Unleash the Power of Interoperable Blockchains and Build the Future of Web3

The development process of a blockchain application requires extensive time. Not only that it requires different professionals to give their input in the development process. Developing on Polkadot tends to reduce this gap and simplify the development process. This guide will provide you with all the basic requirements so that you may start creating your project on Polkadot.

Overview of Polkadot

Polkadot is a blockchain protocol that delivers shared security among all the interconnected parachains. Interoperability is secured by layer 1 (L-1) blockchains known as parachains. The connected tasks may interoperate through XCM.
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Importance of Polkadot in the blockchain ecosystem

With the introduction of Polkadot along with Agile Coretime, the development time and time taken to launch the chain dropped significantly. Different blockchains can communicate easily with each other, making them work together and sharing security. Rather than depending solely on layer-2 scaling solutions, the parachain approach scales blockchain technology in a more decentralized and trustless manner. 'In-parallel' transactions occur concurrently on many blockchains protected by a single group of decentralized validators, dispersed throughout the network.
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Purpose of the guide

The guide is intended for blockchain enthusiasts, developers, and technology professionals curious about different technologies. The guide can provide valuable insights to anyone new to blockchain or someone with some experience with the blockchain.

What readers will learn

In this guide, we will get into details of what Polkadot is, its history, and what makes it valuable and distinctive from other blockchains. Moreover, the readers will become familiar with the architecture of the Polkadot. The readers will learn how the Polkadot is structured, including its unique relay chain and para chain setup. The readers will be driven through the setting up of the development environment to write their first Polkadot Runtime module. Additionally, readers will be introduced to more advanced concepts related to Polkadot such as consensus mechanisms that secure the network, the governance model that enables the stakeholders to actively participate in the decision-making process, XCM, forkless updates, and other advanced concepts.

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Before we dive deep into the development of Polkadot, we will give a brief on the foundations of Polkadot and its usability.

What is Polkadot?

History and Founding of Polkadot

Polkadot was founded by Dr. Gavin Wood who was a British computer scientist and the co-founder of Ethereum. The other founding members were Peter Czaban and Robert Habermeier. In October 2017, the Initial Coin Offering successfully generated more than $144.3 million. Launching with the genesis block in May 2020, Polkadot's native token, DOT, was made available. Wood has a vast history in blockchain as he was the one who invented solidity used for the coding of dApps on the Ethereum blockchain. 
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Key features and advantages

Some of the key features of the Ethereum blockchain are described below.

Interoperability

An important factor of the parachain design is that it enables the blockchain of different architectural setups to seamlessly communicate with each other. Due to this property, the blockchains are no longer considered to be isolated islands as they now have cross-chain composability and can share the security. This is done through a relay chain which acts as a central hub for all the para chains. The assets and data can move smoothly across various networks. Hence, there is no need for individual chains to develop their security mechanisms from scratch. As a result, the development process is sped up.
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Any type of data can be sent through the para chains and the transference is not limited to tokens only. The developers can come up with their own services that utilize multiple blockchains and can avoid the limitations of a single chain.
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Scalability

Polkadot offers a scalable framework that allows multiple blockchains to work in parallel. Polkadot is scalable at layer 1 which tends to be more decentralized than layer 2. Multiple transactions can be done in parallel which improves the efficiency and throughput over the non-sharded networks. Moreover, future considerations include optimizing Polkadot for improved scalability while keeping the concept of data availability, centralization, and security.
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Security

Polkadots have a shared security model and parachains get secure when they are connected to Polkadot. Normally, the security depends upon developing a network of validators which gets difficult and requires a lot of time. They may end up with a level of security that makes them vulnerable to attacks. Polkadot delivers a strong security model that prevents the network from any outside attacks. The relay chain is secured by a consensus mechanism called Nominated Proof-of-Stake (NPoS), where validators are chosen based on their stake in the network and their nominations from other stakeholders. This ensures that validators have a vested interest in maintaining the network's security and integrity. Additionally, the use of parachains allows individual chains to benefit from the shared security of the relay chain without compromising their own specialized functionalities.
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Shared security model

One thing that makes Polkadot unique is its shared security model. There is no need for independent security of each blockchain, the parachains connected to the Polkadot network share the same security enabling the new projects to set up their own protection from the outset without establishing their own validator networks. The system security is further strengthened when another parachain joins.

Understanding Polkadot's Architecture

Relay Chain

Role and function

The relay chain can be considered the most significant part of any Polkadot network as it is responsible for providing shared security for the network, consensus, and interoperability among various parachains. The Relay Chain is made up of a limited set of transaction types, such as NPoS participation, parachain auctions, and interactions with the governance mechanism. The relay chain enables the parachains to offload their security and threshold tasks. 
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Parachains

Typically, a Polkadot consists of 100 parachains interconnected and secured by a central relay chain. Let’s discuss what the purpose of a parachain is and some examples of existing parachains.
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Definition and purpose

Parachains are layer-one individual blockchains running in parallel with the Polkadot ecosystem. Parachains are able to host smart contracts. Polkadot is unable to host the smart contracts on its own. The goal of the Polkadot protocol is to build an interoperable blockchain network. This would enable autonomous blockchains to interact and cooperate with one another. The project's ultimate objective is to create a fully decentralized web. The DOT token is Polkadot's native cryptocurrency.
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Examples of existing parachains

Some examples of the existing parachains developed and deployed over the Polkadot network are listed below.

