Appcelerator Cloud Service: Failed to authenticate to Node.ACS

Problem

We had to do a lot of calls from our local Node Server to the Appcelerator Cloud to get the data exported from Dev, cleaned up and uploaded to Production.  All worked fine for a while but then suddenly I started getting  a “User Not Authenticated” error.

When debugging I still found that the user is actually logged in but fails when either doing a delete, create or update to Appcelerator Cloud.  After a lot of troubleshooting I figured out that the Session Id from the Login Service was not being maintained across the different ACS calls.

Resolution

First thing is to create a global variable to store your sessionId:

var sessionId = "";

Then I create a normal login function to ACS and assign the sessionId to my variable:
The important part here is: sessionId = data.meta.session_id;

function _loginUser(req, res, options) {
    ACS.Users.login({
        login: username,
        password: password
    }, function (data) {
        if (data.success) {
//This is the important bit that needed to be added
            sessionId = data.meta.session_id;
            _StartDataImport(req, res, options);         
        } else {
            var errorMessage = ["Incorrect username and password"];
            _ReturnResult(res, 400, errorMessage);
        }
    }, req, res);
}

When performing a service call to the Appcelerator Cloud you then pass this stored variable:
The important part here is: session_id: sessionId,

function _DeleteRows(req, res) {
    ACS.Objects.remove({
        session_id: sessionId,
        classname: tableName,
        ids: itemsToDelete.join(",")
    }, function (deletedRows) {
        if (deletedRows.success) {
_ReturnResult(res, 200, ("All rows deleted!");                           
        } else {      
            _ReturnResult(res, 200, deletedRows);
        }
    }, req, res);
}

When you run your Node.ACS application now you will find that the authentication problem is no more.  I did notice in my Google ventures that other login problems also occur, but this was the one that fixed everything for me.