HTTP requests from JavaScript

[elavy-harris]

I've got configuration data stored on a FHIR server, and I'd like to pull that into Mirth to use in my transformer, but I can't figure out how to do it. The fetch() method and XMLHttpRequest class don't seem to be supported in the Mirth Javascript environment.

The call I'd like to make is a GET to https://fhirserver/ConceptMap. (I probably could use HTTP instead of HTTPS, if necessary.) I'd like to execute this during the channel deploy so that the information is available when the messages start flowing.

I'm using the free version of Mirth 4.0.0.

Any suggestions?

[pacmano1]

If you want a transformer to make a http call you have to do that in java. There are examples in the forums for that.

As an alternative, and if the config data is persistent and might be used by more than one channel, you might consider using a single channel to source that configuration data and store it in a global map as an object.

The source tab can just be a JS reader that "returns true". In your destination, call the FHIR endpoint and in the response transformer assign the values needed to a $g object. Then reference that object as needed anywhere in any channel.

[elavy-harris]

Thank you. In trying the 'separate channel' approach, I found making the source a Channel Reader to be preferable, so that I could trigger it on-demand.

I didn't have success finding the examples on the forum, but a coworker gave me some code to work with (below, for reference):

	const get = new org.apache.commons.httpclient.methods.GetMethod(url);
	const client = new org.apache.commons.httpclient.HttpClient();

	get.setRequestHeader("Content-type", "application/fhir+json");

	const status = client.executeMethod(get);
	logger.info("Status=" + status);
	if (status != 200) {
		throw "Unexpected status retrieving ConceptMap: " + status;
	}

	const br = new java.io.BufferedReader(new java.io.InputStreamReader(get.getResponseBodyAsStream()));
	var resp = "";
	var line;
	while ((line = br.readLine()) != null) {
		resp = resp + line;
	}
	get.releaseConnection();

[StefanScholte]

Thank you so much for posting this piece of code.