• Acala: A decentralized finance (DeFi) platform offering a suite of financial services, including a stablecoin, staking derivatives, and a decentralized exchange.
• Moonbeam: An Ethereum-compatible smart contract platform that allows developers to deploy existing Ethereum applications on Polkadot with minimal changes.
• Phala Network: A privacy-preserving cloud computing service that provides secure and scalable cloud infrastructure for decentralized applications.
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Parathreads

Parathreads are somewhat similar to parachains in a way that they are both independent and connected to the relay chain. However, they have some differences. Let's look into these references in a bit of detail.
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Difference between parachains and parathreads

Parathreads are operational on a pay-as-you-go model, while parachains have dedicated slots for continuous operations. They do not require a permanent slot on the relay chain and can be activated according to the requirements. They are a good option for projects that do not require constant access to the relay chain and are particularly beneficial for projects in the early stages of the network. Parathreads are lightweight and cost-effective as compared to parachains. Parathreads has a leasing model that enables them to lease the present relay chain slots, making it cost-effective as extensive resources are not required because of the constant connectivity. They have improved accessibility, which makes them suitable for small-scale startups and projects that do not require constant access, such as experimental projects. 
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Use cases for parathreads

Parathreads are well-suited for various scenarios:

• Development and Testing: Projects can use parathreads to test their blockchain applications without committing to a full parachain slot.
• Seasonal Applications: Applications that experience seasonal or intermittent usage can benefit from the cost-efficiency of parathreads.
• Niche Applications: Projects targeting niche markets with lower transaction volumes can use parathreads to remain cost-effective while still benefiting from Polkadot's security and interoperability.
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Bridges

Connecting different blockchains

Bridges are specialized protocols that enable Polkadot to connect with external blockchains, such as Ethereum, Bitcoin, and other networks. These bridges facilitate the transfer of assets and data between Polkadot and other blockchain ecosystems, enhancing the overall interoperability of the network.
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Importance of bridges for interoperability

Bridges play a significant role in making the blockchain ecosystem more interoperable as they allow seamless transference of assets and data across various chains, therefore increasing cross-chain communication and liquidity. Bridges enable users to access the features and services available on the other blockchains. They are able to manage the load across multiple blockchains by distributing it. Distribution of the load improves performance and prevents any congestion present on a single chain. They improve performance and efficiency by enabling less critical transactions to be processed on a less congested blockchain. Bridges are essential for the growth of decentralized finance (DeFi) by enabling cross-chain lending, borrowing, and trading, thus expanding the DeFi ecosystem. They facilitate the development of decentralized applications (DApps) that operate across multiple blockchains, offering more versatile and powerful solutions.
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Setting Up Your Development Environment

Let’s get started with the Polkadot development and the very first step to start with the development process is to set up the development environment in the first place. But before we go ahead with setting up the development environment, we will discuss some prerequisites required for the development process.
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Prerequisites

Before you start to set up your development environment for Polkadot development, make sure you have the following concepts intact.
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Basic programming knowledge

As far as development is concerned, the basic concepts of programming are required to start with the development process. You should not only be well familiar with the basic object-oriented concepts but also have foundational knowledge about languages such as JavaScript, Rust, or any other modern programming language. Basic knowledge of web development and software engineering will be helpful in Polkadot blockchain development.
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Understanding of Blockchain Concepts

You should have a basic understanding of blockchain technology, such as decentralized networks, consensus mechanisms, smart contracts, and how different blockchains communicate with each other. You should also have an idea of a distributed ledger and a decentralized application. 
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Tools and software required

Polkadot.js

Polkadot.js is a collection of tools and libraries for interacting with the Polkadot network. It includes a browser extension and a user-friendly web interface that allows developers to manage accounts, interact with smart contracts, and perform various blockchain-related tasks.
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Substrate

Substrate is a modular framework for building blockchains. Developed by Parity Technologies, it is the foundation of the Polkadot network. Substrate simplifies the process of creating custom blockchains and allows developers to leverage pre-built components while maintaining flexibility.
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Integrated Development Environment (IDE) setup (Visual Studio Code, etc.)

An Integrated Development Environment (IDE) is essential for efficient coding and debugging. Visual Studio Code is a popular choice due to its extensive library of extensions and robust support for multiple programming languages. Other IDEs like IntelliJ IDEA or Atom can also be used based on personal preference.
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Installation and configuration

Let’s start with the installation and configuration process. We will install each language and tool required for Polkadot development.
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Installing Substrate

Substrate is an SDK that enables programmers to build blockchains and tools for specific applications. Polkadot, a chain connecting several other blockchains, is compatible with blockchains constructed using Substrate. Normally, the substrate is built in Rust and runs on a Polkadot network. 
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Installation of Rust

First, Rust will be installed as it is required to build the substrate. The following command can be used to install Rust and set up the environment.

curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh

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After you have installed Rust, the next step is to configure your environment. That can be done through the following command.

source $HOME/.cargo/env
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Installation of Additional Dependencies

You may require a different set of dependencies based on the operational system you have. If you are working on Ubuntu, you may use the following commands for the installation of the required dependencies.

sudo apt update
sudo apt install -y git clang curl libssl-dev llvm libudev-dev
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Cloning of the Substrate Repository

Next, clone the Substrate node template from GitHub through the command.

git clone https://github.com/substrate-developer-hub/substrate-node-template
cd substrate-node-template
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Build the Node

Navigate to the node template directory and build the node through the command stated below.

cargo build --release
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Setting up the polkadot.js extension

Once you have installed the substrate, the next step is to install the polkadot.js extension. The steps to set up the extension are stated below.
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Installation of the Extension

