ICON – TCP / IP of Blockchain platform?

Sunday, 30/08/2020

Tram Ho

1. Introduction

ICON is a Blockchain 2.0 platform (which has many similarities with Ethereum). ICON runs smart contracts with a Delegated Proof-of-Stake (BFT-DPoS) consensus protocol, a cryptocurrency on the ICON network called ICX .

The goal of the ICON development team in the future is to connect blockchain networks with each other, making them easy to exchange assets as well as data. There is an example that the ICON development team gave to compare the interconnection of blockchain networks, like the advent of the TCP / IP protocol suite that connects private networks to each other into the Internet. Global. ICON wants them to be the TCP / IP of Blockchain

About the world is an introduction video about ICON from the developer team

2. Some basic concepts

Account

Like Ethereum, ICON also has 2 types of accounts:

Externally Owned Accounts: Starting with hx , 20 hex bytes in length
Smart contract accounts: Start with cx , 20 hex bytes in length. No private key available.

Deal

Types of transactions on ICON

Transfer ICX
Save data to blockchain
Deploy or update SCORE
Change the state of SCORE

Note : Smart contract on ICON is called SCORE

The parameters when executing a transaction:

from : Address to create transaction
to : Transaction receiving address (When deploying, the receiving address is cx0000000000000000000000000000000000000000 )
value : The amount of ICX sent
stepLimit : Maximum number of steps a transaction can take (similar to gasLimit in Ethereum)
time stamp : The time to create a transaction
nonce : Transaction number of sending account (similar to nonce in Ethereum)
nid : Network ID (Distinguishing between mainnet, testnet)
data type : Helps distinguish transaction types. Includes 3 values call , deploy and message . With a normal ICX transfer, the data type is ignored.
data : Transaction content (can be the parameters passed to call the function in the contract)
signature : The digital signature of the sender of the transaction
transaction hash : The hash value that identifies the transaction

Transaction fee

Step is the unit of measurement for calculating transaction fees on the ICON network. The number of steps a transaction takes depends on the amount of compute resources it takes to execute the transaction. Initial Rate, 1 ICX = 100,000,000 Step . This rate can be changed if the ICX price rises too high or is dropped very low.

Formula for calculating step

Step = max (∑ βiSi + C, C)

Note : The maximum number of steps a transaction can consume is 2.5 billion steps

With:

Si is the number of times a particular call comes to the smart contract.
βi is the number of steps that will be consumed with each specific call.
C is the minimum number of steps a transaction needs to pay (Constant with a value of 100,000)

Below are 2 tables that describe the possible values of Si and the step values consumed with each corresponding call to the contract.

Policy support transaction fees for users

Normally, when making a transaction, the user will bear the full cost. With ICON, the development team designed a feature that allows contract owners to support part or all of the transaction costs when users call their contracts.

Percentage of support fees ranges from 0 – 100% (meaning fees may not be subsidized). If the contract developer wants to support fees for users, they must send an amount of ICX in advance to the contract so that when the user calls, this amount of ICX will be deducted from the user’s transaction fee depending on the rate.

Virtual Step

Virtual Step is the new fee system of the ICON network for contract owners. It is created monthly corresponding to the number of ICX sent to the contract and the period of time ICX is deposited into that contract. In addition to supporting fees for users using ICX , SCORE owners can pay fees in Virtual Step . This helps contract owners reduce part of the cost burden as well as encourage the higher percentage of support fees for users.

Some features:

Virtual Step and Step have a 1: 1 ratio
Virtual Step is created every 1,296,000 blocks (1 month). At that time, unused Virtual Steps will expire.
Virtual Step cannot be moved anywhere.
Support fee for users will spend Virtual Step first, if the Virtual Step runs out, then ICX will be spent

Calculating the Virtual Step

When sending ICX into the contract, it is necessary to set the deposit amount and the deposit period.
Delivery times can be set from a minimum of 1 month to a maximum of 24 months.
Minimum deposit amount is from 5,000 ICX up to maximum 100,000 ICX.

Depending on the short or long deposit period, the number of viral steps received after each month will vary:

For example:

Send 10,000 ICX in with a period of 1 month. Each month receiving 80,000,000,000 Virtual Step, equivalent to 8% of the 10,000 deposit amount, is 800 ICX.
Send 10,000 ICX in with a 24-month period. Each month receives 202,400,000,000 Virtual Step, equivalent to 20.24% of the deposit amount of 10,000 ICX.

Note : Contract holders will be subject to a penalty if they withdraw their deposited ICX before the end of the predetermined period. The fine is the total number of Virtual Steps used in the previous period.

ICON nodes

ICON nodes have 3 types

Peer: can participate in consensus protocol, can create new block on the network.
Citizen: Blockchain data synchronization and transaction forwarding to Peer.
Light: Save the block header of the network, perform the task of transaction verification.

3. Write smart contract

SCORE on ICON is written in Python language.

First, you need to install the tbears tool, tbears is a tool to initiate, deploy and interact with smart contracts on the ICON network (similar to the truffle on Ethereum). The tbears settings can be found here

Hello world

We’ll start with the simplest smart contract

Step 1 : Initialization

<span class="token comment"># tbears init [project_name] [main_class_name]</span>
tbears init hello HelloWorld

# tbears init [project_name] [main_class_name]

tbears init hello HelloWorld

In the newly created folder hello , we will see 3 files

__init.py__ : Initially empty, this file helps the Python interpreter to recognize this folder as a package.
hello.py : The main FIle, which contains the logic of the contract
package.json : This file contains the basic information of the contract such as version, name, …

<span class="token comment">// package.json</span>
<span class="token punctuation">{</span>
	<span class="token string">"version"</span> <span class="token operator">:</span> <span class="token string">"0.0.1"</span> <span class="token punctuation">,</span>
	<span class="token string">"main_module"</span> <span class="token operator">:</span> <span class="token string">"hello_world"</span> <span class="token punctuation">,</span>
	<span class="token string">"main_score"</span> <span class="token operator">:</span> <span class="token string">"HelloWorld"</span>
<span class="token punctuation">}</span>

// package.json

{

"version" : "0.0.1" ,

"main_module" : "hello_world" ,

"main_score" : "HelloWorld"

}

<span class="token comment"># hello-world.py</span>
<span class="token keyword">from</span> iconservice <span class="token keyword">import</span> <span class="token operator">*</span>

TAG <span class="token operator">=</span> <span class="token string">'HelloWorld'</span>

