异步请求¶
现在我们支持通过异步请求来提交事务了,当然我们不会强迫你使用异步,毕竟同步代码更容易编写,也有着更多的开发库可以选择。
Server
有一个参数是 client,在这里我们有必要提及一下它,如果你不明确的设置这个参数,
那么 SDK 将默认使用 RequestsClient
的实例,它是一个同步的客户端;
当然,你也可以指定一个异步的 HTTP 客户端,例如: AiohttpClient
。
如果你设置了一个异步的客户端,那么所有的请求都是异步的,反之则是同步的。
下面这个示例演示了如何通过异步请求发起一笔付款,你可以与 这个示例 进行对比, 它们的功能是完全相同的,只是后者发起的是同步请求。
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 | """
The effect of this example is the same as `payment.py`, but this example is asynchronous.
Create, sign, and submit a transaction using Python Stellar SDK.
Assumes that you have the following items:
1. Secret key of a funded account to be the source account
2. Public key of an existing account as a recipient
These two keys can be created and funded by the friendbot at
https://www.stellar.org/laboratory/ under the heading "Quick Start: Test Account"
3. Access to Python Stellar SDK (https://github.com/StellarCN/py-stellar-base) through Python shell.
"""
import asyncio
from stellar_sdk import Server, Keypair, TransactionBuilder, Network, AiohttpClient
# The source account is the account we will be signing and sending from.
source_secret_key = "SBFZCHU5645DOKRWYBXVOXY2ELGJKFRX6VGGPRYUWHQ7PMXXJNDZFMKD"
# Derive Keypair object and public key (that starts with a G) from the secret
source_keypair = Keypair.from_secret(source_secret_key)
source_public_key = source_keypair.public_key
receiver_public_key = "GA7YNBW5CBTJZ3ZZOWX3ZNBKD6OE7A7IHUQVWMY62W2ZBG2SGZVOOPVH"
async def main():
# Configure StellarSdk to talk to the horizon instance hosted by Stellar.org
# To use the live network, set the hostname to 'horizon.stellar.org'
# When we use the `with` syntax, it automatically releases the resources it occupies.
async with Server(
horizon_url="https://horizon-testnet.stellar.org", client=AiohttpClient()
) as server:
# Transactions require a valid sequence number that is specific to this account.
# We can fetch the current sequence number for the source account from Horizon.
source_account = await server.load_account(source_public_key)
base_fee = await server.fetch_base_fee()
# we are going to submit the transaction to the test network,
# so network_passphrase is `Network.TESTNET_NETWORK_PASSPHRASE`,
# if you want to submit to the public network, please use `Network.PUBLIC_NETWORK_PASSPHRASE`.
transaction = (
TransactionBuilder(
source_account=source_account,
network_passphrase=Network.TESTNET_NETWORK_PASSPHRASE,
base_fee=base_fee,
)
.add_text_memo("Hello, Stellar!") # Add a memo
# Add a payment operation to the transaction
# Send 350.1234567 XLM to receiver
# Specify 350.1234567 lumens. Lumens are divisible to seven digits past the decimal.
.append_payment_op(receiver_public_key, "350.1234567", "XLM")
.set_timeout(30) # Make this transaction valid for the next 30 seconds only
.build()
)
# Sign this transaction with the secret key
# NOTE: signing is transaction is network specific. Test network transactions
# won't work in the public network. To switch networks, use the Network object
# as explained above (look for stellar_sdk.network.Network).
transaction.sign(source_keypair)
# Let's see the XDR (encoded in base64) of the transaction we just built
print(transaction.to_xdr())
# Submit the transaction to the Horizon server.
# The Horizon server will then submit the transaction into the network for us.
response = await server.submit_transaction(transaction)
print(response)
if __name__ == "__main__":
loop = asyncio.get_event_loop()
loop.run_until_complete(main())
loop.close()
# asyncio.run(main()) # Python 3.7+
|
下面这个示例演示了如何通过异步的监听多个端点。
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 | import asyncio
from stellar_sdk import AiohttpClient, Server
HORIZON_URL = "https://horizon.stellar.org"
async def payments():
async with Server(HORIZON_URL, AiohttpClient()) as server:
async for payment in server.payments().cursor(cursor="now").stream():
print(f"Payment: {payment}")
async def effects():
async with Server(HORIZON_URL, AiohttpClient()) as server:
async for effect in server.effects().cursor(cursor="now").stream():
print(f"Effect: {effect}")
async def operations():
async with Server(HORIZON_URL, AiohttpClient()) as server:
async for operation in server.operations().cursor(cursor="now").stream():
print(f"Operation: {operation}")
async def transactions():
async with Server(HORIZON_URL, AiohttpClient()) as server:
async for transaction in server.transactions().cursor(cursor="now").stream():
print(f"Transaction: {transaction}")
async def listen():
await asyncio.gather(
payments(),
effects(),
operations(),
transactions()
)
if __name__ == '__main__':
asyncio.run(listen())
|