Add the Polkadot.js extension to your browser (available for Chrome and Firefox). Search for "Polkadot.js" in your browser's extension store and install it.
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Creation of Account

After installing the extension, create a new account by following the on-screen instructions. Securely back up your mnemonic phrase.
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Connecting it to the Network

Use the Polkadot.js web interface to connect to the Polkadot network or a local Substrate node.
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Configuring the development environment

To configure the development environment, you should have a development environment installed on your system. You can configure your development environment in the following way.
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Installation of the Visual Studio Code

You may install any IDE to get started. It is convenient to use Visual Studio Code for the development. You may install the Visual Studio code from here.
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Installation of the Extensions

Make sure you have installed the required extensions, such as Rust, and Polkadot.js,  before you start the development process. The tools like prettier or Rustfmt can format your code and make it look neat and clean. Something that any professional coder will want.  
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Set up a New Project Directory

Set up a new project directory for your Polkadot development and configure the environment.

mkdir my-polkadot-project
cd my-polkadot-project
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Initialization of a New Substrate Node Template

You may initialize a new substrate node template through the following commands.

cargo install --force --locked cargo-substrate
substrate-node-new my-node
cd my-node
cargo build --release

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Make sure you have connected the substrate node to the Polkadot.js extension and the other extensions before you start your development.
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Cloning your Project

If you have a specific project or tutorial repository, clone it to your local machine:

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git clone <repository_url>
cd <project_directory>

Launching Your Project

You may now launch the Visual Studio code and open your project directory.
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Set Up Your Development Environment

You are all set to set up your development environment. Configure your IDE settings, including formatting rules, linting, and debugging configurations, to suit your workflow.

Introduction to Substrate

What is Substrate?

Substrate is a modular open-source framework for building customizable blockchains.
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Definition and purpose

Substrate is built by Parity Technologies to provide the foundation tools and benchmarks essential for developers to build and embed scalable, efficient blockchains. For me, Substrate is a high-level, general abstraction of a blockchain that allows someone to build a blockchain much faster and with less understanding of the actual code running underneath. Substrate is a set of pre-built libraries in high-level, abstract code that helps developers build their own custom blockchain from a template, rather than needing to start from scratch.
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Key components of Substrate

FRAME (Framework for Runtime Aggregation of Modularized Entities)

FRAME is the powerful and flexible framework of Substrate that lets you develop modular and reusable components, called pallets. These are the pallets that depict the base logic (functionality) of any blockchain itself (consensus mechanism, governance, token economics…) There are many pre-built pallets available from FRAME, aiding developers in quickly assembling custom solutions.
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Substrate Node

A Substrate node is the core component of a blockchain built with Substrate. It includes the runtime (the executable code of the blockchain), the networking layer, and the database. The node ensures that all participants in the network have a consistent view of the blockchain state and can process transactions and blocks according to the defined rules.
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Substrate Client

The Substrate client is the software that interacts with the Substrate node. It provides APIs and tools for developers to interact with the blockchain, including querying blockchain data, submitting transactions, and managing keys. The client is essential for building decentralized applications (DApps) that run on the blockchain.
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Building with Substrate

Writing custom pallets

Pallets are the building blocks of a Substrate-based blockchain's runtime. Writing custom pallets involves defining the specific logic and functionalities required by your blockchain application. This includes creating storage items, defining callable functions (extrinsics), and setting up event handlers. Here's a simple example of creating a custom pallet. Create a new pallet template through the code.

substrate-pallet-new my-pallet
cd my-pallet

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Next, define storage items and extrinsics in the lib.rs file of your pallet.

decl_storage! {
    trait Store for Module<T: Trait> as MyPallet {
        SomeValue get(fn some_value): u32;
    }
}

decl_module! {
    pub struct Module<T: Trait> for enum Call where origin: T::Origin {
        fn set_value(origin, value: u32) -> dispatch::DispatchResult {
            let _who = ensure_signed(origin)?;
            SomeValue::put(value);
            Ok(())
        }
    }
}

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In the above code,

• decl_storage! Macro:
• • Purpose: Defines storage items for the pallet.
  • Storage Item:
  • • SomeValue: A single u32 value stored in the blockchain.
  • Getter:
  • • get(fn some_value): Provides a function to retrieve the value of SomeValue.
• decl_module! Macro:
• • Purpose: Defines callable functions (extrinsics) for the pallet.
  • Function:
  • • set_value:
    • • Parameters: Takes origin (the caller) and value (a u32 value to store).
      • Ensures Origin: Verifies that the caller is a signed account (ensure_signed(origin)).
      • Action: Stores the provided value in SomeValue.
      • Returns: A DispatchResult, indicating success or failure of the operation.

After this step, you can implement the necessary traits and logic for your pallet.
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Integrating Pallets into Runtime

Once you are done writing your custom pallet, you can now integrate the written pallet into the blockchain’s runtime. However, this will require you to modify your runtime configuration. Doing so will ensure that the pallet interacts with the other components of the blockchain in the right way. 

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Here are the steps needed to integrate the pallets into the Runtime.

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• Step 1: Add your pallet to the runtime's Cargo.toml file.

