How to Add Downstream Query Parameters

This is short and sweet. It provides a very simple script that appends a new string to the existing query string. If you want an all-new string ignoring anything inbound, that's a pretty simple code change.

var msg = processContext.getVariable("message");

// Read the existing query string
var queryString = msg.getProperty("com.soa.message.TRANSPORT_QUERY");
var newQueryString = "";

// if there is a query string
if (queryString) {
  // Append the new string to the existing one
  newQueryString = String(queryString).concat("&newParamName=newParamValue");
} else {
  // Make a new query string
  newQueryString = "newParamName=newParamValue";

// And set the new query string
msg.setProperty("com.soa.message.TRANSPORT_QUERY", newQueryString);

That's it. Nice and simple.