Class Roo.data.ScriptTagProxy

Note that if you are retrieving data from a page that is in a domain that is NOT the same as the originating domain
of the running page, you must use this class, rather than DataProxy.

The content passed back from a server resource requested by a ScriptTagProxy is executable JavaScript
source code that is used as the source inside a <script> tag.

In order for the browser to process the returned data, the server must wrap the data object
with a call to a callback function, the name of which is passed as a parameter by the ScriptTagProxy.
Below is a Java example for a servlet which returns data for either a ScriptTagProxy, or an HttpProxy
depending on whether the callback name was passed:

boolean scriptTag = false;
String cb = request.getParameter("callback");
if (cb != null) {
    scriptTag = true;
    response.setContentType("text/javascript");
} else {
    response.setContentType("application/x-json");
}
Writer out = response.getWriter();
if (scriptTag) {
    out.write(cb + "(");
}
out.print(dataBlock.toJsonString());
if (scriptTag) {
    out.write(");");
}