Howto: RPC with Http GET

[George Georgovassilis]

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

[mmoossen]

good hint!

thanks for sharing
Michael

On Aug 28, 11:29 am, George Georgovassilis

> [1] Yahoo Exceptional Performance Blog, Use GET for Ajaxhttp://developer.yahoo.com/performance/rules.html
>
> [2] GWT RPC calls with Http GET methodhttp://georgovassilis.blogspot.com/2010/08/gwt-rpc-calls-with-http-ge...