, that is what message metadata is for, or encapsulate the forwarded message in something like JSON and pull it apart in the downstream channel.

If you need to store the original HL7 message, get its raw version, not msg. Or serialize back ER7 (i.e. the pipe "text" version) the xml version you are storing.

But again, what are you really doing here in this channel?

[pacmano1]

So to be clear - You're simply receiving an HL7 message and need to supplement that message with a bit of FHIR data from a FHIR http call or two? Possibly forwarding to another channel?

[Coooz]

Yes indeed.

[Coooz]

Not "possibly" - I need to forward it to another channel.

[pacmano1]

https://github.com/pacmano1/Mirth-Snippets/blob/main/HL7%20add%20FHIR.xml

Import to 4.5 engine and looks at the response transformers for each step. Stop using $g like that, seriously. Use $c.

[pacmano1]

That example channel shows some response transformer concepts you can utilize. You could of course just make the FHIR calls and in the final response transformer do everything, because the results of destinations are available downstream as you can see from the examples. That would mean make the first FHIR call (outbound template would be set to datatype JSON and left empty) and the second destination response transformer:

tmp  =  new XML(SerializerFactory.getSerializer('HL7V2').toXML(connectorMessage.getRawData())) // this is the original HL7 Message
tmp['PID']['PID.3']['PID.3.1'] = JSON.parse($('d1').getMessage()).id // This is the response from the first destination, getting the "id" from the JSON
tmp['PID']['PID.5']['PID.5.1'] = msg['name'][0]['family'] // This is from the current response