Libra从入门到精通或放弃

Zeal

发布于 2020-11-11 15:18:46

5180

发布于 2020-11-11 15:18:46

文章被收录于专栏：Hyperledger实践Hyperledger实践

Facebook的Libra出来有一阵子, 追捧的有, 看衰的有,观望的有。笔者的观点是做总比不做好，数字货币也是社会发展的需要，官媒不也渐渐放出”数字人民币”的消息，天枰座的童虎还是不能小看的。

1. Libra是什么, 它的使命是什么?

Libra是全球最大的社交媒体facebook开发的数字货币，它的使命是建立一套简单的全球货币和金融基础设施，为数十亿人服务。

目标远大,但人家有底气啊, 二十多亿的用户，剩下就应该是监管和利益分配的问题了。

中文白皮书都准备了，文案写得还蛮好的，自行补脑。https://libra.org/zh-CN/white-paper/

2. Libra是怎么运营和管理的? Facebook一家独大?

Libra三部分组成:

它建立在安全、可扩展和可靠的区块链基础上;

它以赋予其内在价值的资产储备为后盾;

它由独立的Libra协会治理，该协会的任务是促进此金融生态系统的发展。

我们来看看站台的一些协会成员

Mastercard, visa, paypal, uber各行各业都有，计划是2020年协会创始人达到100。

有没中国玩家? 必须的，这两天, “火星财经与CSDN宣布联手发起Libra超级节点竞选” 。我觉得CSDN是想钱想疯了, gitchat也是搞钱, 可惜流量不好, 不然我也去赚点买菜钱。

天枰座的百龙霸打过来了，央行，银联，微信，支付宝和第三方支付等，后面应该会有动作，不是有一些国家想用人民币结算，虽然不多，但是数字货币基础设施总是要有的，不过会保守些，自然也是可监管，自主可控的，毕竟这里面的水很深，我们看看热闹就好。

3. 聊聊技术, 官方的入门例子, my first transaction

(1)下载和构建libra核心库

git clone https://github.com/libra/libra.git

cd libra

git checkout testnet

./scripts/dev_setup.sh

看到装了rust心里有点纳闷，笔者很早学过rust的语法, 看了几天就给borrow checker打败了，但貌似rust蛮受外国开发者喜爱, fuchsia底层和一些区块链和数字钱包等实现也慢青睐rust, 或者真是在代码质量和内存泄漏方面有更好的保证吧。

(2) 构建libra cli客户端，连接到Testnet

./scripts/cli/start_cli_testnet.sh

这里注意cmake版本必须是3以上, 否则会报一些路径不存在的错误，笔者的centos yum默认装了2的版本, yum有cmake3但好像用不了, 可能要软链接为cmake, 笔者是手工编译最新的cmake。

最后链接的时候如果发现error: linking with `cc` failed: exit code: 1

通常是机器的内存不够，这些问题在libra社区都能有人碰到过，还不少国人。。

链接测试的libra节点之后应该有这样的一个控制台:

Connected to validator at: ac.testnet.libra.org:8000

usage: <command> <args>

Use the following commands:

account | a

Account operations

query | q

Query operations

transfer | transferb | t | tb

<sender_account_address>|<sender_account_ref_id> <receiver_account_address>|<receiver_account_ref_id> <number_of_coins> [gas_unit_price_in_micro_libras (default=0)] [max_gas_amount_in_micro_libras (default 100000)] Suffix 'b' is for blocking.

Transfer coins (in libra) from account to another.

help | h

Prints this help

quit | q!

Exit this client

Please, input commands:

libra%

(3) 创建账号

创建两个账号, 并列出来, 应该是相当于有个电子钱包了，长长的ID就是账号的ID了,#0是账号1, #1是账号2, 是账号下标

libra% account create

>> Creating/retrieving next account from wallet

Created/retrieved account #0 address 6d7767d1f85d6d42bb18fcea71dcb89c433d98f7779c993d25205c4b7098c608

libra% account create

>> Creating/retrieving next account from wallet

Created/retrieved account #1 address 5ce81c0cd430659fe7dcad87836a13fbff1abd77c26eb4e85b561156a2ca0543

libra% account list

User account index: 0, address: 6d7767d1f85d6d42bb18fcea71dcb89c433d98f7779c993d25205c4b7098c608, sequence number: 0, status: Local

