/// Asynchronous score request api method.
/// Most work is pushed off to an OnConnect callback.
public void RequestScoresAsync(string level, Action <ScoresResponse, ServerException> callback)
{
// Ensure arguments are valid
if (level == null)
{
throw new ArgumentNullException();
}
// external callback and argument container
RequestScoresState state = new RequestScoresState(level, callback);
// make the async connection with the onconnect callback
ConnectAsync(new AsyncCallback(RequestScoresOnConnectCallback), state);
}
/// OnConnect callback, the bulk of the work is handled here.
void RequestScoresOnConnectCallback(IAsyncResult ar)
{
RequestScoresState state = (RequestScoresState)ar.AsyncState;
// the arguments for the external callback
ServerException error = null;
ScoresResponse scores = new ScoresResponse(state.level);
// handle being unable to connect
if (!client.Connected)
{
error = new ServerException("Unable to connect");
}
else
{
try {
// form a request message and send it to the server
string request = ScoresRequest.ToJson(state.level);
WriteLine(request);
// get a response from server and convert back to an object
string response = ReadLine();
scores = ScoresResponse.FromJson(response, state.level);
} catch (ServerException e) {
error = e;
}
}
// report back to user
if (state.callback != null)
{
state.callback.Invoke(scores, error);
}
// note: even if connection failed, clean up is still necessary
DisconnectAsync(ar);
}