<span class="token comment"># class HelloWorld kế thừa class IconScoreBase của thư viện iconservice</span>
<span class="token keyword">class</span> <span class="token class-name">HelloWorld</span> <span class="token punctuation">(</span> IconScoreBase <span class="token punctuation">)</span> <span class="token punctuation">:</span>
	<span class="token comment"># Hàm __init__ là hàm constructor của class, được gọi khi nào contract được deploy mới </span>
	<span class="token keyword">def</span> <span class="token function">__init__</span> <span class="token punctuation">(</span> self <span class="token punctuation">,</span> db <span class="token punctuation">:</span> IconScoreDatabase <span class="token punctuation">)</span> <span class="token operator">-</span> <span class="token operator">&gt;</span> <span class="token boolean">None</span> <span class="token punctuation">:</span>
	  <span class="token builtin">super</span> <span class="token punctuation">(</span> <span class="token punctuation">)</span> <span class="token punctuation">.</span> __init__ <span class="token punctuation">(</span> db <span class="token punctuation">)</span>
     
	<span class="token comment"># Hàm on_install chỉ được gọi 1 lần khi deploy contract lần đầu</span>
	<span class="token comment"># Khi contract được update thì nó không được gọi lại nữa</span>
	<span class="token keyword">def</span> <span class="token function">on_install</span> <span class="token punctuation">(</span> self <span class="token punctuation">)</span> <span class="token operator">-</span> <span class="token operator">&gt;</span> <span class="token boolean">None</span> <span class="token punctuation">:</span>
	  <span class="token builtin">super</span> <span class="token punctuation">(</span> <span class="token punctuation">)</span> <span class="token punctuation">.</span> on_install <span class="token punctuation">(</span> <span class="token punctuation">)</span>
      
	<span class="token comment"># Hàm on_update được gọi khi contract được update </span>
	<span class="token keyword">def</span> <span class="token function">on_update</span> <span class="token punctuation">(</span> self <span class="token punctuation">)</span> <span class="token operator">-</span> <span class="token operator">&gt;</span> <span class="token boolean">None</span> <span class="token punctuation">:</span>
	  <span class="token builtin">super</span> <span class="token punctuation">(</span> <span class="token punctuation">)</span> <span class="token punctuation">.</span> on_update <span class="token punctuation">(</span> <span class="token punctuation">)</span>
      
	<span class="token comment"># Hàm hello sẽ trả về thông điệp "Hello" bất cứ khi nào được gọi</span>
	<span class="token decorator annotation punctuation">@external</span> <span class="token punctuation">(</span> readonly <span class="token operator">=</span> <span class="token boolean">True</span> <span class="token punctuation">)</span>
	<span class="token keyword">def</span> <span class="token function">hello</span> <span class="token punctuation">(</span> self <span class="token punctuation">)</span> <span class="token operator">-</span> <span class="token operator">&gt;</span> <span class="token builtin">str</span> <span class="token punctuation">:</span>
	  Logger <span class="token punctuation">.</span> debug <span class="token punctuation">(</span> f <span class="token string">'Hello, world!'</span> <span class="token punctuation">,</span> TAG <span class="token punctuation">)</span>
	  <span class="token keyword">return</span> <span class="token string">"Hello"</span>

# hello-world.py

from iconservice import *

TAG = 'HelloWorld'

# class HelloWorld kế thừa class IconScoreBase của thư viện iconservice

class HelloWorld ( IconScoreBase ) :

# Hàm __init__ là hàm constructor của class, được gọi khi nào contract được deploy mới

def __init__ ( self , db : IconScoreDatabase ) - > None :

super ( ) . __init__ ( db )

# Hàm on_install chỉ được gọi 1 lần khi deploy contract lần đầu

# Khi contract được update thì nó không được gọi lại nữa

def on_install ( self ) - > None :

super ( ) . on_install ( )

# Hàm on_update được gọi khi contract được update

def on_update ( self ) - > None :

super ( ) . on_update ( )

# Hàm hello sẽ trả về thông điệp "Hello" bất cứ khi nào được gọi

@external ( readonly = True )

def hello ( self ) - > str :

Logger . debug ( f 'Hello, world!' , TAG )

return "Hello"

Implement Token

ICON supports implementation of many different token standards (with reference to the ERC standards of Ethereum), ICON ‘s token standards are defined here.

In this example, we will try implementing the standard IRC-2 token, which is the Fungibles Token form (IRC-2 is a reference to the ERC-20 and ERC-223 standard of Ethereum). The definition of the IRC-2 standard can be found here

tbears init sample-token SampleToken
` <span class="token variable"><span class="token variable">`</span>

<span class="token variable">`</span></span> ` <span class="token variable"><span class="token variable">`</span> py
<span class="token comment"># sample_token.py</span>
from iconservice <span class="token function">import</span> *

TAG <span class="token operator">=</span> <span class="token string">'SampleToken'</span>

<span class="token comment">## Định nghĩa interface theo chuẩn IRC-2</span>
class TokenStandard:
    @abstractmethod
    def name <span class="token punctuation">(</span> self <span class="token punctuation">)</span> - <span class="token operator">&gt;</span> str:
        pass

    @abstractmethod
    def symbol <span class="token punctuation">(</span> self <span class="token punctuation">)</span> - <span class="token operator">&gt;</span> str:
        pass

    @abstractmethod
    def decimals <span class="token punctuation">(</span> self <span class="token punctuation">)</span> - <span class="token operator">&gt;</span> int:
        pass

    @abstractmethod
    def totalSupply <span class="token punctuation">(</span> self <span class="token punctuation">)</span> - <span class="token operator">&gt;</span> int:
        pass

    @abstractmethod
    def balanceOf <span class="token punctuation">(</span> self, _owner: Address <span class="token punctuation">)</span> - <span class="token operator">&gt;</span> int:
        pass

    @abstractmethod
    def transfer <span class="token punctuation">(</span> self, _to: Address, _value: int, _data: bytes <span class="token operator">=</span> None <span class="token punctuation">)</span> :
        pass


<span class="token comment"># Định nghĩa Interface TokenFallbackInterface</span>
<span class="token comment"># Hàm tokenFallback được gọi khi có 1 lượng token được gửi vào địa chỉ contract (tương tự như fallback function xử lý việc nhận ICX)</span>
class TokenFallbackInterface <span class="token punctuation">(</span> InterfaceScore <span class="token punctuation">)</span> :
    @interface
    def tokenFallback <span class="token punctuation">(</span> self, _from: Address, _value: int, _data: bytes <span class="token punctuation">)</span> :
        pass

<span class="token comment"># Implement</span>
class SampleToken <span class="token punctuation">(</span> IconScoreBase, TokenStandard <span class="token punctuation">)</span> :

    _BALANCES <span class="token operator">=</span> <span class="token string">'balances'</span>
    _TOTAL_SUPPLY <span class="token operator">=</span> <span class="token string">'total_supply'</span>
    _DECIMALS <span class="token operator">=</span> <span class="token string">'decimals'</span>
    