[dependencies]
my-pallet = { path = '../my-pallet' }

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• Step 2: Include your pallet in the runtime's lib.rs file.

impl my_pallet::Trait for Runtime {
    type Event = Event;
}

construct_runtime!(
    pub enum Runtime where
        Block = Block,
        NodeBlock = opaque::Block,
        UncheckedExtrinsic = UncheckedExtrinsic
    {
        ...
        MyPallet: my_pallet::{Module, Call, Storage, Event<T>},
        ...
    }
);

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In the above code,

• Trait Implementation for Runtime:
• • Purpose: Integrates the custom pallet into the runtime.
  • Trait: Implements the my_pallet::Trait for the runtime.
  • Event Type: Specifies that the pallet will use the Event type defined in the runtime.
• construct_runtime! Macro:
• • Purpose: Assembles the runtime configuration, combining multiple pallets and their configurations.
  • Runtime Declaration:
  • • enum Runtime: Defines the main runtime type.
    • Block Types:
    • • Block: Standard block type.
      • NodeBlock: Opaque block type.
      • UncheckedExtrinsic: Type for unchecked extrinsics.
  • Pallet Integration:
  • • MyPallet:
    • • Includes the pallet's Module, Call, Storage, and Event<T> components.
      • Integrates the custom pallet (my_pallet) into the overall runtime, allowing it to participate in block processing and runtime operations.

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• Step 3: The final step is to build and test your runtime to ensure that the custom pallet is correctly integrated and functioning as expected.

Writing Your First Polkadot Runtime Module

Now that you have set up your environment and have an understanding of the substrate, you can write your first Polkadot runtime module.

Creating a new Substrate project

Your project should have several key directories and files that are needed for the proper functioning of a Polkadot project. 

Project structure

A typical substrate project has directories and files for runtime modules (pallets), the node, and the client. Here is what a typical Polkadot module structure looks like.

• /my-substrate-project: Root directory of the project.some text
• • /node: Contains the node implementation and configuration.
  • /runtime: Contains the runtime logic and modules.
  • /pallets: Custom pallets developed for the project.
  • Cargo.toml: Defines the Rust dependencies for the project.

Initial setup and configuration

Install Dependencies

Install all the required dependencies. Make sure that all the dependencies including rust are installed
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rustup update
rustup target add wasm32-unknown-unknown --toolchain nightly
cargo install --force --locked substrate

Create a New Substrate Node Template

Create a new substrate node template

substrate-node-new my-substrate-project
cd my-substrate-project

Initialize the Project

Initialize the project through the following command.

cargo build --release
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Open Your Project in Your Preferred IDE

Open the project in visual studio code or your preferred IDE.
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Developing the runtime module

To develop the module in runtime,the logic is written in Rust. 

Writing the logic in Rust

Create a New Pallet

• Create a New Pallet: Use the Substrate CLI to generate a new pallet.

substrate-pallet new my_pallet

This creates a new directory pallets/my_pallet with the basic structure

Define the Pallet

Open the lib.rs file in pallets/my_pallet/src and define your pallet's storage items, events, errors, and dispatchable functions.

#[frame_support::pallet]
pub mod pallet {
    use frame_support::{decl_module, decl_storage, decl_event, decl_error, dispatch};
    use frame_system::ensure_signed;

    #[pallet::pallet]
    #[pallet::generate_store(pub(super) trait Store)]
    pub struct Pallet<T>(_);

    #[pallet::config]
    pub trait Config: frame_system::Config {
        type Event: From<Event<Self>> + Into<<Self as frame_system::Config>::Event>;
    }

    #[pallet::storage]
    #[pallet::getter(fn something)]
    pub type Something<T> = StorageValue<_, u32>;

    #[pallet::event]
    #[pallet::generate_deposit(pub(super) fn deposit_event)]
    pub enum Event<T: Config> {
        SomethingStored(u32, T::AccountId),
    }

    #[pallet::error]
    pub enum Error<T> {
        NoneValue,
        StorageOverflow,
    }

    #[pallet::call]
    impl<T: Config> Pallet<T> {
        #[pallet::weight(10_000)]
        pub fn do_something(origin: OriginFor<T>, value: u32) -> dispatch::DispatchResult {
            let who = ensure_signed(origin)?;
            Something::<T>::put(value);
            Self::deposit_event(Event::SomethingStored(value, who));
            Ok(())
        }
    }
}

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In the above code,

• Pallet Declarationsome text
• • Declares a Substrate pallet module with #[frame_support::pallet].
• Importssome text
• • Imports necessary traits and macros from frame_support and frame_system.
• Pallet Structuresome text
• • Defines main structure with #[pallet::pallet].
  • pub struct Pallet<T>(_) serves as a placeholder for pallet storage and functions.
• Configuration Traitsome text
• • #[pallet::config] declares the configuration trait Config.
  • trait Config inherits from frame_system::Config.
  • type Event specifies event type for the pallet.
• Storage Declarationsome text
• • #[pallet::storage] declares storage item Something of type u32.
• Event Declarationsome text
• • #[pallet::event] declares events with SomethingStored(u32, T::AccountId).
• Error Declarationsome text
• • #[pallet::error] declares errors like NoneValue and StorageOverflow.
• Callable Functionssome text
• • #[pallet::call] declares callable function do_something.
  • Ensures origin is signed, stores value, emits SomethingStored event, and returns Ok(())

2. Compiling and testing the module

Build the Project

Compile the project to ensure there are no errors.

cargo build --release

Run Unit Tests

Write unit tests for your pallet and run them to verify functionality.

