17.1DIFF协议
DIFF(Differential Information Flow for Finance)是一个基于websocket和json的应用层协议。websocket是全双工通信，当客户端和服务器端建立连接后，就可以相互发数据，建立连接又称为“握手”，“握手”成功就可以建立通信了，不用在每次需要传输信息时重新建立连接，即不会“掉线”。json是数据存储格式，json数据可以方便的反序列化为Python数据。
接下来几个基础步骤，使用以下代码段更新您的pallet代码（如果您不想使用模板代码，请跳过此步骤）：
![cfg_attr(not(feature = "std"), no_std)]
pub use pallet::*;
[frame_support::pallet]
pub mod pallet {
use frame_support::pallet_prelude::*;
use frame_system::pallet_prelude::*;
use frame_support::{
sp_runtime::traits::Hash,
traits::{ Randomness, Currency, tokens::ExistenceRequirement },
transactional};
use sp_io::hashing::blake2_128;
[cfg(feature = "std")]
use frame_support::serde::{Deserialize, Serialize};
// ACTION #1: Write a Struct to hold Kitty information.
// ACTION #2: Enum declaration for Gender.
// ACTION #3: Implementation to handle Gender type in Kitty struct.
[pallet::pallet]
[pallet::generate_store(pub(super) trait Store)]
pub struct Pallet(_);
/// Configure the pallet by specifying the parameters and types it depends on.
[pallet::config]
pub trait Config: frame_system::Config {
/// Because this pallet emits events, it depends on the runtime's definition of an event.
type Event: From<Event<Self>> + IsType<<Self as frame_system::Config>::Event>;
/// The Currency handler for the Kitties pallet.
type Currency: Currency<Self::AccountId>;
// ACTION #5: Specify the type for Randomness we want to specify for runtime.
// ACTION #9: Add MaxKittyOwned constant}
// Errors.
[pallet::error]
pub enum Error {
// TODO Part III}
// Events.
[pallet::event]
[pallet::generate_deposit(pub(super) fn deposit_event)]
pub enum Event<T: Config> {
// TODO Part III}
[pallet::storage]
[pallet::getter(fn count_for_kitties)]
pub(super) type CountForKitties<T: Config> = StorageValue<_, u64, ValueQuery>;
// ACTION #7: Remaining storage items.
// TODO Part IV: Our pallet's genesis configuration.
[pallet::call]
impl<T: Config> Pallet {
// TODO Part III: create_kitty
// TODO Part IV: set_price
// TODO Part IV: transfer
// TODO Part IV: buy_kitty
// TODO Part IV: breed_kitty}
// Our helper functions.//
impl<T: Config> Pallet {
// ACTION #4: helper function for Kitty struct
// TODO Part III: helper functions for dispatchable functions
// ACTION #6: function to randomly generate DNA
// TODO Part III: mint
// TODO Part IV: transfer_kitty_to}
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}
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除了此代码，我们还需要导入serde 。将其添加到pallet的 Cargo.toml 文件中，使用匹配的版本作为substrate upstream。
