While building up the server side RPC methods for client side calls from ExtJS’s new Direct RPC framework, I thought it would be useful to fail fast whenever the client caller violated the interface contract. Enter fail fast.
def submit(params) action = params.delete(:action) id = params.delete(:id) assert(action) {|v| ['update', 'create'].include?(v)} ...
Further up the stack, we can handle the exception and cleanly fail the client side request. From within active-direct.
def invoke_method(model, method, parameters, tid) ... unless parameters.nil? return_val = model.constantize.send(method, *normalize_params_for(model,parameters)) else return_val = model.constantize.send(method) end result['result'] = return_val.nil? ? "" : return_val # Must catch descendant of Exception explicitly rescue FailFast::AssertionFailureError => e Rails.logger.error result['type'] = 'exception' Rails.logger.error result['message'] = e.message Rails.logger.error result['where'] = e.backtrace.join("\n") ... ensure return result end
The entry point to a RPC is a good place to ensure contract validity.
