How to invoke a remote REST service in NiFi

Question

Is it possible to use xmlHttpRequest in NIFI processor to invoke remote rest service? In my case the ExecuteScript processor (using Javascript) can't evaluate XMLHttpRequest; is there any similar solution I can use to get response data?

var OutputStreamCallback = Java.type("org.apache.nifi.processor.io.OutputStreamCallback");
var StandardCharsets = Java.type("java.nio.charset.StandardCharsets");

Date.prototype.isValid = function () {
    return (Object.prototype.toString.call(this) === "[object Date]")
        && !isNaN(this.getTime());
};

var flowFile = session.get();

if (flowFile != null) {
    var fromDate = flowFile.getAttribute('fromDate')
    var uid = flowFile.getAttribute('uid')

    var xmlhttp = null;
    var result = null;

        xmlhttp = new XMLHttpRequest();
        if (typeof xmlhttp.overrideMimeType != 'undefined') {
            xmlhttp.overrideMimeType('application/json');

    } else if (window.ActiveXObject) {
        xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
    }
    xmlhttp.open('GET', "similar url here WorkInfo?dateFrom=?&uid=?", true);
    xmlhttp.send(dateFrom, uid);
    if (xmlhttp.status == 200) {
        result = 'WorkInfoDate'
    }
    flowFile = session.putAttribute(flowFile, 'filename', fromDate + '_' + result);

    flowFile = session.write(flowFile,
        new OutputStreamCallback(function (outputStream) {
            outputStream.write(command.getBytes(StandardCharsets.UTF_8))
        }));

    session.transfer(flowFile, REL_SUCCESS)
}

Answer 1

There is an InvokeHttp processor that can be used to invoke a REST service without writing any code:

https://nifi.apache.org/docs/nifi-docs/components/org.apache.nifi/nifi-standard-nar/1.3.0/org.apache.nifi.processors.standard.InvokeHTTP/index.html

The response from the service will be written to the contents of the flow file.