#[cfg(test)]
mod tests {
    use super::*;
    use frame_support::{assert_ok, assert_err};

    #[test]
    fn it_works_for_default_value() {
        new_test_ext().execute_with(|| {
            // Dispatch a signed extrinsic.
            assert_ok!(TemplateModule::do_something(Origin::signed(1), 42));
            // Read pallet storage and assert an expected result.
            assert_eq!(TemplateModule::something(), Some(42));
        });
    }
}

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In the above code,

• Test Module Declarationsome text
• • #[cfg(test)] mod tests declares a module for tests.
• Importssome text
• • Imports necessary items from the parent module and frame_support.
• Test Functionsome text
• • #[test] fn it_works_for_default_value() defines a test function.
• Test Executionsome text
• • new_test_ext().execute_with(|| { ... }) sets up a test environment and executes the closure.
• Dispatch and Assertionsome text
• • assert_ok!(TemplateModule::do_something(Origin::signed(1), 42)) checks if the do_something function executes successfully with 42 as the value.
  • assert_eq!(TemplateModule::something(), Some(42)) checks if the storage item Something equals 42.

Make sure to run the tests through the command.

cargo test

Deploying the runtime module

Deploying to a local testnet

Start a Local Node

Use the Substrate node template to start a local testnet.

./target/release/node-template --dev
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Integrate the Pallet

Add your custom pallet to the runtime configuration in runtime/src/lib.rs.

impl my_pallet::Config for Runtime {
    type Event = Event;
}

construct_runtime!(
    pub enum Runtime where
        Block = Block,
        NodeBlock = opaque::Block,
        UncheckedExtrinsic = UncheckedExtrinsic
    {
        ...
        MyPallet: my_pallet::{Pallet, Call, Storage, Event<T>},
    }
);

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In the above code,

• Implement Configuration Traitsome text
• • impl my_pallet::Config for Runtime implements the Config trait for my_pallet within the Runtime.
  • type Event = Event sets the event type for my_pallet to the runtime's event type.
• Construct Runtimesome text
• • construct_runtime! macro defines the runtime configuration.
  • pub enum Runtime declares the Runtime enum with associated types.
  • MyPallet: my_pallet::{Pallet, Call, Storage, Event<T>} includes my_pallet in the runtime, specifying its pallet, call, storage, and event types.

Rebuild and Run the Node

Rebuild the node with your integrated pallet.

cargo build --release
./target/release/node-template --dev

Interacting with the deployed module

You can use the Polkadot.js web interface for the connection to the local node. The Polkadot.js UI can be used for the submission of transactions to the custom pallet. To interact with your deployed module:

• Step 1: Use the Polkadot.js Apps UI to connect to your local node.
• Step 2: Navigate to the extrinsics tab to call the set_value function.
• Step 3: Submit the transaction and verify the storage update.

Advanced Polkadot Development Concepts

In this section, we will discuss some of the advanced Polkadot concepts required in the Polkadot development.

Cross-chain communication

XCM (Cross-Consensus Messaging)

XCM also known as cross-consensus messaging is a protocol that helps to develop communication between different blockchains within the Polkadot ecosystem. It helps achieve seamless communication between parachains, relay chains, and external blockchains.
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Components of XCM

• Messages: Structured data packets that contain the information to be transferred.
• Translators: Components that convert messages into a format understandable by the target chain.
• Relayers: Nodes or services responsible for forwarding messages between chains.
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Benefits of XCM

• Interoperability: Allows different chains to work together, sharing data and functionality.
• Scalability: Distributes workload across multiple chains, reducing congestion on any single chain.
• Efficiency: Facilitates efficient asset transfers, reducing the need for intermediaries.

Implementing cross-chain interactions

Understanding the XCM Language

To implement the cross-chain interactions, you should be well familiar with the XCM format and its syntax. Detailed information on the operations, types, and structures is present in the XCM documentation. 
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Setting Up the XCM Pallets

Next, you want to set up the XCM pallets by connecting them to your parachain. These will be responsible for the sending, receiving, and execution of XCM messages. Here is a code snippet showing how you may set up your XCM messages.

impl xcm::Config for Runtime {
    type Call = Call;
    type XcmSender = XcmRouter;
    type ExecuteXcmOrigin = EnsureXcmOrigin<Self::Origin, LocalOriginToLocation>;
    // additional configurations
}

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In the above code,

• Implement XCM Configuration Traitsome text
• • impl xcm::Config for Runtime implements the xcm::Config trait for Runtime.
• Associated Typessome text
• • type Call = Call: Specifies the Call type used by XCM.
  • type XcmSender = XcmRouter: Specifies the type used to send XCM messages.
  • type ExecuteXcmOrigin = EnsureXcmOrigin<Self::Origin, LocalOriginToLocation>: Specifies the origin type for executing XCM, ensuring it is a valid XCM origin.
• Additional Configurationssome text
• • Placeholder comment indicating there are more configuration options to be defined.

Create and Dispatch XCM Messages

To build and send messages, the XCM APIs can be used. This might include moving assets around or calling functions on a chain that is not local.

let message = Xcm(vec![
    TransferAsset {
        asset: MultiAsset {
            id: AssetId::Concrete(MultiLocation::new(1, X1(Parachain(1001)))),
            fun: Fungibility::Fungible(10_000),
        },
        effects: vec![
            DepositAsset {
                assets: All,
                max_assets: 1,
                beneficiary: MultiLocation::new(1, X1(AccountId32 { id: to_account, network: Any })),
            }
        ]
    }
]);

xcm_pallet::send_xcm(dest, message);

