恒星网络stellar代币小试

看到恒星的blog说也可以做1CO，想对比一下和ETH的区别，毕竟恒星STR/XLM近期可以说非常强势，不知不觉市值到了第6。
先了解了一下开发文档https://www.stellar.org/developers/，简要总结以下几点

1. 同以太坊一样，需要一个RPC服务器，以太坊节点可以提供rpc服务，STR是用一个叫Horizon API Server的东西，可以自建，也可以用官方或第三方公开的
2. STR地址也是免费生成的，但是激活需要5个恒星币，每次上链操作需要1/100000(10万分之一)个恒星币
3. 自定义的资产设置好信任线之后，是可以自由交换的，比如我发了资产A，其他人发了资产B，可以在恒星内部自由交换

废话不说，上代码操作(环境py3.6)

生成2个地址，

一个用于资产发布，一个用户资产接收，辅助函数如下

from stellar_base.keypair import Keypair
import requests
from stellar_base.asset import Asset
from stellar_base.horizon import horizon_testnet
from stellar_base.operation  import ChangeTrust,Payment
from stellar_base.memo import TextMemo
from stellar_base.transaction import Transaction
from stellar_base.transaction_envelope import TransactionEnvelope as Te
horizon = horizon_testnet()

def create_account():
    '''
    ' 账号也就是随机生成的地址和私钥
    '''
    kp = Keypair.random()
    publickey = kp.address().decode()
    seed = kp.seed().decode()
    return publickey, seed

def active_account(address):
    '''
    ' 测试网络中，可以找机器人要测试币，激活账号
    '''
    requests.get('https://horizon-testnet.stellar.org/friendbot?addr=' + address)
    
def test_accounts(address):
    resp=horizon.account(address)  
    if 'balances' in resp:
        print(json.dumps(resp['balances'],indent=1))     #账号状态正常
    else:
        print(resp['detail'])       #账号状态异常

测试结果如下,每个账号发了10000测试币

>>> address, password = create_account()
>>> active_account(address)
test_accounts(address)
>>> test_accounts(address)
[{'balance': '10000.0000000', 'buying_liabilities': '0.0000000', 'selling_liabilities': '0.0000000', 'asset_type': 'native'}]
>>> customer_address, customer_password = create_account()
>>> active_account(customer_address)
test_accounts(customer_address)
>>> test_accounts(customer_address)
[{'balance': '10000.0000000', 'buying_liabilities': '0.0000000', 'selling_liabilities': '0.0000000', 'asset_type': 'native'}]

账号1作为发行资产方，账号2作为接收方

辅助函数如下

def create_asset(code,issuer_address):
    return Asset(code, issuer_address)

def change_trust(asset,receiver_address):
    op = ChangeTrust({
        'source': receiver_address,
        'asset': asset,
        'limit': '5000'
    })
    
    sequence = horizon.account(customer_address).get('sequence')
    msg = TextMemo('Change Trust Operation')
    
    tx = Transaction(
        source=customer_address,
        opts={
            'sequence': sequence,
            'memo': msg,
            'operations': [
                op,
            ],
        },
    )
    
    receiving_account = Keypair.from_seed(customer_password)
    envelope = Te(tx=tx, opts={"network_id": "TESTNET"})
    envelope.sign(receiving_account)
    
    xdr_envelope = envelope.xdr()
    response = horizon.submit(xdr_envelope)
    if 'result_xdr' in response:
        print('Successful')
    else:
        print('Things go Fishy')

测试结果

>>> asset = create_asset("TEST1",address)
>>> change_trust(asset,customer_address)
Successful
>>> test_accounts(customer_address)  
[
 {
  "balance": "0.0000000",
  "limit": "5000.0000000",
  "buying_liabilities": "0.0000000",
  "selling_liabilities": "0.0000000",
  "asset_type": "credit_alphanum12",
  "asset_code": "TEST1",
  "asset_issuer": "GC4AO3UUFPPCJTEKUKEZEUVIB6QBUXSGDRBZJJIDSD3QFN2MJJ7V4ACS"
 },
 {
  "balance": "9999.9999900",
  "buying_liabilities": "0.0000000",
  "selling_liabilities": "0.0000000",
  "asset_type": "native"
 }
]

可以看到，customer_address添加了一条对TEST1的信任线，上限5000,但是还没有实际的余额

将TEST1资产转移到custoner_address

辅助函数如下

def transfer_fund(amount,asset,customer_address,issue_address,issuer_seed):
    print('Transferring fund to {}'.format(customer_address))
    
    op = Payment({
        'source': issue_address,
        'destination': customer_address,
        'asset': asset,
        'amount': str(amount)
    })
    
    msg = TextMemo('Test Payment')
    sequence = horizon.account(issue_address).get('sequence')
    
    tx = Transaction(
        source=issue_address,
        opts={
            'sequence': sequence,
            'memo': msg,
            'operations': [
                op,
            ],
        },
    )
    
    issuer_account = Keypair.from_seed(issuer_seed)
    envelope = Te(tx=tx, opts={"network_id": "TESTNET"})
    envelope.sign(issuer_account)
    xdr_envelope = envelope.xdr()
    
    response = horizon.submit(xdr_envelope)
    
    if 'result_xdr' in response:
        print('Successful Transfer')
    else:
        print('Things go Fishy')

运行结果如下

Transferring fund to GDJZY3YQB4E3KXHTHT5KVS2PZPJVGGVUJ6KJQ6F7NEE7INQLL4EMX5QF
Successful Transfer
>>> test_accounts(customer_address)   
[
 {
  "balance": "1000.0000000",
  "limit": "5000.0000000",
  "buying_liabilities": "0.0000000",
  "selling_liabilities": "0.0000000",
  "asset_type": "credit_alphanum12",
  "asset_code": "TEST1",
  "asset_issuer": "GC4AO3UUFPPCJTEKUKEZEUVIB6QBUXSGDRBZJJIDSD3QFN2MJJ7V4ACS"
 },
 {
  "balance": "9999.9999900",
  "buying_liabilities": "0.0000000",
  "selling_liabilities": "0.0000000",
  "asset_type": "native"
 }
]

可以看到，customer现在有1000个TEST1资产了，limit是最大持有量，如果超过了5000个，是会不成功的

后面再来个小结吧

1. 转账非常快，几乎可以在s级完成
2. 这个资产和ETH的ERC20还有点不太一样，有点像借贷关系，示例中是没有总量限定的，也就是可以给任意多个customer_address发送资产，只要不操过信任基线中设置的limit就行，限定总量类型的还要再研究一下资产的文档