There've been some requests to perform RPC invocations with HTTP GET,
as the response is cacheable by the browser (and if you believe the
word on the net, it's faster [1] than POST).
I've written a wrapup on how to get it done [2], the essentials in a
nutshell:
Given a service you want to make GETable:
interface GeoService{
String[] getListOfPlaces(String countryCode);
double[] getGeoCoordinatesForPlace(String placeCode);
}
On the client side, you need to provide the service proxy with a
request builder that performs GET requests:
public void getGeoCoordinates(final String placeCode, final
AsyncCallback callback){
((ServiceDefTarget)geoService).setRpcRequestBuilder(new
RpcRequestBuilder(){
@Override
protected RequestBuilder doCreate(String serviceEntryPoint) {
return new RequestBuilder(RequestBuilder.GET, "/myapp/geoservice?
placecode="+placeCode);
}
});
geoService.read(placeCode, callback);
}
On the server side, you need to create a servlet that does _not_
extend RemoteServiceServlet but uses the GWT RPC utilities directly:
public void doPost(HttpServletRequest request, HttpServletResponse
response)throws Exception{
String placeCode = request.getParameter("placecode");
Method method = geoService.getClass().getMethod("read", new
Class[]{String.class});
double[] coordinates = geoService.read(placeCode);
String sPayload = RPC.encodeResponseForSuccess(method,
coordinates);
byte[] payload;
payload = sPayload.getBytes("utf-8");
response.setHeader("Content-Disposition", "attachment");
response.setContentType("application/json;charset=utf-8");
response.setContentLength(payload.length);
ServletOutputStream stream = response.getOutputStream();
stream.write(payload);
}
[1] Yahoo Exceptional Performance Blog, Use GET for Ajax
http://developer.yahoo.com/performance/rules.html
[2] GWT RPC calls with Http GET method
http://georgovassilis.blogspot.com/2010/08/gwt-rpc-calls-with-http-get-method.html
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