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In the above code,

• Create XCM Messagesome text
• • let message = Xcm(vec![ ... ]) creates an XCM message encapsulated in a vector.
• TransferAsset Instructionsome text
• • TransferAsset { ... } defines an instruction to transfer an asset.
  • asset: MultiAsset { ... } specifies the asset to be transferred:some text
  • • id: AssetId::Concrete(MultiLocation::new(1, X1(Parachain(1001)))): Identifies the asset location, in this case, a specific parachain (1001).
    • fun: Fungibility::Fungible(10_000): Specifies the asset as fungible with an amount of 10,000 units.
• Effects of Transfersome text
• • effects: vec![ ... ] lists the effects of the transfer.
  • DepositAsset { ... } defines an effect to deposit the asset:some text
  • • assets: All: Indicates all assets are to be deposited.
    • max_assets: 1: Sets a limit of 1 asset to be deposited.
    • beneficiary: MultiLocation::new(1, X1(AccountId32 { id: to_account, network: Any })): Specifies the beneficiary location and account ID.
• Send XCM Messagesome text
• • xcm_pallet::send_xcm(dest, message): Sends the XCM message to the specified destination (dest).

Handle Incoming Messages

Implement logic in your parachain to process and respond to incoming XCM messages.

impl xcm_executor::Config for Runtime {
   type XcmSender = XcmRouter;
   type AssetTransactor = MultiCurrencyAdapter<Balances, ...>;
   type LocationInverter = LocationInverter<Ancestry>;
   type OriginConverter = LocationConverter;
   type IsReserve = NativeAsset;
   type IsTeleporter = NativeAsset;
   type Barrier = AllowUnpaidExecutionFrom<Everything>;
   type Weigher = FixedWeightBounds<UnitWeightCost, Call, MaxInstructions>;
   type Trader = FixedRateOfConcreteFungible<WeightPrice>;
   type ResponseHandler = ();
}

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In the above code,

• XCM Executor Configurationsome text
• • Implements xcm_executor::Config for Runtime.
• Key Configurationssome text
• • XcmSender = XcmRouter: Router for sending XCM messages.
  • AssetTransactor = MultiCurrencyAdapter<Balances, ...>: Handles asset transactions.
  • LocationInverter = LocationInverter<Ancestry>: Manages locatioinversion.
  • OriginConverter = LocationConverter: Converts origin locations.
  • IsReserve = NativeAsset: Identifies reserve assets.
  • IsTeleporter = NativeAsset: Identifies teleportable assets.
  • Barrier = AllowUnpaidExecutionFrom<Everything>: Allows unpaid execution.
  • Weigher = FixedWeightBounds<UnitWeightCost, Call, MaxInstructions>: Calculates weight.
  • Trader = FixedRateOfConcreteFungible<WeightPrice>: Sets trading rates.
  • ResponseHandler = (): No specific response handler.

Upgrading the runtime

On-chain governance

On-chain governance permits stakeholders to have a voice in decision-making directly via the blockchain. That is, it enables the network to be upgraded or altered in a manner that is transparent and democratic.

Components of On-Chain Governance

• Council: A panel of elected representatives tasked with suggesting amendments and reaching resolutions.
• Referenda: Voting mechanisms through which token holders can vote on the changes proposed.
• Treasury: This is a fund managed by on-chain governance for financing the development and maintenance of the network.

Implementing On-Chain Governance

• Governance Pallets: Include governance pallets like pallet-democracy, pallet-collective, and pallet-treasury.

impl pallet_democracy::Config for Runtime {
    type Proposal = Call;
    type Event = Event;
    type Currency = Balances;
    // additional configurations
}
‍

Proposing Changes

Stakeholders may suggest changes through referenda. The community has the option to vote on the proposals.

let proposal_hash = frame_system::Pallet::<Runtime>::remark(vec![...]).hash();
let deposit = <Democracy as pallet_democracy::Trait>::Currency::minimum_balance() * 5;
Democracy::propose(origin, proposal_hash, deposit);
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Voting

Community members vote on proposals using their staked tokens.

Democracy::vote(origin, referendum_index, AccountVote::Standard {
    vote: Vote { aye: true, conviction: Conviction::Locked1x },
    balance: 10_000,
});

Benefits

• Transparency: The blockchain keeps records of all resolutions and polls.
• Decentralization: It cuts down on the necessity of central authority and gives every participant some control.

Forkless upgrades

Definition

The blockchain can be updated without splitting the network into different versions (forks) through forkless upgrades. This is done by means of the built-in upgrade mechanisms of the runtime.

Steps for Forkless Upgrades:

‍

• Propose an Upgrade: Through on-chain governance, stakeholders propose upgrades
• Vote on the Proposal: Token holders vote using referenda for or against the proposal.
• Implement the Upgrade: If the proposal is successful, the new runtime code will be deployed and activated automatically.

Implementation

• Runtime Upgrades

Use the frame_system: Pallet to propose and execute runtime upgrades through governance.

let wasm_binary = include_bytes!("../runtime/wasm/target/wasm32-unknown-unknown/release/runtime.wasm").to_vec();
let code = wasm_binary.to_vec();
System::set_code(frame_system::RawOrigin::Root.into(), code);

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• Automatic Upgrades

The network automatically applies the new runtime code after a successful governance vote.

frame_support::dispatch::result::Result::Ok(())

Benefits

• Continuity: It prevents disruptions in the network and keeps it as one chain.
• Efficiency: Fixes and features can be deployed quickly.

Security considerations

Writing secure code

Best Practices

‍

• Audit and Review: Perform regular audits and peer reviews of the code to find and fix security vulnerabilities.
• Testing: Conduct thorough tests such as unit tests, integration tests, and fuzz testing.
• Use Libraries and Frameworks: Use reliable libraries and frameworks that have strong security features built in.