    <span class="token comment"># Event được emit khi hàm _transfer được gọi</span>
    @eventlog <span class="token punctuation">(</span> indexed <span class="token operator">=</span> <span class="token number">3</span> <span class="token punctuation">)</span>
    def Transfer <span class="token punctuation">(</span> self, _from: Address, _to: Address, _value: int, _data: bytes <span class="token punctuation">)</span> :
        pass
    
    <span class="token comment"># Định nghĩa các biến cần lưu trữ trong contract</span>
    <span class="token comment"># </span> <span class="token variable">`</span></span> _total_supply <span class="token variable"><span class="token variable">`</span> dạng int <span class="token punctuation">(</span> Tổng số token được tạo ra <span class="token punctuation">)</span>
    <span class="token comment"># </span> <span class="token variable">`</span></span> _decimals <span class="token variable"><span class="token variable">`</span> dạng int, dùng để tính toán ra <span class="token variable">`</span></span> _total_supply <span class="token variable"><span class="token variable">`</span>
    <span class="token comment"># </span> <span class="token variable">`</span></span> _balances <span class="token variable"><span class="token variable">`</span> dạng <span class="token punctuation">(</span> key <span class="token operator">=</span> <span class="token operator">&gt;</span> value <span class="token punctuation">)</span> lưu số dư token của các tài khoản
    def __init__ <span class="token punctuation">(</span> self, db: IconScoreDatabase <span class="token punctuation">)</span> - <span class="token operator">&gt;</span> None:
        super <span class="token punctuation">(</span> <span class="token punctuation">)</span> .__init__ <span class="token punctuation">(</span> db <span class="token punctuation">)</span>
        self._total_supply <span class="token operator">=</span> VarDB <span class="token punctuation">(</span> self._TOTAL_SUPPLY, db, <span class="token assign-left variable">value_type</span> <span class="token operator">=</span> int <span class="token punctuation">)</span>
        self._decimals <span class="token operator">=</span> VarDB <span class="token punctuation">(</span> self._DECIMALS, db, <span class="token assign-left variable">value_type</span> <span class="token operator">=</span> int <span class="token punctuation">)</span>
        self._balances <span class="token operator">=</span> DictDB <span class="token punctuation">(</span> self._BALANCES, db, <span class="token assign-left variable">value_type</span> <span class="token operator">=</span> int <span class="token punctuation">)</span>
    
    <span class="token comment"># Tính toán số lượng token phát hành</span>
    <span class="token comment"># Tất cả lượng token ban đầu được nắm giữ bởi địa chỉ deploy contract</span>
    def on_install <span class="token punctuation">(</span> self, _initialSupply: int, _decimals: int <span class="token punctuation">)</span> - <span class="token operator">&gt;</span> None:
        super <span class="token punctuation">(</span> <span class="token punctuation">)</span> .on_install <span class="token punctuation">(</span> <span class="token punctuation">)</span>

        <span class="token keyword">if</span> _initialSupply <span class="token operator">&lt;</span> <span class="token number">0</span> :
            revert <span class="token punctuation">(</span> <span class="token string">"Initial supply cannot be less than zero"</span> <span class="token punctuation">)</span>

        <span class="token keyword">if</span> _decimals <span class="token operator">&lt;</span> <span class="token number">0</span> :
            revert <span class="token punctuation">(</span> <span class="token string">"Decimals cannot be less than zero"</span> <span class="token punctuation">)</span>

        total_supply <span class="token operator">=</span> _initialSupply * <span class="token number">10</span> ** _decimals
        Logger.debug <span class="token punctuation">(</span> f <span class="token string">'on_install: total_supply={total_supply}'</span> , TAG <span class="token punctuation">)</span>

        self._total_supply.set <span class="token punctuation">(</span> total_supply <span class="token punctuation">)</span>
        self._decimals.set <span class="token punctuation">(</span> _decimals <span class="token punctuation">)</span>
        self._balances <span class="token punctuation">[</span> self.msg.sender <span class="token punctuation">]</span> <span class="token operator">=</span> total_supply

    def on_update <span class="token punctuation">(</span> self <span class="token punctuation">)</span> - <span class="token operator">&gt;</span> None:
        super <span class="token punctuation">(</span> <span class="token punctuation">)</span> .on_update <span class="token punctuation">(</span> <span class="token punctuation">)</span>
    
    <span class="token comment"># Tên của token</span>
    @external <span class="token punctuation">(</span> readonly <span class="token operator">=</span> True <span class="token punctuation">)</span>
    def name <span class="token punctuation">(</span> self <span class="token punctuation">)</span> - <span class="token operator">&gt;</span> str:
        <span class="token builtin class-name">return</span> <span class="token string">"SampleToken"</span>
    
    <span class="token comment"># Ký hiệu của token</span>
    @external <span class="token punctuation">(</span> readonly <span class="token operator">=</span> True <span class="token punctuation">)</span>
    def symbol <span class="token punctuation">(</span> self <span class="token punctuation">)</span> - <span class="token operator">&gt;</span> str:
        <span class="token builtin class-name">return</span> <span class="token string">"ST"</span>

    @external <span class="token punctuation">(</span> readonly <span class="token operator">=</span> True <span class="token punctuation">)</span>
    def decimals <span class="token punctuation">(</span> self <span class="token punctuation">)</span> - <span class="token operator">&gt;</span> int:
        <span class="token builtin class-name">return</span> self._decimals.get <span class="token punctuation">(</span> <span class="token punctuation">)</span>

    @external <span class="token punctuation">(</span> readonly <span class="token operator">=</span> True <span class="token punctuation">)</span>
    def totalSupply <span class="token punctuation">(</span> self <span class="token punctuation">)</span> - <span class="token operator">&gt;</span> int:
        <span class="token builtin class-name">return</span> self._total_supply.get <span class="token punctuation">(</span> <span class="token punctuation">)</span>
    
    <span class="token comment"># truy vấn số dư của địa chỉ</span>
    @external <span class="token punctuation">(</span> readonly <span class="token operator">=</span> True <span class="token punctuation">)</span>
    def balanceOf <span class="token punctuation">(</span> self, _owner: Address <span class="token punctuation">)</span> - <span class="token operator">&gt;</span> int:
        <span class="token builtin class-name">return</span> self._balances <span class="token punctuation">[</span> _owner <span class="token punctuation">]</span>

    @external
    def transfer <span class="token punctuation">(</span> self, _to: Address, _value: int, _data: bytes <span class="token operator">=</span> None <span class="token punctuation">)</span> :
        <span class="token keyword">if</span> _data is None:
            _data <span class="token operator">=</span> b <span class="token string">'None'</span>
        self._transfer <span class="token punctuation">(</span> self.msg.sender, _to, _value, _data <span class="token punctuation">)</span>
    
