A couple of people have asked me about caching and Flex. Once or twice about the datagrid and a couple of times about the session object not accepting that the user was logged-in in the simple demo.

To get round this you can add an extra parameter to the HTTPService to add anti-caching to it, like so:

Each time the service requests the session.object form it adds a different ending to the URL, such as:

/apps/flex.nsf/flex/session.object?ReadForm&nocache=1234476539548

Problem solved.

Note also that you can pass the parameters to the HTTPService via (Action)Script rather than by nesting them in an <mx:request> object, with a function like this:

private function requestSessionData():void{
        var params:Object = new Object();
        params.nocache = new Date().getTime();
        httpSession.send(params);
}

Which you use is down to both personal preference and, to a degree, circumstance. With the latter method you get the choice of which parameters you do or don't want to send. Not so with the request object.