Secure Coding Practices

• Input Validation: Check and clean all inputs to prevent injection attacks.
• Access Control: Employ strict access control methods that limit unauthorized entry.
• Error Handling: Employ proper error handling techniques so as not to expose sensitive information.

Common vulnerabilities and mitigations

Examples

• Reentrancy Attacks: Prevent reentrancy by using checks-effects-interactions patterns.
• Integer Overflow/Underflow: Use safe math libraries to handle arithmetic operations.
• Denial of Service (DoS): Optimize code to prevent long-running operations and implement rate limiting.

Mitigations

• Use of SafeMath: Employ SafeMath or similar libraries to handle arithmetic operations securely.
• Gas Limitations: Set appropriate gas limits to prevent DoS attacks from long-running transactions.

Regular Updates: Keep dependencies and libraries up to date to mitigate known vulnerabilities.

Official documentation and guides

Polkadot documentation

The Polkadot documentation serves as a comprehensive guide covering all the essential information about Polkadot development. The documentation covers the basic concepts, the advanced features, and the technicalities of the Polkadot ecosystem. It is divided into different categories including Polkadot Wiki, Polkadot Spec, and Substrate Docs which serve as a guideline for the development of Polkadot, maintaining projects on it, and participation in governance. Furthermore, some additional resources are also available on it. The documentation can be accessed through this link. 
‍

Substrate documentation

The framework on which Polkadot is built has its own detailed documentation. The Substrate documentation covers the basic concepts and terminologies of blockchain, step-by-step tutorials to detailed technical guides for a firsthand experience in building one’s own blockchain from a template, and the documentation also covers the understanding of the Substrate’s inner workings. You can access the Substrate documentation here. 
‍

Online courses and tutorials

Recommended courses for Polkadot development

There are a variety of online courses available that can help you get started with Polkadot development:

• Web3 Foundation MOOCs: The courses offered by the Web3 Foundation cover the basic concepts of blockchain technology, cryptography, Crypto wallets, NFTs, and networks. They also offer a course on the introduction to Polkadot that covers a comprehensive overview of the Polkadot network, technology, and its ecosystem. These courses are offered for free and can be accessed at here. 

‍

• The Polkadot Blockchain Academy: It is a collection of classroom and online-based educational programs focused on Polkadot and its ecosystem. It includes modules on different aspects of Polkadot development including Cryptography, core blockchain concepts, smart contracts, Polkadot-SDK, and their system of governance. This course is offered for free for the selected candidates and more information can be found here about this course.

‍

• Polkadot Blockchain Developer Bootcamp with Substrate + Rust: This course offered on Udemy can be utilized to learn everything about the basics of Blockchain, Polkadot, networks, Substrate, and nodes. The course can be accessed through this link which will cost a total of $59.99.

‍

• Certified Polkadot Expert: The Blockchain Council is offering a course and certification that is going to cover the Polkadot system and give a better understanding of how a Polkadot works, how different applications can be built by using Polkadot, and its comparison with other blockchains. It is an exam-based certification that will provide a skill set to excel in the world of Polkadot. The course along with the certification after the exam will cost $229 and further information can be obtained from this link. 

‍

2. Tutorials and hands-on labs

Getting hands-on labs and tutorials is a key to practical learning. In order to get started, here are some of the useful resources:

• Polkadot Wiki: This resource contains step-by-step guides and tutorials covering a range of tasks on Polkadot. Different areas about the blockchain and Polkadot are covered here such as setting up nodes, creating parachains, or the use of governance tools which can be found helpful. The tutorials can be found here. 

‍

•  Substrate tutorials: To gain hands-on experience in building your own blockchain and focus on ensuring a successful result, substrate documentation can be useful. It includes a series of tutorials that cover the basics of building your own blockchain, building application logic, building a parachain, and basic setup to advanced customization. Explore them here. 

‍

• Blockchain Training Alliance: The Blockchain Training Alliance is offering courses including comprehensive labs by the name of “Developing on Polkadot with Substrate”. It is designed for developers to learn effective building on Polkadot. The students in this course will learn how the Polkadot platform works, understand governance and treasury processes, and have a hands-on lab environment for writing code. Details about the course and the hands-on lab can be accessed here. 

‍

Community and support

Online forums and communities

Active involvement in the community is important for learning and receiving support. Here are some key forums and communities for Polkadot developers:

• Polkadot Discord: This community hub on Discord provides a platform for Polkadot developers to ask questions, share knowledge, and collaborate with other developers. Join the Polkadot Discord community through this link. 

‍

• Polkadot Reddit: The dot subreddit is a dedicated community for Polkadot developers. It is a dedicated forum for discussing Polkadot-related topics, sharing news, and seeking help from other developers when needed. Visit the Polkadot Reddit community here. 

‍

• The Polkadot Forum: It is a dedicated forum for the discussions surrounding Polkadot and Kusama. You can read and discuss topics related to Polkadot, create and contribute to topics related to it, form groups with other contributors, ask for feedback about your work, and organize and be a part of different discussions related to Polkadot. You can be a part of this forum and access it through this link. 

‍

• Developer Heroes Program: To unite a growing ecosystem for building a better web, Polkadot is working on attracting a community of developers to work on creating a new Polkadot Developer Heroes Program. The goal of the program is to build a strong community of Polkadot developers from newcomers to experts, for the growth and evolution of the Polkadot ecosystem, and to recognize, support, and elevate outstanding developers. The program is set to be launched soon and more information about it can be found here.