    <span class="token comment"># Chuyển tokne từ </span> <span class="token variable">`</span></span> _from <span class="token variable"><span class="token variable">`</span> sang <span class="token variable">`</span></span> _to <span class="token variable"><span class="token variable">`</span>
    def _transfer <span class="token punctuation">(</span> self, _from: Address, _to: Address, _value: int, _data: bytes <span class="token punctuation">)</span> :

        <span class="token comment"># Nếu giá trị âm hoặc địa chỉ gửi không đủ số dư thì giao dịch sẽ bị revert</span>
        <span class="token keyword">if</span> _value <span class="token operator">&lt;</span> <span class="token number">0</span> :
            revert <span class="token punctuation">(</span> <span class="token string">"Transferring value cannot be less than zero"</span> <span class="token punctuation">)</span>
        <span class="token keyword">if</span> self._balances <span class="token punctuation">[</span> _from <span class="token punctuation">]</span> <span class="token operator">&lt;</span> _value:
            revert <span class="token punctuation">(</span> <span class="token string">"Out of balance"</span> <span class="token punctuation">)</span>

        self._balances <span class="token punctuation">[</span> _from <span class="token punctuation">]</span> <span class="token operator">=</span> self._balances <span class="token punctuation">[</span> _from <span class="token punctuation">]</span> - _value
        self._balances <span class="token punctuation">[</span> _to <span class="token punctuation">]</span> <span class="token operator">=</span> self._balances <span class="token punctuation">[</span> _to <span class="token punctuation">]</span> + _value
        
          <span class="token comment"># Nếu địa chỉ đích là 1 contract thì sẽ gọi đến hàm tokenFallback</span>
        <span class="token keyword">if</span> _to.is_contract:
            recipient_score <span class="token operator">=</span> self.create_interface_score <span class="token punctuation">(</span> _to, TokenFallbackInterface <span class="token punctuation">)</span>
            recipient_score.tokenFallback <span class="token punctuation">(</span> _from, _value, _data <span class="token punctuation">)</span>

        <span class="token comment"># Emits an event log </span> <span class="token variable">`</span></span> Transfer`
        self.Transfer <span class="token punctuation">(</span> _from, _to, _value, _data <span class="token punctuation">)</span>
        Logger.debug <span class="token punctuation">(</span> f <span class="token string">'Transfer({_from}, {_to}, {_value}, {_data})'</span> , TAG <span class="token punctuation">)</span>

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tbears init sample-token SampleToken

` `

` ` ` py

# sample_token.py

from iconservice import *

TAG = 'SampleToken'

## Định nghĩa interface theo chuẩn IRC-2

class TokenStandard:

@abstractmethod

def name ( self ) - > str:

pass

@abstractmethod

def symbol ( self ) - > str:

pass

@abstractmethod

def decimals ( self ) - > int:

pass

@abstractmethod

def totalSupply ( self ) - > int:

pass

@abstractmethod

def balanceOf ( self, _owner: Address ) - > int:

pass

@abstractmethod

def transfer ( self, _to: Address, _value: int, _data: bytes = None ) :

pass

# Định nghĩa Interface TokenFallbackInterface

# Hàm tokenFallback được gọi khi có 1 lượng token được gửi vào địa chỉ contract (tương tự như fallback function xử lý việc nhận ICX)

class TokenFallbackInterface ( InterfaceScore ) :

@interface

def tokenFallback ( self, _from: Address, _value: int, _data: bytes ) :

pass

# Implement

class SampleToken ( IconScoreBase, TokenStandard ) :

_BALANCES = 'balances'

_TOTAL_SUPPLY = 'total_supply'

_DECIMALS = 'decimals'

# Event được emit khi hàm _transfer được gọi

@eventlog ( indexed = 3 )

def Transfer ( self, _from: Address, _to: Address, _value: int, _data: bytes ) :

pass

# Định nghĩa các biến cần lưu trữ trong contract

# ` _total_supply ` dạng int ( Tổng số token được tạo ra )

# ` _decimals ` dạng int, dùng để tính toán ra ` _total_supply `

# ` _balances ` dạng ( key = > value ) lưu số dư token của các tài khoản

def __init__ ( self, db: IconScoreDatabase ) - > None:

super ( ) .__init__ ( db )

self._total_supply = VarDB ( self._TOTAL_SUPPLY, db, value_type = int )

self._decimals = VarDB ( self._DECIMALS, db, value_type = int )

self._balances = DictDB ( self._BALANCES, db, value_type = int )

# Tính toán số lượng token phát hành

# Tất cả lượng token ban đầu được nắm giữ bởi địa chỉ deploy contract

def on_install ( self, _initialSupply: int, _decimals: int ) - > None:

super ( ) .on_install ( )

if _initialSupply < 0 :

revert ( "Initial supply cannot be less than zero" )

if _decimals < 0 :

revert ( "Decimals cannot be less than zero" )

total_supply = _initialSupply * 10 ** _decimals

Logger.debug ( f 'on_install: total_supply={total_supply}' , TAG )

self._total_supply.set ( total_supply )

self._decimals.set ( _decimals )

self._balances [ self.msg.sender ] = total_supply

def on_update ( self ) - > None:

super ( ) .on_update ( )

# Tên của token

@external ( readonly = True )

def name ( self ) - > str:

return "SampleToken"

# Ký hiệu của token

@external ( readonly = True )

def symbol ( self ) - > str:

return "ST"

@external ( readonly = True )

def decimals ( self ) - > int:

return self._decimals.get ( )

@external ( readonly = True )

def totalSupply ( self ) - > int:

return self._total_supply.get ( )

# truy vấn số dư của địa chỉ

@external ( readonly = True )

def balanceOf ( self, _owner: Address ) - > int:

return self._balances [ _owner ]

@external

def transfer ( self, _to: Address, _value: int, _data: bytes = None ) :

if _data is None:

_data = b 'None'

self._transfer ( self.msg.sender, _to, _value, _data )

# Chuyển tokne từ ` _from ` sang ` _to `

def _transfer ( self, _from: Address, _to: Address, _value: int, _data: bytes ) :

# Nếu giá trị âm hoặc địa chỉ gửi không đủ số dư thì giao dịch sẽ bị revert

if _value < 0 :

revert ( "Transferring value cannot be less than zero" )

if self._balances [ _from ] < _value:

revert ( "Out of balance" )

self._balances [ _from ] = self._balances [ _from ] - _value

self._balances [ _to ] = self._balances [ _to ] + _value

# Nếu địa chỉ đích là 1 contract thì sẽ gọi đến hàm tokenFallback

if _to.is_contract:

recipient_score = self.create_interface_score ( _to, TokenFallbackInterface )

recipient_score.tokenFallback ( _from, _value, _data )

# Emits an event log ` Transfer`

self.Transfer ( _from, _to, _value, _data )

Logger.debug ( f 'Transfer({_from}, {_to}, {_value}, {_data})' , TAG )

Deploy

Contract is finished, now let’s learn about deploying them to testnet Yeouido with tools tbears.

