Hi Eric,
Here is a solution to change service URL in accordance to selected select item:
Open "Storage and model" interface.
Add "currentRSSUrl" storage with type "string" and storage - "local storage".
Details: http://prntscr.com/6z14jp/directAdd "value change" event handler for needed select. And populate it with following JS code:
pre
//Hardcoded value for test.
var url = "http://cvunews.wordpress.com/?tag=nordic&feed=rss2";//Get url from select. Uncoment this line of code when you populated select with URL values.
//url = jQuery(this).val();localStorage.setItem("currentRSSUrl", url);
/pre
open your service.
4.1. In settings tab use "{currentURL}" in URL field.
Details: http://prntscr.com/6z15dj/direct
4.2. Navigate to request tab. Open "Query String" sub tab. And add "currentURL" parameter.
Details: http://prntscr.com/6z15q5/directOpen service datasource "before send" mapping.
Details: http://prntscr.com/6z166r/directIn datasource make link from "currentRSSUrl" storage to "currentURL" request parameter.
Details: http://prntscr.com/6z16k3/directInvoke service without any parameters(like you did above) when you need.
That's all.
Regards.