Attending meetups and conferences

Participating in meetups and conferences can provide valuable networking opportunities and suggestions from experts. These are some of the opportunities that you can take advantage of.

• Polkadot Decoded: It is an annual conference dedicated to blockchain and Polkadot. This conference features talks, workshops, and network sessions for developers to learn from and know more developers. It is a great way to be up to date on the latest developments on blockchains and Polkadot and connect with the community.

‍

• Local Meetups: Explore local blockchain and Polkadot meetups around you. These events provide a casual environment to learn and connect with fellow developers.

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By utilizing these resources, you can have a deeper understanding of blockchain and Polkadot, enhance your development skills, and become an active member of the Polkadot community and contribute to it.

Conclusion

This tutorial has covered the most important aspects of Polkadot development, starting with the core idea of the platform itself: facilitating the creation of a decentralized web through interoperability, adaptability, and multiple-chain governance. We have talked about setting up your development environment,  this includes installing essential tools such as Rust, Substrate, and Polkadot.js while also configuring your IDE to fit those needs. It is important that you lay down a strong base before embarking on any coding journey. 

‍

To write your first Polkadot runtime module, you needed to create a new Substrate project, structure the codebase well, and implement custom runtime logic in Rust. It was also crucial that you integrated and tested this module before deployment for it to work properly and be reliable. Furthermore, we touched on advanced concepts like using XCM for cross-chain communication, updating the runtime through on-chain governance without forks, as well as keeping very high-security standards. All these ideas are essential when building powerful and scalable applications on Polkadot. 

‍

Testing and Debugging were important parts which we covered by stressing the need for unit tests with Substrate’s test framework, using common debugging techniques, and setting up CI/CD pipelines for automated testing and deployment. It is necessary to ensure that your code has been thoroughly tested and debugged before you deliver it into production if you want success in your project. 

‍

To deploy your dApp on Polkadot, there are several things that must be done such as final testing and optimization. We also discussed deploying parachains/parathreads and post-deployment concerns including monitoring, analytics, or user feedback handling to make sure they stay functional and continue meeting user needs. Best practices in Polkadot development were mentioned where we talked about organizing code around modularity and efficiency, following secure coding guidelines, and tuning performance among others. These practices are aimed at maintaining high standards of software quality and performance throughout its life cycle. 

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Finally, never stop learning — always look out for more resources and community support. You can find these in official Polkadot or Substrate documentation, online courses and tutorials as well as active community forums where people ask questions daily. It’s through engaging with such materials that one gets updated with current trends while also improving their skills constantly.

‍

If you are planning to continue your journey on Polkadot development, keep in mind that the world of blockchain never stops changing. Always be inquisitive, don’t cease to try different options, and interact with the public regularly to learn more. Its originality in construction and concentration on a scalable architecture that supports interoperability as well as decentralization through governance reflect Polkadot’s crucial role among distributed programs which will be created in days ahead. By familiarizing yourself and getting involved with fellow developers you will prepare for what lies ahead; this could mean everything from contributing towards this cause or gaining something out of it depending on how much effort one puts into such activities. Learn additional information on Polkadot by referring to the official Polkadot documentation or Substrate documentation for more enlightenment.

FAQs

A. What is the main purpose of Polkadot?

Polkadot is a protocol that connects different blockchains and allows value and data to be sent across them as well. The main purpose of Polkadot is to build a completely decentralized web by facilitating interoperability, flexibility, and governance across multiple blockchains.

B. What are the key features of Polkadot that make it suitable for dApp development?

The main key features that make Polkadot suitable for dApp development include it ability to work between different blockchains within the Polkadot ecosystem which enables the different blockchains to communicate with each other, its ability to be flexible with the Polkadot’s framework, Substrate, and also providing the dApp developers an ability to focus on building solutions without worrying about security issues. The Polkadot decentralized governance model also enables the dApp developers to participate in decision-making processes.

C. How do I get started with writing my first Polkadot runtime module?

To kick off writing your first runtime module on Polkadot, there are the steps to follow:

Setup Your Development Environment

• Install Rust and set up the Substrate framework
• Create a new Substrate project using the Substrate Node Template

Develop the Runtime Module

• Use decl_storage! and decl_module! macros to define storage and extrinsic properties
• Write the necessary logic and functionality for your module

Integrate and Test

• Allocate your module into the runtime
• Write tests for your module and ensure they pass

Deploy and Interact

• Deploy your module on a local testnet
• Interact with your module using Polkadot.js Apps among other tools

D. What are some best practices for Polkadot development?

Some of the best practices for Polkadot coding are­:

• Keep your code ne­at and separated into parts.
• Use code­ parts you can use again and code libraries.
• This he­lps keep your code cle­an and working well.
• Follow safe coding rules like­ checking inputs and controlling access.
• Check your code­ often to find and fix any security issues.
• Make­ your code run fast and efficiently.
• Use­ special Polkadot features like­ parallel processing to boost performance­.
• Join the Polkadot community on forums, Discord, and meetups. Stay update­d and get help there­.

E. Where can I find additional resources and community support for learning Polkadot?

You can find additional resources and community support for learning Polkadot in the following places:

1. Official Documentation:some text
2. • Polkadot Documentation
   • Substrate Documentation
2. Online Courses and Tutorials:some text
3. • Blockchain Fundamentals MOOC
   • Polkadot Wiki Tutorials
3. Community and Support:some text
4. • Polkadot Discord
   • Polkadot Reddit
   • Attend events like Polkadot Decoded and local meetups

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