B1 : Create a deploy config file

deploy_hello.json

<span class="token punctuation">{</span>
  <span class="token property">"uri"</span> <span class="token operator">:</span> <span class="token string">"https://bicon.net.solidwallet.io/api/v3"</span> <span class="token punctuation">,</span>
  <span class="token property">"nid"</span> <span class="token operator">:</span> <span class="token string">"0x3"</span> <span class="token punctuation">,</span>
  <span class="token property">"keyStore"</span> <span class="token operator">:</span> <span class="token null keyword">null</span> <span class="token punctuation">,</span>
  <span class="token property">"from"</span> <span class="token operator">:</span> <span class="token string">"ĐỊA CHỈ CỦA BẠN"</span> <span class="token punctuation">,</span>
  <span class="token property">"to"</span> <span class="token operator">:</span> <span class="token string">"cx0000000000000000000000000000000000000000"</span> <span class="token punctuation">,</span>
  <span class="token property">"stepLimit"</span> <span class="token operator">:</span> <span class="token string">"0x5a000000"</span> <span class="token punctuation">,</span>
  <span class="token property">"deploy"</span> <span class="token operator">:</span> <span class="token punctuation">{</span>
    <span class="token property">"contentType"</span> <span class="token operator">:</span> <span class="token string">"tbears"</span> <span class="token punctuation">,</span>
    <span class="token property">"mode"</span> <span class="token operator">:</span> <span class="token string">"install"</span>
  <span class="token punctuation">}</span> <span class="token punctuation">,</span>
  <span class="token property">"txresult"</span> <span class="token operator">:</span> <span class="token punctuation">{</span> <span class="token punctuation">}</span> <span class="token punctuation">,</span>
  <span class="token property">"transfer"</span> <span class="token operator">:</span> <span class="token punctuation">{</span> <span class="token punctuation">}</span>
<span class="token punctuation">}</span>

{

"uri" : "https://bicon.net.solidwallet.io/api/v3" ,

"nid" : "0x3" ,

"keyStore" : null ,

"from" : "ĐỊA CHỈ CỦA BẠN" ,

"to" : "cx0000000000000000000000000000000000000000" ,

"stepLimit" : "0x5a000000" ,

"deploy" : {

"contentType" : "tbears" ,

"mode" : "install"

} ,

"txresult" : { } ,

"transfer" : { }

}

deploy_sample_token.json

<span class="token punctuation">{</span>
  <span class="token property">"uri"</span> <span class="token operator">:</span> <span class="token string">"https://bicon.net.solidwallet.io/api/v3"</span> <span class="token punctuation">,</span>
  <span class="token property">"nid"</span> <span class="token operator">:</span> <span class="token string">"0x3"</span> <span class="token punctuation">,</span>
  <span class="token property">"keyStore"</span> <span class="token operator">:</span> <span class="token null keyword">null</span> <span class="token punctuation">,</span>
  <span class="token property">"from"</span> <span class="token operator">:</span> <span class="token string">"ĐỊA CHỈ CỦA BẠN"</span> <span class="token punctuation">,</span>
  <span class="token property">"to"</span> <span class="token operator">:</span> <span class="token string">"cx0000000000000000000000000000000000000000"</span> <span class="token punctuation">,</span>
  <span class="token property">"stepLimit"</span> <span class="token operator">:</span> <span class="token string">"0x5a000000"</span> <span class="token punctuation">,</span>
  <span class="token property">"deploy"</span> <span class="token operator">:</span> <span class="token punctuation">{</span>
    <span class="token property">"contentType"</span> <span class="token operator">:</span> <span class="token string">"tbears"</span> <span class="token punctuation">,</span>
    <span class="token property">"mode"</span> <span class="token operator">:</span> <span class="token string">"install"</span> <span class="token punctuation">,</span>
    <span class="token property">"scoreParams"</span> <span class="token operator">:</span> <span class="token punctuation">{</span>
      <span class="token property">"_decimals"</span> <span class="token operator">:</span> <span class="token string">"0x12"</span> <span class="token punctuation">,</span>
      <span class="token property">"_initialSupply"</span> <span class="token operator">:</span> <span class="token string">"0x3e8"</span>
    <span class="token punctuation">}</span>
  <span class="token punctuation">}</span> <span class="token punctuation">,</span>
  <span class="token property">"txresult"</span> <span class="token operator">:</span> <span class="token punctuation">{</span> <span class="token punctuation">}</span> <span class="token punctuation">,</span>
  <span class="token property">"transfer"</span> <span class="token operator">:</span> <span class="token punctuation">{</span> <span class="token punctuation">}</span>
<span class="token punctuation">}</span>

{

"uri" : "https://bicon.net.solidwallet.io/api/v3" ,

"nid" : "0x3" ,

"keyStore" : null ,

"from" : "ĐỊA CHỈ CỦA BẠN" ,

"to" : "cx0000000000000000000000000000000000000000" ,

"stepLimit" : "0x5a000000" ,

"deploy" : {

"contentType" : "tbears" ,

"mode" : "install" ,

"scoreParams" : {

"_decimals" : "0x12" ,

"_initialSupply" : "0x3e8"

}

} ,

"transfer" : { }

}

Ham on_install in contract SampleToken need to pass two arguments to _decimals and _initialSupply to execute.

B2 : Create wallet

We install the ICONex extension (eg Metamask) to create an address on the ICON network. With Chrome browser, you can here

Click on the new wallet creation section, you will download the keystore file and change the extension to a json file, such as keystore.json .

B3 : Deploy to testnet with tbears

The current directory we have

/hello
/sample-token
deploy-hello.json
deploy_sample_token.json
keystore.json

/hello

/sample-token

deploy-hello.json

deploy_sample_token.json

keystore.json

Before deploying we need faucet ICX for the account on testnet at

tbears deploy hello -k keystore.json -c deploy-hello.json
tbears deploy sample-token -k keystore.json -c deploy-sample_token.json

tbears deploy hello -k keystore.json -c deploy-hello.json

tbears deploy sample-token -k keystore.json -c deploy-sample_token.json

Transaction hash will be returned after deploying, we can check whether the transaction was successful or not as well as the contract’s address on bicon.tracker.solidwallet.io page.

