code: function _doServiceCall(service, methodName, args) {
  		var serviceMethod = service[methodName];
  		var clientDeferred = new Deferred();
  		if (typeof serviceMethod !== 'function') { //$NON-NLS-0$
  			throw messages['Service method missing: '] + methodName;
  		}
  		// On success, just forward the result to the client
  		var onSuccess = function(result) {
  			clientDeferred.resolve(result);
  		};
  		
  		// On failure we might need to retry
  		var onError = function(error) {
  			// Forward other errors to client
  			clientDeferred.reject(error);
  		};
  		serviceMethod.apply(service, args).then(onSuccess, onError);
  		return clientDeferred;
  	}
docs: Performs a service call, handling authentication and retrying after auth.
  @returns {Promise}