User account index: 1, address: 5ce81c0cd430659fe7dcad87836a13fbff1abd77c26eb4e85b561156a2ca0543, sequence number: 0, status: Local

增加LBR货币到账号, 0是账号下标, 110是增加的货币数值.

libra% account mint 0 110

>> Minting coins

Mint request submitted

账号2增加52个LBR

libra% account mint 1 52

>> Minting coins

Mint request submitted

查询账户余额

libra% query balance 0

Balance is: 110.000000

libra% query balance 1

Balance is: 52.000000

(4) 提起交易

查询账号交易序列号

libra% query sequence 0

>> Getting current sequence number

Sequence number is: 0

libra% query sequence 1

>> Getting current sequence number

Sequence number is: 0

转账

libra% transfer 0 1 10

>> Transferring

Transaction submitted to validator

To query for transaction status, run: query txn_acc_seq 0 0 <fetch_events=true|false>

从账号1转账给账号2, 转账金额为10个LBR

这是一个异步的交易，可以按照提示查询交易的状态和结果

libra% query txn_acc_seq 0 0 true

>> Getting committed transaction by account and sequence number

Committed transaction: SignedTransaction {

raw_txn: RawTransaction {

sender: 6d7767d1f85d6d42bb18fcea71dcb89c433d98f7779c993d25205c4b7098c608,

sequence_number: 0,

payload: {,

transaction: peer_to_peer_transaction,

args: [

{ADDRESS: 5ce81c0cd430659fe7dcad87836a13fbff1abd77c26eb4e85b561156a2ca0543},

{U64: 10000000},

]

max_gas_amount: 100000,

gas_unit_price: 0,

expiration_time: 1566474041s,

public_key: Ed25519PublicKey(

PublicKey(CompressedEdwardsY: [15, 1, 46, 78, 137, 132, 53, 170, 38, 34, 128, 144, 239, 224, 147, 45, 134, 121, 54, 246, 18, 148, 49, 23, 149, 59, 107, 163, 117, 227, 86, 113]), EdwardsPoint{

X: FieldElement51([332936837460180, 1776699723642978, 1606759207621664, 84590882227320, 44106645692162]),

Y: FieldElement51([1553100140577039, 1673525488571718, 239582280306563, 1630075796195707, 1993887956219571]),

Z: FieldElement51([1, 0, 0, 0, 0]),

T: FieldElement51([1821266226982014, 1734000264833885, 270163309747504, 275455197065552, 1853637604830383])

}),

signature: Ed25519Signature(

Signature( R: CompressedEdwardsY: [220, 241, 175, 100, 238, 181, 30, 10, 252, 197, 249, 188, 143, 91, 254, 1, 0, 85, 74, 134, 77, 151, 127, 83, 31, 21, 141, 245, 68, 52, 86, 191], s: Scalar{

bytes: [100, 59, 214, 44, 139, 144, 234, 0, 179, 135, 106, 206, 52, 58, 175, 109, 166, 26, 91, 169, 121, 132, 246, 189, 156, 118, 191, 156, 197, 235, 63, 12],

} ),

}

Events:

ContractEvent { access_path: AccessPath { address: 6d7767d1f85d6d42bb18fcea71dcb89c433d98f7779c993d25205c4b7098c608, type: Resource, hash: "217da6c6b3e19f1825cfb2676daecce3bf3de03cf26647c78df00b371b25cc97", suffix: "/sent_events_count/" } , index: 0, event_data: AccountEvent { account: 5ce81c0cd430659fe7dcad87836a13fbff1abd77c26eb4e85b561156a2ca0543, amount: 10000000 } }

ContractEvent { access_path: AccessPath { address: 5ce81c0cd430659fe7dcad87836a13fbff1abd77c26eb4e85b561156a2ca0543, type: Resource, hash: "217da6c6b3e19f1825cfb2676daecce3bf3de03cf26647c78df00b371b25cc97", suffix: "/received_events_count/" } , index: 1, event_data: AccountEvent { account: 6d7767d1f85d6d42bb18fcea71dcb89c433d98f7779c993d25205c4b7098c608, amount: 10000000 } }

有点凌乱，但是看到gas的字段，嗯，类似转账是要手续费的。

也可以阻塞的调用转账，b代表是blocking

libra% transferb 0 1 10

最后验证下转账结果

libra% query balance 0

Balance is: 100.000000

libra% query balance 1

Balance is: 62.000000