4. ICON SDK (Javascript SDK)

Each ICON node provides JSON-RPC APIs. To interact with an ICON node, we can either send raw JSON-RPC requests or use the ICON SDK in many different languages. ICON officially supports Java, Python, JavaScript and Swift. In the framework of the article, we will just learn about 1 type of SDK that is the Javascript SDK.

Setting

Javascript SDK is integrated in a node.js package, making it easy to install and use

Install via npm

<span class="token function">npm</span> <span class="token function">install</span> --save icon-sdk-js

1 2	<span class="token function">npm</span> <span class="token function">install</span> --save icon-sdk-js

Or CDN link

<span class="token operator">&lt;</span> script src <span class="token operator">=</span> <span class="token string">"https://cdn.jsdelivr.net/gh/icon-project/ <a class="__cf_email__" href="/cdn-cgi/l/email-protection">[email protected]</a> /build/icon-sdk-js.web.min.js"</span> <span class="token operator">&gt;</span> <span class="token operator">&lt;</span> <span class="token operator">/</span> script <span class="token operator">&gt;</span>

< script src = "https://cdn.jsdelivr.net/gh/icon-project/ <a class="__cf_email__" href="/cdn-cgi/l/email-protection">[email protected]</a> /build/icon-sdk-js.web.min.js" > < / script >

Using the SDK to interact with the deployed contract

Create an sdk directory and create an environment variable

mkdir sdk
cd sdk
touch .env

mkdir sdk

cd sdk

touch .env

<span class="token comment"># .env</span>
API_ENPOINT <span class="token operator">=</span> <span class="token string">'https://bicon.net.solidwallet.io/api/v3'</span>
PRIVATE_KEY <span class="token operator">=</span> <span class="token string">'PRIVATE KEY ĐỊA CHỈ CỦA BẠN'</span>
ADDRESS_CONTRACT_SAMPLE_TOKEN <span class="token operator">=</span> <span class="token string">'ĐỊA CHRI CONTRACT SAMPLE TOKEN ĐÃ DEPLOY'</span>
OWNER <span class="token operator">=</span> <span class="token string">'ĐỊA CHỈ DÙNG ĐỂ DEPLOY'</span>

# .env

API_ENPOINT = 'https://bicon.net.solidwallet.io/api/v3'

PRIVATE_KEY = 'PRIVATE KEY ĐỊA CHỈ CỦA BẠN'

ADDRESS_CONTRACT_SAMPLE_TOKEN = 'ĐỊA CHRI CONTRACT SAMPLE TOKEN ĐÃ DEPLOY'

OWNER = 'ĐỊA CHỈ DÙNG ĐỂ DEPLOY'

With the readonly functions, when called, there is no need to sign a transaction

<span class="token comment">// getBalance.js</span>
<span class="token keyword">const</span> IconService <span class="token operator">=</span> <span class="token function">require</span> <span class="token punctuation">(</span> <span class="token string">'icon-sdk-js'</span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>
<span class="token keyword">const</span> <span class="token punctuation">{</span> argv <span class="token punctuation">}</span> <span class="token operator">=</span> <span class="token function">require</span> <span class="token punctuation">(</span> <span class="token string">'yargs'</span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>
<span class="token function">require</span> <span class="token punctuation">(</span> <span class="token string">'dotenv'</span> <span class="token punctuation">)</span> <span class="token punctuation">.</span> <span class="token function">config</span> <span class="token punctuation">(</span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>
<span class="token keyword">const</span> <span class="token punctuation">{</span> HttpProvider <span class="token punctuation">,</span> IconBuilder <span class="token punctuation">}</span> <span class="token operator">=</span> IconService <span class="token punctuation">;</span>

<span class="token comment">// Kết nối đến mạng testnet</span>
<span class="token keyword">const</span> provider <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">HttpProvider</span> <span class="token punctuation">(</span> process <span class="token punctuation">.</span> env <span class="token punctuation">.</span> <span class="token constant">API_ENPOINT</span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>
<span class="token keyword">const</span> iconService <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">IconService</span> <span class="token punctuation">(</span> provider <span class="token punctuation">)</span> <span class="token punctuation">;</span>
<span class="token keyword">const</span> <span class="token punctuation">{</span> CallBuilder <span class="token punctuation">}</span> <span class="token operator">=</span> IconBuilder <span class="token punctuation">;</span>

<span class="token keyword">const</span> owner <span class="token operator">=</span> process <span class="token punctuation">.</span> env <span class="token punctuation">.</span> <span class="token constant">OWNER</span> <span class="token punctuation">;</span>
<span class="token keyword">const</span> instanceContract <span class="token operator">=</span> process <span class="token punctuation">.</span> env <span class="token punctuation">.</span> <span class="token constant">ADDRESS_CONTRACT_SAMPLE_TOKEN</span> <span class="token punctuation">;</span>
<span class="token keyword">let</span> account <span class="token operator">=</span> owner <span class="token punctuation">;</span>

<span class="token keyword">if</span> <span class="token punctuation">(</span> argv <span class="token punctuation">.</span> address <span class="token punctuation">)</span> <span class="token punctuation">{</span>
 account <span class="token operator">=</span> argv <span class="token punctuation">.</span> address <span class="token punctuation">;</span>
<span class="token punctuation">}</span>

<span class="token keyword">async</span> <span class="token keyword">function</span> <span class="token function">getBalance</span> <span class="token punctuation">(</span> <span class="token punctuation">)</span> <span class="token punctuation">{</span>
 <span class="token keyword">try</span> <span class="token punctuation">{</span>
    <span class="token comment">// class CallBuilder dùng để build thành các transaction object chuyên gọi các hàm read-only</span>
    <span class="token comment">// https://link.sun-asterisk.vn/FPM4jf </span>
   <span class="token keyword">const</span> txObj <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">CallBuilder</span> <span class="token punctuation">(</span> <span class="token punctuation">)</span>
     <span class="token punctuation">.</span> <span class="token function">from</span> <span class="token punctuation">(</span> owner <span class="token punctuation">)</span>
     <span class="token punctuation">.</span> <span class="token function">to</span> <span class="token punctuation">(</span> instanceContract <span class="token punctuation">)</span>
     <span class="token punctuation">.</span> <span class="token function">method</span> <span class="token punctuation">(</span> <span class="token string">'balanceOf'</span> <span class="token punctuation">)</span>
     <span class="token punctuation">.</span> <span class="token function">params</span> <span class="token punctuation">(</span> <span class="token punctuation">{</span>
       _owner <span class="token operator">:</span> account <span class="token punctuation">,</span>
     <span class="token punctuation">}</span> <span class="token punctuation">)</span>
     <span class="token punctuation">.</span> <span class="token function">build</span> <span class="token punctuation">(</span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>

