Here is the initial script that extracts all 3 variables after the initial form load:
// This Script looks at the response to the Message that precedes it and Extracts
// variables specific to MOSS InfoPath applications. This is the first script which
// extracts 3 variables. EditingSessionId and SolutionId do not change after this
// initial extraction, but the CanaryValue does change after each form postback.
// Get the Message that immediately precedes this Script.
var msg = $context.currentItem.previousItem;
// Since there are multiple 'set-cookie' headers in the response, we can't parse
// headers using msg.RESPONSE_HTTP_HEADER. Instead we need to get the full response
// and parse it down.
// Get full response (headers and body)
var origText = msg.getResponse(msg.RESPONSE_TEXT);
$context.result.postMessage($context.result.LEVEL_INFO, "full response: " + origText);
// Extract CanaryValue from cookie (if needed)
// var pos = origText.indexOf("Set-Cookie: _InfoPath_CanaryValue");
// var newText = origText.substring(pos + 33);
// var pos = newText.indexOf(";");
// newText = newText.substring(0, pos);
// $context.result.postMessage($context.result.LEVEL_INFO, "InfoPath_CanaryValue_fromCookie: " + newText);
// $prop.set("MessageClip", "InfoPath_CanaryValue_fromCookie", newText);
// Find 'var g_objCurrentFormData' definition in response and put it into a variable (newText)
// This is just a string that contains the javascript 'var ...' string.
// This is step 1; It is not parse-able in this format.
var pos = origText.indexOf("var g_objCurrentFormData");
var newText = origText.substring(pos + 0);
var pos = newText.indexOf(";");
newText = newText.substring(0, pos);
$context.result.postMessage($context.result.LEVEL_INFO, "g_objCurrentFormData array: " + newText);
// The next step is to actually execute the 'var ...' javascript.
// Since the string is simply setting the contents of the var string to the
// variable g_objCurrentFormData, we can run it using the eval function.
// Running eval(newText) below will load the g_objCurrentFormData string into
// an array that the the script can navigate.
eval (newText);
// Extract editingSessionId
var editingSessionId = g_objCurrentFormData[3]
$context.result.postMessage($context.result.LEVEL_INFO, "InfoPath_editingSessionId: " + editingSessionId);
$prop.set("MessageClip", "InfoPath_editingSessionId", editingSessionId);
// extract solutionId
var solutionId_unencoded = g_objCurrentFormData[4]
$context.result.postMessage($context.result.LEVEL_INFO, "InfoPath_solutionId unencoded: " + solutionId_unencoded);
$prop.set("MessageClip", "InfoPath_solutionId_unencoded", solutionId_unencoded);
// Extract CanaryValue from Response Body
var canaryValue = g_objCurrentFormData[25]
$context.result.postMessage($context.result.LEVEL_INFO, "Canary Value from Response Body: " + canaryValue);
$prop.set("MessageClip", "InfoPath_CanaryValue_fromResponseBody", canaryValue);