<s:HTTPService id="weatherService"
                   url="{BASE_URL}"
                   resultFormat="object"
                   result="weatherService_resultHandler(event)"
                   fault="weatherService_faultHandler(event)"
                   showBusyCursor="true">
        <s:request xmlns="">
            <q>{cityName.text.toString()}</q>
            <format>{FORMAT}</format>
            <num_of_days>{NUMBER_OF_DAYS}</num_of_days>
            <key>{API_KEY}</key>
        </s:request>
    </s:HTTPService>

import mx.rpc.http.HTTPService;

        private function callService():void
        {
            var requestObj:Object = {};
            requestObj.q = cityName.text.toString();
            requestObj.format = FORMAT;
            requestObj.num_of_days = cNUMBER_OF_DAYS;
            requestObj.key = API_KEY;

            var weatherService:HTTPService = new HTTPService();
            weatherService.url = BASE_URL;
            weatherService.resultFormat = "object";
            weatherService.showBusyCursor = true;
            weatherService.request = requestObj;
            weatherService.addEventListener(ResultEvent.RESULT , weatherService_resultHandler);
            weatherService.addEventListener(FaultEvent.FAULT, weatherService_faultHandler);
            weatherService.send();
        }

        protected function weatherService_resultHandler(event:ResultEvent):void
        {
            trace("got result");
        }

        protected function weatherService_faultHandler(event:FaultEvent):void
        {
            trace("got fault");
        }