   <span class="token keyword">let</span> balance <span class="token operator">=</span> <span class="token keyword">await</span> <span class="token function">iconService</span> <span class="token punctuation">.</span> <span class="token function">call</span> <span class="token punctuation">(</span> txObj <span class="token punctuation">)</span> <span class="token punctuation">.</span> <span class="token function">execute</span> <span class="token punctuation">(</span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>
   balance <span class="token operator">=</span> <span class="token function">parseInt</span> <span class="token punctuation">(</span> balance <span class="token punctuation">)</span> <span class="token punctuation">;</span>
   console <span class="token punctuation">.</span> <span class="token function">log</span> <span class="token punctuation">(</span> <span class="token punctuation">{</span> balance <span class="token punctuation">}</span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>
   <span class="token keyword">return</span> balance <span class="token punctuation">;</span>
 <span class="token punctuation">}</span> <span class="token keyword">catch</span> <span class="token punctuation">(</span> err <span class="token punctuation">)</span> <span class="token punctuation">{</span>
   console <span class="token punctuation">.</span> <span class="token function">log</span> <span class="token punctuation">(</span> <span class="token punctuation">{</span> err <span class="token punctuation">}</span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>
 <span class="token punctuation">}</span>
<span class="token punctuation">}</span>

<span class="token function">getBalance</span> <span class="token punctuation">(</span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>

// getBalance.js

const IconService = require ( 'icon-sdk-js' ) ;

const { argv } = require ( 'yargs' ) ;

require ( 'dotenv' ) . config ( ) ;

const { HttpProvider , IconBuilder } = IconService ;

// Kết nối đến mạng testnet

const provider = new HttpProvider ( process . env . API_ENPOINT ) ;

const iconService = new IconService ( provider ) ;

const { CallBuilder } = IconBuilder ;

const owner = process . env . OWNER ;

const instanceContract = process . env . ADDRESS_CONTRACT_SAMPLE_TOKEN ;

let account = owner ;

if ( argv . address ) {

account = argv . address ;

}

async function getBalance ( ) {

try {

// class CallBuilder dùng để build thành các transaction object chuyên gọi các hàm read-only

// https://link.sun-asterisk.vn/FPM4jf

const txObj = new CallBuilder ( )

. from ( owner )

. to ( instanceContract )

. method ( 'balanceOf' )

. params ( {

_owner : account ,

} )

. build ( ) ;

let balance = await iconService . call ( txObj ) . execute ( ) ;

balance = parseInt ( balance ) ;

console . log ( { balance } ) ;

return balance ;

} catch ( err ) {

console . log ( { err } ) ;

}

getBalance ( ) ;

For other functions, when we call through the SDK we need to do the signing

<span class="token comment">// transfer.js</span>
<span class="token keyword">const</span> IconService <span class="token operator">=</span> <span class="token function">require</span> <span class="token punctuation">(</span> <span class="token string">'icon-sdk-js'</span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>
<span class="token keyword">const</span> <span class="token punctuation">{</span> argv <span class="token punctuation">}</span> <span class="token operator">=</span> <span class="token function">require</span> <span class="token punctuation">(</span> <span class="token string">'yargs'</span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>
<span class="token function">require</span> <span class="token punctuation">(</span> <span class="token string">'dotenv'</span> <span class="token punctuation">)</span> <span class="token punctuation">.</span> <span class="token function">config</span> <span class="token punctuation">(</span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>
<span class="token keyword">const</span> <span class="token punctuation">{</span> IconWallet <span class="token punctuation">,</span> HttpProvider <span class="token punctuation">,</span> SignedTransaction <span class="token punctuation">,</span> IconBuilder <span class="token punctuation">,</span> IconConverter <span class="token punctuation">}</span> <span class="token operator">=</span> IconService <span class="token punctuation">;</span>
<span class="token keyword">const</span> provider <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">HttpProvider</span> <span class="token punctuation">(</span> process <span class="token punctuation">.</span> env <span class="token punctuation">.</span> <span class="token constant">API_ENPOINT</span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>
<span class="token keyword">const</span> iconService <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">IconService</span> <span class="token punctuation">(</span> provider <span class="token punctuation">)</span> <span class="token punctuation">;</span>
<span class="token keyword">const</span> <span class="token punctuation">{</span> CallTransactionBuilder <span class="token punctuation">}</span> <span class="token operator">=</span> IconBuilder <span class="token punctuation">;</span>

<span class="token comment">// Import private key cảu account vào wallet, dùng cho việc ký giao dịch</span>
<span class="token keyword">const</span> wallet <span class="token operator">=</span> IconWallet <span class="token punctuation">.</span> <span class="token function">loadPrivateKey</span> <span class="token punctuation">(</span> process <span class="token punctuation">.</span> env <span class="token punctuation">.</span> <span class="token constant">PRIVATE_KEY</span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>
<span class="token keyword">const</span> owner <span class="token operator">=</span> process <span class="token punctuation">.</span> env <span class="token punctuation">.</span> <span class="token constant">OWNER</span> <span class="token punctuation">;</span>
<span class="token keyword">const</span> instanceContract <span class="token operator">=</span> process <span class="token punctuation">.</span> env <span class="token punctuation">.</span> <span class="token constant">ADDRESS_CONTRACT_SAMPLE_TOKEN</span> <span class="token punctuation">;</span>
<span class="token keyword">const</span> to <span class="token operator">=</span> argv <span class="token punctuation">.</span> to <span class="token punctuation">;</span>
<span class="token keyword">const</span> value <span class="token operator">=</span> <span class="token function">parseInt</span> <span class="token punctuation">(</span> argv <span class="token punctuation">.</span> value <span class="token punctuation">)</span> <span class="token punctuation">;</span>

<span class="token keyword">async</span> <span class="token keyword">function</span> <span class="token function">transfer</span> <span class="token punctuation">(</span> <span class="token punctuation">)</span> <span class="token punctuation">{</span>
 <span class="token keyword">try</span> <span class="token punctuation">{</span>
 <span class="token comment">// Class CallTransactionBuilder dùng để build các giao dịch gọi đến các hàm thay đổi trạng thái của blockchain</span>
 <span class="token comment">// Hàm transfer nhận vào 2 params là `_to` và `_value`</span>
   <span class="token keyword">const</span> txObj <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">CallTransactionBuilder</span> <span class="token punctuation">(</span> <span class="token punctuation">)</span>
     <span class="token punctuation">.</span> <span class="token function">from</span> <span class="token punctuation">(</span> owner <span class="token punctuation">)</span>
     <span class="token punctuation">.</span> <span class="token function">to</span> <span class="token punctuation">(</span> instanceContract <span class="token punctuation">)</span>
     <span class="token punctuation">.</span> <span class="token function">stepLimit</span> <span class="token punctuation">(</span> IconConverter <span class="token punctuation">.</span> <span class="token function">toBigNumber</span> <span class="token punctuation">(</span> <span class="token string">'2000000'</span> <span class="token punctuation">)</span> <span class="token punctuation">)</span>
     <span class="token punctuation">.</span> <span class="token function">nid</span> <span class="token punctuation">(</span> IconConverter <span class="token punctuation">.</span> <span class="token function">toBigNumber</span> <span class="token punctuation">(</span> <span class="token string">'3'</span> <span class="token punctuation">)</span> <span class="token punctuation">)</span>
     <span class="token punctuation">.</span> <span class="token function">nonce</span> <span class="token punctuation">(</span> IconConverter <span class="token punctuation">.</span> <span class="token function">toBigNumber</span> <span class="token punctuation">(</span> <span class="token string">'1'</span> <span class="token punctuation">)</span> <span class="token punctuation">)</span>
     <span class="token punctuation">.</span> <span class="token function">version</span> <span class="token punctuation">(</span> IconConverter <span class="token punctuation">.</span> <span class="token function">toBigNumber</span> <span class="token punctuation">(</span> <span class="token string">'3'</span> <span class="token punctuation">)</span> <span class="token punctuation">)</span>
     <span class="token punctuation">.</span> <span class="token function">timestamp</span> <span class="token punctuation">(</span> <span class="token keyword">new</span> <span class="token class-name">Date</span> <span class="token punctuation">(</span> <span class="token punctuation">)</span> <span class="token punctuation">.</span> <span class="token function">getTime</span> <span class="token punctuation">(</span> <span class="token punctuation">)</span> <span class="token operator">*</span> <span class="token number">1000</span> <span class="token punctuation">)</span>
     <span class="token punctuation">.</span> <span class="token function">method</span> <span class="token punctuation">(</span> <span class="token string">'transfer'</span> <span class="token punctuation">)</span>
     <span class="token punctuation">.</span> <span class="token function">params</span> <span class="token punctuation">(</span> <span class="token punctuation">{</span>
       _to <span class="token operator">:</span> to <span class="token punctuation">,</span>
       _value <span class="token operator">:</span> IconConverter <span class="token punctuation">.</span> <span class="token function">toHex</span> <span class="token punctuation">(</span> value <span class="token punctuation">)</span> <span class="token punctuation">,</span>
     <span class="token punctuation">}</span> <span class="token punctuation">)</span>
     <span class="token punctuation">.</span> <span class="token function">build</span> <span class="token punctuation">(</span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>

   <span class="token keyword">const</span> signedTransaction <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">SignedTransaction</span> <span class="token punctuation">(</span> txObj <span class="token punctuation">,</span> wallet <span class="token punctuation">)</span> <span class="token punctuation">;</span>
   <span class="token keyword">const</span> txHash <span class="token operator">=</span> <span class="token keyword">await</span> iconService <span class="token punctuation">.</span> <span class="token function">sendTransaction</span> <span class="token punctuation">(</span> signedTransaction <span class="token punctuation">)</span> <span class="token punctuation">.</span> <span class="token function">execute</span> <span class="token punctuation">(</span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>

   console <span class="token punctuation">.</span> <span class="token function">log</span> <span class="token punctuation">(</span> <span class="token punctuation">{</span> txHash <span class="token punctuation">}</span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>
 <span class="token punctuation">}</span> <span class="token keyword">catch</span> <span class="token punctuation">(</span> err <span class="token punctuation">)</span> <span class="token punctuation">{</span>
   console <span class="token punctuation">.</span> <span class="token function">log</span> <span class="token punctuation">(</span> <span class="token punctuation">{</span> err <span class="token punctuation">}</span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>
 <span class="token punctuation">}</span>
<span class="token punctuation">}</span>

<span class="token function">transfer</span> <span class="token punctuation">(</span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>

// transfer.js

const { IconWallet , HttpProvider , SignedTransaction , IconBuilder , IconConverter } = IconService ;

const { CallTransactionBuilder } = IconBuilder ;

// Import private key cảu account vào wallet, dùng cho việc ký giao dịch

const wallet = IconWallet . loadPrivateKey ( process . env . PRIVATE_KEY ) ;

const to = argv . to ;

const value = parseInt ( argv . value ) ;

async function transfer ( ) {

try {

// Class CallTransactionBuilder dùng để build các giao dịch gọi đến các hàm thay đổi trạng thái của blockchain

// Hàm transfer nhận vào 2 params là `_to` và `_value`

const txObj = new CallTransactionBuilder ( )

. from ( owner )

. to ( instanceContract )

. stepLimit ( IconConverter . toBigNumber ( '2000000' ) )

. nid ( IconConverter . toBigNumber ( '3' ) )

. nonce ( IconConverter . toBigNumber ( '1' ) )

. version ( IconConverter . toBigNumber ( '3' ) )

. timestamp ( new Date ( ) . getTime ( ) * 1000 )

. method ( 'transfer' )

. params ( {

_to : to ,

_value : IconConverter . toHex ( value ) ,

} )

const signedTransaction = new SignedTransaction ( txObj , wallet ) ;

const txHash = await iconService . sendTransaction ( signedTransaction ) . execute ( ) ;

console . log ( { txHash } ) ;

console . log ( { err } ) ;

}

transfer ( ) ;

Run:

node getBalance --address <span class="token operator">=</span> <span class="token operator">&lt;</span> tài khoản bạn cần truy vấn số dư token <span class="token operator">&gt;</span>
node transfer --to <span class="token operator">=</span> <span class="token operator">&lt;</span> địa chỉ nhận token <span class="token operator">&gt;</span> --value <span class="token operator">=</span>

node getBalance --address = < tài khoản bạn cần truy vấn số dư token >

node transfer --to = < địa chỉ nhận token > --value =

Note : To learn the functions of the modules in the Javascript SDK, you can refer to Github above.

References

ICON Documentation

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Source : Viblo

ICON – TCP / IP of Blockchain platform?

1. Introduction

2. Some basic concepts

Account

Deal

Transaction fee

Formula for calculating step

Policy support transaction fees for users

Virtual Step

ICON nodes

3. Write smart contract

Hello world

Implement Token

Deploy

4. ICON SDK (Javascript SDK)

Setting

Using the SDK to interact with the deployed contract

With the readonly functions, when called, there is no need to sign a transaction

For other functions, when we call through the SDK we need to do the signing

References

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